Force Displacement Transducer Research Articles

The Bronchodilator Potential of Astragalus sarcocolla: An in vitro Experiment.

To evaluate the bronchodilatory mechanism of Astragalus sarcocolla (ASE) extract on tracheal smooth muscles of rabbits. In-vitro experimental study. Place and Duration of the Study: The animal house of CMH Lahore Medical College, Lahore, and Institute of Dentistry, NUMS, from October 2022 to May 2023. Six rabbits were randomly divided into four groups. After euthanising the rabbit, the trachea was carefully dissected out and stabilised in Kreb's Henseleit solution for 30 minutes and then, stimulated by acetylcholine (Ach) 1µm, under mimicked physiological conditions. Group I served as the control group with tracheal smooth muscles stabilised with 1g tension. In Group II (positive control), tracheal smooth muscles were stimulated by potassium chloride (KCl) (80 mM and 25 mM, respectively) to get maximum tracheal smooth muscle contractions. Later, the tissue was exposed to theophylline with three molar concentrations 0.2, 0.4, 0.6, and 0.8 mM, and cumulative dose response curves were formed. In Group III (ASE group), tracheal smooth muscles were stimulated by KCl (80 mM and 25 mM) and was exposed to increasing concentration of ASE. In group IV, tissue was stimulated by KCl (25 mM) and glibenclamide (3 µM), later exposed to increasing concentration of ASE to confirm the bronchodilatory mechanism. The change in isometric contraction of the tissue was recorded using the force displacement transducer connected to a PowerLab data acquisition system. Concentration response curves were drawn, and median effective concentrations (EC50 values) and percentage inhibition were calculated. Non-linear regression was applied for the analysis of the concentration-response curves. ASE inhibited the KCl-induced low potassium (25 mM) contractions (EC50 = 0.38 mg/ml, 95% CI: 0.04 - 0.38, n = 6). It only partially inhibited the high potassium-induced contractions in tracheal smooth muscles. Pretreatment with glibenclamide showed a rightward shift of the dose-response curve. Theophylline and ASE significantly reduced the low K+ induced smooth muscle contractions in comparison to the control group (p <0.001, each). Astragalus sarcocolla extract produced bronchodilator effects through the activation of ATP sensitive potassium channels in isolated rabbit trachea. Astragalus sarcocolla, Bronchodilators, ATP-sensitive potassium channels, Effective concentration 50, Concentration response curves.

Resposta Vascular da Triiodotironina sobre Anéis de Aortas Isoladas: Contribuição de Mecanismos Redox

Abstract Background Vascular dysfunction constitutes the etiology of many diseases, such as myocardial infarction and hypertension, with the disruption of redox homeostasis playing a role in the imbalance of the vasomotor control mechanism. Our group previously has shown that thyroid hormones exert protective effects on the aortic tissue of infarcted rats by improving angiogenesis signaling. Objective Investigate the role of triiodothyronine (T3) on vascular response, exploring its effects on isolated aortas and whether there is an involvement of vascular redox mechanisms. Methods Isolated aortic rings (intact- and denuded-endothelium) precontracted with phenylephrine were incubated with T3 (10-8, 10-7, 10-6, 10-5, and 10-4 M), and tension was recorded using a force-displacement transducer coupled with an acquisition system. To assess the involvement of oxidative stress, aortic rings were preincubated with T3 and subsequently submitted to an in vitro reactive oxygen species (ROS) generation system. The level of significance adopted in the statistical analysis was 5%. Results T3 (10-4 M) promoted vasorelaxation of phenylephrine precontracted aortic rings in both intact- and denuded-endothelium conditions. Aortic rings preincubated in the presence of T3 (10-4 M) also showed decreased vasoconstriction elicited by phenylephrine (1 µM) in intact-endothelium preparations. Moreover, T3 (10-4 M) vasorelaxation effect persisted in aortic rings preincubated with NG-nitro-L-arginine methylester (L-NAME, 10 µM), a nonspecific NO synthase (NOS) inhibitor. Finally, T3 (10-4 M) exhibited, in vitro, an antioxidant role by reducing NADPH oxidase activity and increasing SOD activity in the aorta’s homogenates. Conclusion T3 exerts dependent- and independent-endothelium vasodilation effects, which may be related to its role in maintaining redox homeostasis.

Vascular Response of Triiodothyronine on Isolated Aortic Rings: Contribution of Redox Mechanisms.

Vascular dysfunction constitutes the etiology of many diseases, such as myocardial infarction and hypertension, with the disruption of redox homeostasis playing a role in the imbalance of the vasomotor control mechanism. Our group previously has shown that thyroid hormones exert protective effects on the aortic tissue of infarcted rats by improving angiogenesis signaling. Investigate the role of triiodothyronine (T3) on vascular response, exploring its effects on isolated aortas and whether there is an involvement of vascular redox mechanisms. Isolated aortic rings (intact- and denuded-endothelium) precontracted with phenylephrine were incubated with T3 (10-8, 10-7, 10-6, 10-5, and 10-4 M), and tension was recorded using a force-displacement transducer coupled with an acquisition system. To assess the involvement of oxidative stress, aortic rings were preincubated with T3 and subsequently submitted to an in vitro reactive oxygen species (ROS) generation system. The level of significance adopted in the statistical analysis was 5%. T3 (10-4 M) promoted vasorelaxation of phenylephrine precontracted aortic rings in both intact- and denuded-endothelium conditions. Aortic rings preincubated in the presence of T3 (10-4 M) also showed decreased vasoconstriction elicited by phenylephrine (1 µM) in intact-endothelium preparations. Moreover, T3 (10-4 M) vasorelaxation effect persisted in aortic rings preincubated with NG-nitro-L-arginine methylester (L-NAME, 10 µM), a nonspecific NO synthase (NOS) inhibitor. Finally, T3 (10-4 M) exhibited, in vitro, an antioxidant role by reducing NADPH oxidase activity and increasing SOD activity in the aorta's homogenates. T3 exerts dependent- and independent-endothelium vasodilation effects, which may be related to its role in maintaining redox homeostasis.

Adiponectin affects ileal contractility of mouse preparations.

Adiponectin (ADPN) has been reported to induce inhibitory effects on gastric motor activity, which, being a source of peripheral satiety signals, would contribute to the central anorexigenic effects of the hormone in rodents. However, peripheral satiety signals can also originate from the small intestine. Since there are no data on the effects of ADPN in this gut region, the present study aimed to investigate whether ADPN affects murine ileal contractility. Immunofluorescence experiments and Western blot were also performed to reveal the expression of ADPN receptors. Mechanical responses of ileal preparations were recorded in vitro via force-displacement transducers. Preparations showed a tetrodotoxin- and atropine-insensitive spontaneous contractile activity. Electrical field stimulation (EFS) induced tetrodotoxin- and atropine-sensitive contractile responses. ADPN induced a decay of the basal tension and decreased the amplitude of either the spontaneous contractility or the EFS-induced excitatory responses. All ADPN effects were abolished by the nitric oxide (NO) synthesis inhibitor NG-nitro l-arginine. The expression of the ADPN receptor, AdipoR1, but not AdipoR2, was also revealed in enteric glial cells. The present results offer the first evidence that ADPN acts on ileal preparations. The hormone exerts inhibitory effects, likely involving AdipoR1 on enteric glial cells and NO. From a physiological point of view, it could be hypothesized that the depressant action of ADPN on ileal contractility represents an additional peripheral satiety signal which, as also described for the ileal brake, could contribute to the central anorexigenic effects of the hormone.NEW & NOTEWORTHY This study provides the first evidence that adiponectin (ADPN) is able to act on ileal preparations. Functional results demonstrate that the hormone, other than causing a slight decay of the basal tension, depresses the amplitude of both spontaneous contractility and neurally induced excitatory responses of the mouse ileum through the involvement of nitric oxide. The expression of the ADPN receptor AdipoR1 and its localization on glial cells was revealed by Western blot and immunofluorescence analysis.

Pharmacological Basis for Antispasmodic, Bronchodilator, and Antidiarrheal Potential of Dryopteris ramosa (Hope) C. via In Vitro, In Vivo, and In Silico Studies.

Background:Dryopteris ramosa is used as an old treatment for several diseases. D. ramose fronds are eaten to treat gastrointestinal (GIT) issues and as an antibiotic. However, there is a dearth of literature justifying its traditional use. Aims and objectives: the current work used biological and molecular docking studies to support traditional usage and elucidate D. ramosa's multitarget mechanism. Materials and methods: Bioactive compounds were docked in silico. Force displacement transducers coupled with a power lab data gathering system examined the effects of compounds on rabbit jejunum, trachea, and aorta tissues. Albino mice and rats were used for in vivo studies. Results: Bioactive compounds interacted with inflammation, asthma, and diarrhea genes, according to in silico studies. D. ramosa crude extract (Dr.Cr) calmed impulsive contractions and K+ (80 mM)-provoked contractions in the jejunum and tracheal tissue dose-dependently, showing the presence of the Ca++ channel-blocking (CCB) effect, further verified by the rightward parallel shift of CRCs equivalent to verapamil. Polarity-based fractionation showed spasmolytic activity in Dr.DCM and muscarinic receptors mediated spasmogenic activity in the Dr.Aq fraction. Dr.Cr vasoconstricted the aortic preparation, which was totally blocked by an angiotensin II receptor antagonist. This suggests that Dr. Cr's contractile effect is mediated through angiotensin receptors. In rats and mice, it showed anti-inflammatory and antidiarrheal action. Conclusion: This study supports the traditional medicinal uses of D. ramosa against GIT disorders and may be an important therapeutic agent in the future.

Regional differences of tachykinin effects on smooth muscle and pacemaker potentials of the stomach, duodenum, ileum and colon of an emetic model, the house musk shrews

Background and aimsThe contractile effects of tachykinins on the gastrointestinal tract are well-known, but how they modulate slow-waves, particularly in species capable of emesis, remains largely unknown. We aimed to elucidate the effects of tachykinins on myoelectric and contractile activity of isolated gastrointestinal tissues of the Suncus murinus. MethodsThe effects of substance P (SP), neurokinin (NK)A, NKB and selective NK1 (CP122,721, CP99,994), NK2 (SR48,968, GR159,897) and NK3 (SB218,795, SB222,200) receptor antagonists on isolated stomach, duodenum, ileum and colon segments were studied. Mechanical contractile activity was recorded using isometric force displacement transducers. Electrical pacemaker activity was recorded using a microelectrode array. ResultsCompared with NKA, SP induced larger contractions in stomach tissue and smaller contractions in intestinal segments, where oscillation magnitudes increased in intestinal segments, but not the stomach. CP122,721 and GR159,897 inhibited electrical field stimulation-induced contractions of the stomach, ileum and colon. NKB and NK3 had minor effects on contractile activity. The inhibitory potencies of SP and NKA on the peristaltic frequency of the colon and ileum, respectively, were correlated with those on electrical pacemaker frequency. SP, NKA and NKB inhibited pacemaker activity of the duodenum and ileum, but increased that of the stomach and colon. SP elicited a dose-dependent contradictive pacemaker frequency response in the colon. ConclusionThis study revealed distinct effects of tachykinins on the mechanical and electrical properties of the stomach and colon vs. the proximal intestine, providing a unique aspect on neuromuscular correlation in terms of the effects of tachykinin on peristaltic and pacemaker activity in gastrointestinal-related symptoms.

The Role of Perivascular Adipose Tissue in Early Changes in Arterial Function during High-Fat Diet and Its Combination with High-Fructose Intake in Rats

The aim of the current study was to evaluate the influence of a high-fat diet and its combination with high-fructose intake on young normotensive rats, with focus on the modulatory effect of perivascular adipose tissue (PVAT) on the reactivity of isolated arteries. Six-week-old Wistar–Kyoto rats were treated for 8 weeks with a control diet (10% fat), a high-fat diet (HFD; 45% fat), or a combination of the HFD with a 10% solution of fructose. Contractile and relaxant responses of isolated rat arteries, with preserved and removed PVAT for selected vasoactive stimuli, were recorded isometrically by a force displacement transducer. The results demonstrated that, in young rats, eight weeks of the HFD might lead to body fat accumulation and early excitation of the cardiovascular sympathetic nervous system, as shown by increased heart rate and enhanced arterial contractile responses induced by endogenous noradrenaline released from perivascular sympathetic nerves. The addition of high-fructose intake deteriorated this state by impairment of arterial relaxation and resulted in mild elevation of systolic blood pressure; however, the increase in arterial neurogenic contractions was not detected. The diet-induced alterations in isolated arteries were observed only in the presence of PVAT, indicating that this structure is important in initiation of early vascular changes during the development of metabolic syndrome.

An Analytical Model for the Stiffness of Slotted Disk Springs

The slotted disk spring is an important part of ultrasonic motors. Its mechanical properties directly affect the running stability of the motor. In this study, an analytical model is developed to solve the preload problem for slotted disk springs used in ultrasonic motors. The outer conical ring of the slotted disk spring is modeled using the conical shell theory. The inner separated teeth are modeled by the cantilever beam theory. An analytical mechanical model for the force-displacement relationship of the entire slotted disk spring is then developed. The results of the experiment based on a force-displacement transducer and the results from the analytical model, a finite element calculation, and the Schremmer formula are compared to validate the analytical model. The results show that the proposed model has the highest accuracy. Parameter-sensitivity analysis for the slotted disk spring is finally performed, and a new slotted disk spring with a long zero-stiffness interval is designed for a 40[Formula: see text]mm traveling wave rotary ultrasonic motor.

The Inhibitory Effect of Extra Virgin Olive Oil and Its Active Compound Oleocanthal on Prostaglandin-Induced Uterine Hypercontraction and Pain—Ex Vivo and In Vivo Study

Primary dysmenorrhea is a common occurrence in adolescent women and is a type of chronic inflammation. Dysmenorrhea is due to an increase in oxidative stress, which increases cyclooxygenase-2 (COX-2) expression, increases the concentration of prostaglandin F2α (PGF2α), and increases the calcium concentration in uterine smooth muscle, causing excessive uterine contractions and pain. The polyphenolic compound oleocanthal (OC) in extra virgin olive oil (EVOO) has been shown to have an anti-inflammatory and antioxidant effect. This study aimed to investigate the inhibitory effect of extra virgin olive oil and its active ingredient oleocanthal (OC) on prostaglandin-induced uterine hyper-contraction, its antioxidant ability, and related mechanisms. We used force-displacement transducers to calculate uterine contraction in an ex vivo study. To analyze the analgesic effect, in an in vivo study, we used an acetic acid/oxytocin-induced mice writhing model and determined uterus contraction-related signaling protein expression. The active compound OC inhibited calcium/PGF2α-induced uterine hyper-contraction. In the acetic acid and oxytocin-induced mice writhing model, the intervention of the EVOO acetonitrile layer extraction inhibited pain by inhibiting oxidative stress and the phosphorylation of the protein kinase C (PKC)/extracellular signal-regulated kinases (ERK)/ myosin light chain (MLC) signaling pathway. These findings supported the idea that EVOO and its active ingredient, OC, can effectively decrease oxidative stress and PGF2α-induced uterine hyper-contraction, representing a further treatment for dysmenorrhea.

Nitric oxide pathway-mediated relaxant effect of PPAR (Peracisome proliferator activated receptor)-Gamma agonist in the guinea-pig isolated trachea.

Objectives: This study focuses on the role of the mediator of smooth muscles i.e. nitric oxide in the effect of rosiglitazone on the relaxation of contractions in guinea pig trachea induced by histamine. Study Design: Experimental Study. Setting: Department of Pharmacology, Army Medical College, Rawalpindi. Period: 1st December 2018 till 14th December 2018. Material &amp; Methods: The activity of the trachealis mucle of the guinea pigs was noted by the use of oxygenated solution of Krebs-Henseleit. The contractions were noted with rosiglitazone alone as well as in presence of an ester of L-nitro-arginine-methyl, which can antagonize the activity of NO. The activity was measured by the use of an isometric force displacement transducer and was then recorded on an oscillograph with four channels. Results: The ester L-nitro-arginine-methyl was able to reduce the relaxant effect of rosiglitazone on the contractions induced by histamine. Conclusion: It can be suggested that the relaxation induced by rosiglitazone is mediated in part through NO.

Vaso‐relaxant Effect of Zingiber officinale Extract Involves Release of Nitric Oxide from the Endothelium

IntroductionZingiber officinale (ZO) is an important plant with several medicinal, nutritional and ethnomedical values. The blood pressure lowering effect of ZO has been reported in experimental animals and human and some mechanisms have been postulated, including; blockage of voltage dependent calcium channel, stimulation of muscarinic receptors and serotonergic antagonistic property. The aim of this study is to investigate the vaso‐relaxant effect of the extract of ZO and the mechanism by which it is produced.MethodRhizomes of ZO were extracted in 80% methanol. Thoracic aorta isolated from male rabbits were cut into rings of 3–5 mm, mounted in organ baths containing 25 ml Krebs physiological solution maintained at 37 °C and bubbled continuously with a mixture of 95% O2 and 5% CO2. The aortic rings were equilibrated for 30 min at a resting tension of 1 g. Responses were recorded isometrically via a force displacement transducer connected to a recording system. The presence of functional endothelium was checked by the ability of acetylcholine (1μM) to induce relaxation on phenylepherine (PE, 1μM) contracted rings. The relaxant responses to ZO was recorded by adding cumulative concentrations (10, 20, 40, 80, 100, 500, 1000 μg/ml) of ZO. To investigate the involvement of endothelium in the vaso‐relaxant action, endothelium was removed by gently rubbing the luminal surface of the ring with a polyethylene tube. To investigate which endothelium‐derived vasorelaxant factors were involved, the rings were pre‐incubated with Nitro‐L‐arginine methyl ester (L‐NAME, 10 μM) or indomethacin (10 μM) for 30 min before addition of the spasmogen and ZO. Relaxant responses were expressed as percentage relaxation from PE‐precontraction levels. The EC50 (the concentration required to cause half‐maximal relaxation) was calculated from the concentration‐response curve. Results were expressed as means ± s.e.m. Student t‐test was used to assess the significant differences at (p &lt; 0.05)ResultsZO produced a vaso‐relaxation effect on rings pre‐contracted with PE (1μM) at concentrations of 20–100 μg/ml in endothelium intact rings with an EC50 of 14.8±1.2 μg/ml (Figure 1). This relaxation was not however seen at 500–1000 μg/ml but rather a vaso‐contraction was observed. In endothelium denuded rings, the vaso‐relaxation effect of ZO at 20–100 μg/ml was abolished while vaso‐relaxation was observed with 500–1000 μg/ml, the concentrations that otherwise produced contraction in endothelium intact aortic rings. Pre‐incubation of the tissues with L‐NAME (10μM) abolished the relaxant effect of ZO at 20–100μg/ml but caused relaxation effect with 500–1000 μg/ml similar to that observed with endothelium denuded rings. Pretreatment with indomethacin abolished the relaxant effect of ZO at 20μg/ml but not at 40 μg/ml and above (Figure 2).ConclusionVaso‐relaxant effect of ZO is seen at lower concentrations, endothelium dependent and may involve the release of nitric oxide from the endothelium. There may be interplay between contractile and relaxant compounds in crude extract of ZO at concentrations above 500 μg/ml.Support or Funding InformationThe PhD study grant awarded to I.M Adebisi by Usmanu Danfodiyo University, Sokoto, Nigeria is acknowledgedRelaxation effect of methanol extract of Zingiber officinale (ZO) on phenylephrine‐precontracted aortic rings with intact endothelium. Data represent the mean ± s.e.m. of four individual experiments. * is p&lt;0.05Figure 1Relaxation effect of methanol extract of Zingiber officinale (ZO) on phenylephrine‐precontracted aortic rings with endothelium, without endothelium and effect of L‐NAME (10 μM), and Indomethacin (10 μM) on ZO induced vasorelaxation on phenylephrine‐precontracted aortic rings with endothelium. Data represent the mean ± s.e.m. of four individual experiments. * is p&lt;0.05Figure 2

Daily Meal Supplemented with Astaxanthin-Enriched Yolk Has Mitigative Effects against Hypertension in Spontaneously Hypertensive Rats.

The aim of this study was to investigate the effects of egg yolk powder enriched with astaxanthin (ASX-E) on blood pressure in spontaneously hypertensive rats (SHR) and to verify the benefits of ASX-E as a functional food. To investigate the antihypertensive effect, SHR were fed with an ASX-E mixed diet before hypertension development. Blood pressures were determined periodically during the study by the tail-cuff method. At the end of the study, animals were euthanized, and their thoracic aortas were collected to determine vascular conductance. The thoracic aorta tension was measured with a force displacement transducer. Concentration-dependent response relationships were determined by cumulative addition of 10-9-10-4 M Carbamoylcholine (Cch). Blood pressures of the SHR in the ASX-E mixed diet group were ASX-dose-dependently lower than that of those in the control group. In SHR fed with an ASX-E mixed diet, Cch induced vasorelaxation in the thoracic aorta with endothelium lining but not without endothelium. However, the antihypertensive effect of ASX-E was not observed on blood pressures in SHR that were fed with ASX-E only after the development of hypertension. Results suggest that ASX-E protects endothelial function and thereby prevents the development of hypertension. Hence, the results of our research indicate that daily consumption of ASX-E has a potential benefit on human health.

Mechanism of Spasmogenic Activity Stimulated by Aqueous Ethanolic Leaf Extract of Mucuna pruriens on Isolated Uterine Muscle of Albino Rats

Aims: To investigate the effect of aqueous ethanolic leaf extract of this medicinal plant on isolated uterine smooth muscle strips of the rat and to determine its mechanism of action.&#x0D; Study Design: Laboratory-experimental design was used in this study.&#x0D; Place and Duration of Study: The study was carried out in the Department of Veterinary Physiology and Biochemistry of Michael Okpara University of Agriculture, Umudike, Nigeria, Department of Pharmacology and Toxicology of the Faculty of Pharmacy, University of Nigeria, Nsukka, and the Department of Veterinary Physiology and Pharmacology, University of Nigeria, Nsukka, Nigeria between June and October 2014.&#x0D; Methodology: Fresh leaves of Mucuna pruriens were identified and collected by a taxonomist from Nsukka, Nigeria. The leaves were then air dried and pulverized into powder. This was then subjected to cold extraction using petroleum ether (70-90) and 70% aqueous ethanol, after which the extract was left to dry at room temperature. Estrogenised uterine strips (12mm) were harvested from non-pregnant, sexually matured albino rats (180 g -250 g) and suspended in a 35ml organ bath containing Krebs’ physiological salt solution. The organ bath was connected to an isometric electronic force displacement transducer and a physiograph. Drugs such as Salbutamol, Isoprenaline, Adrenaline, Propranolol, Atipamezole and Prazosin were used as either agonists or antagonists to determine the mechanism of action of the extract. Atropine sulphate and Cyproheptadine were also used as test drugs. Concentrations of these drugs presented in the body of this work represent the final nutrient bath concentrations.&#x0D; Results: M. pruriens caused a dose -dependent increase in uterine muscle contraction with an EC50 of 0.88 mg/ml, n=4. The contraction was unaffected by atropine sulphate (0.042 µmol), but abolished by salbutamol (0.012-0.4 µmol), isoprenaline (0.06-0.23 µmol), and adrenaline (16 nmol). The uterine muscle contractions were enhanced by propranolol (1 µmol) in a dose- dependent manner. Prazosin (0.069-0.14 µmol) and atipamezole (3.3-13.7 nmol) were unable to abolish contractions stimulated by the extract. However, 0.2 µmol of cyproheptadine caused 80% suppression of the extract –induced uterine contraction&#x0D; Conclusion: It is concluded that aqueous ethanolic leaf extract of M. pruriens, has ability to cause uterine smooth muscle contraction hence, justifies its reported use traditionally as a uterine stimulant. This contraction is most likely exerted via the 5-HT receptor activation (activated by low concentrations of serotonin).

Voluntary biting behavior as a functional measure of orofacial pain in mice

IntroductionPain-related behavior secondary to masticatory function can be assessed with the rodent bite force model. A reduction of the bite force has been shown to be related to pain associated with the masseter muscle and jaw activity, while an increase in bite force suggests improvement of muscle function and less pain. To evaluate the usefulness of the bite force measure in studying long-lasting orofacial pain we analyzed biting parameters during prolonged myofascial pain induced by ligation injury of the masseter muscle tendon (TL) in mice. MethodsC57Bl/6 mice were habituated to bite at a pair of aluminum plates attached to a force displacement transducer. The transduced voltage signals were amplified and converted to force through calibration with a standard weight set. Voluntary biting behavior was recorded for 100 s/session and those with bite forces ≥980 mN were analyzed. Nociception was also verified with von Frey, conditioned place avoidance (CPA) tests and mouse grimace scale. Persistent orofacial pain was induced with unilateral ligation of one tendon of the masseter muscle (TL). ResultsTo reduce interference of random bites of smaller forces, the top 5 or 15 bite forces (BF5/15) were chosen as a measure of masticatory function and related to pain behavior. Both male and female mice exhibited similar BF5/15. For the first nascent test of all mice, mean bite force was significantly and positively correlated with the body weight. However, this correlation was less clear in the latter tests (2–8 w). TL induced a reduction of BF5/15 that peaked at 1 w and returned to the baseline within 3 w. The von Frey and CPA tests indicated that mechanical allodynia/hyperalgesia persisted at the time when the BF had returned to the pre-injury level. Infusion of pain-relieving bone marrow stromal cells improved biting behavior in both male and female mice as shown by significantly increased BF5/15, compared to vehicle-treated mice. ConclusionsMouse voluntary biting behavior can be reliably measured and quantified with a simplified setup. The bite force showed an inverse relationship with the level of pain after TL and was improved by pain-relieving manipulations. However, the injury-induced reduction of bite force peaked early and did not parallel with other measures of nociception in the later phase of hyperalgesia. The results suggest that multiple factors such as the level of habituation, cognitive motive, physical status, and feeding drive may affect random voluntary biting and confound the biting parameters related to maintained hyperalgesia.

Effects of gentamicin on spontaneous and agonist-induced in vitro contractions of isolated myometrial tissue from pregnant cows

The aim of the present study is to examine the effects of gentamicin sulphate on spontaneous, oxytocin and PGF&lt;sub&gt;2α&lt;/sub&gt; induced in vitro contractions of myometrium isolated from pregnant cows. Myometrial strips were obtained from healthy pregnant cows and suspended in a covered organ bath filled with Krebs’ solution at 37°C (pH 7.4) continuously bubbled with 95% oxygen and 5% carbon dioxide: isometric contractions were recorded using an isometric force displacement transducer. After the stabilization of spontaneous contractile activity during a 90-minute equilibration period, contractions were recorded for 20 minutes (control). Gentamicin sulphate was then added to the tissue bath cumulatively and the responses were recorded every 20-minutes for each consecutive dose of gentamicin. In agonist-induced contractions, oxytocin or PGF&lt;sub&gt;2α&lt;/sub&gt; was added to the tissue bath at the end of the equilibration period and the same protocol was followed to investigate the effects gentamicin on these agonist-induced contractions. Gentamicin decreased the frequency and inhibited the amplitude of the spontaneous contractions in a dose dependent manner (p &amp;lt; 0.05). The mean frequency and amplitude of oxytocin-induced contractions was significantly inhibited by the application of gentamicin (p &amp;lt; 0.05). Gentamicin also inhibited the contractions induced by PGF&lt;sub&gt;2α&lt;/sub&gt; in a dose dependent manner (p &amp;lt; 0.05). This study showed gentamicin inhibited, depending on the dosage, oxytocin and PGF&lt;sub&gt;2α&lt;/sub&gt; induced contractions of myometrium isolated from pregnant cows. Upon clinically examining the findings obtained by the study, gentamicin can be used as an antibacterial in septic abort and chorioamniotis in order to prevent premature birth, abortion and early uterus contractions. Further studies are necessary to test whether the same effect will take place in vivo and to examine the effects of longterm use of gentamicin on offsprings.

Adiponectin affects the mechanical responses in strips from the mouse gastric fundus.

AIMTo investigate whether the adipocytes derived hormone adiponectin (ADPN) affects the mechanical responses in strips from the mouse gastric fundus.METHODSFor functional experiments, gastric strips from the fundal region were cut in the direction of the longitudinal muscle layer and placed in organ baths containing Krebs-Henseleit solution. Mechanical responses were recorded via force-displacement transducers, which were coupled to a polygraph for continuous recording of isometric tension. Electrical field stimulation (EFS) was applied via two platinum wire rings through which the preparation was threaded. The effects of ADPN were investigated on the neurally-induced contractile and relaxant responses elicited by EFS. The expression of ADPN receptors, Adipo-R1 and Adipo-R2, was also evaluated by touchdown-PCR analysis.RESULTSIn the functional experiments, EFS (4-16 Hz) elicited tetrodotoxin (TTX)-sensitive contractile responses. Addition of ADPN to the bath medium caused a reduction in amplitude of the neurally-induced contractile responses (P < 0.05). The effects of ADPN were no longer observed in the presence of the nitric oxide (NO) synthesis inhibitor L-NG-nitro arginine (L-NNA) (P > 0.05). The direct smooth muscle response to methacholine was not influenced by ADPN (P > 0.05). In carbachol precontracted strips and in the presence of guanethidine, EFS induced relaxant responses. Addition of ADPN to the bath medium, other than causing a slight and progressive decay of the basal tension, increased the amplitude of the neurally-induced relaxant responses (P < 0.05). Touchdown-PCR analysis revealed the expression of both Adipo-R1 and Adipo-R2 in the gastric fundus.CONCLUSIONThe results indicate for the first time that ADPN is able to influence the mechanical responses in strips from the mouse gastric fundus.

Vasorelaxant effect of sinensetin via the NO/sGC/cGMP pathway and potassium and calcium channels.

Orthosiphon stamineus Benth. (Lambiaceae) is an important traditional plant for the treatment of hypertension. Previous studies have demonstrated that the sinensetin content in O. stamineus is correlated with its vasorelaxant activity. However, there is still very little information regarding the vasorelaxant effect of sinensetin due to a lack of scientific studies. Therefore, the present study was designed to investigate the underlying mechanism of action of sinensetin in vasorelaxation using an in vitro precontraction aortic ring assay. The changes in the tension of the aortic ring preparations were recorded using a force-displacement transducer and the PowerLab system. The mechanisms of the vasorelaxant effect of sinensetin were determined in the presence of antagonists. Sinensetin caused relaxation of the aortic ring precontracted with PE in the presence and absence of the endothelium and with potassium chloride in endothelium-intact aortic rings. In the presence of Nω-nitro-L-arginine methyl ester (nitric oxide synthase inhibitor), methylene blue (cyclic guanosine monophosphate lowering agent), ODQ (selective soluble guanylate cyclase inhibitor), indomethacin (a nonselective cyclooxygenase inhibitor), tetraethylammonium (nonselective calcium activator K+ channel blocker), 4-aminopyridine (voltage-dependent K+ channel blocker), barium chloride (inwardly rectifying Kir channel blocker), glibenclamide (nonspecific ATP-sensitive K+ channel blocker), atropine (muscarinic receptor blocker), or propranolol (β-adrenergic receptor blocker), the relaxation stimulated by sinensetin was significantly reduced. Sinensetin was also active in reducing Ca2+ release from the sarcoplasmic reticulum (via IP3R) and in blocking calcium channels (VOCC). The present study demonstrates the vasorelaxant effect of sinensetin, which involves the NO/sGC/cGMP and indomethacin pathways, calcium and potassium channels, and muscarinic and beta-adrenergic receptors.

Relaxation of Porcine Isolated Irides by Novel Hydrogen Sulfide‐Releasing Compounds

PurposeWe have previously reported that hydrogen sulfide (H2S)‐releasing compounds can elicit relaxation of pre‐contracted ocular vascular and non‐vascular smooth muscles. In the present study, we compared the pharmacological actions of novel mitochondrial‐targeting H2S‐releasing compounds (AP39, AP123, and RT‐01) with those of ADT‐OH on pre‐contracted porcine isolated irides.MethodsIsolated porcine iris muscle strips were set up in organ baths containing oxygenated Krebs buffer solution maintained at 37° C and gassed with 95% O2 and 5% CO2. The muscle strips were set to an initial resting tension of 0.15 g and longitudinal isometric tension was recorded via a grass FT03 Force‐Displacement Transducers and analyzed using the PolyView computer software. Pharmacological actions of AP39, AP123 and RT‐01 were assessed in the presence of tone induced by submaximal concentrations of the muscarinic agonist, carbachol. The cyclo‐oxygenase inhibitor, flurbiprofen (10 μM) was added to Krebs buffer solution during the incubation period and was present for duration of the experiments. ADT‐OH was used as a positive control in experiments using AP39, AP123 and RT‐01 since it lacked the mitochondrial targeting moiety.ResultsAP39 (1 nM – 10 μM), RT‐01 (1 nM – 10 μM) and AP123 (1 nM – 10 μM) elicited concentration‐dependent relaxations of carbachol‐induced tone. The rank order of activity was as follows (IC50): AP39, 50 nM (n = 10); RT‐01, 100 nM (n = 4); and AP123, 300 nM (n = 4). Likewise, the non‐mitochondrial‐targeting H2S donor, ADT‐OH (1 nM – 10 μM) caused a concentration‐dependent relaxation of porcine irides with an IC50 of 50 nM (n = 8).ConclusionsWe conclude that both novel mitochondria‐targeting H2S‐releasing compounds and their control counterpart, ADT‐OH can elicit relaxation of isolated porcine irides. The mitochondrial storage sites of this gas may not be involved in the inhibitory response caused by H2S‐releasing compounds in the porcine iris smooth muscle.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A microelectromechanical systems (MEMS) force-displacement transducer for sub-5 nm nanoindentation and adhesion measurements.

We present a highly sensitive force-displacement transducer capable of performing ultra-shallow nanoindentation and adhesion measurements. The transducer utilizes electrostatic actuation and capacitive sensing combined with microelectromechanical fabrication technologies. Air indentation experiments report a root-mean-square (RMS) force resolution of 1.8 nN and an RMS displacement resolution of 0.019 nm. Nanoindentation experiments on a standard fused quartz sample report a practical RMS force resolution of 5 nN and an RMS displacement resolution of 0.05 nm at sub-10 nm indentation depths, indicating that the system has a very low system noise for indentation experiments. The high sensitivity and low noise enables the transducer to obtain high-resolution nanoindentation data at sub-5 nm contact depths. The sensitive force transducer is used to successfully perform nanoindentation measurements on a 14 nm thin film. Adhesion measurements were also performed, clearly capturing the pull-on and pull-off forces during approach and separation of two contacting surfaces.

Relaxin influences ileal muscular activity through a dual signaling pathway in mice.

AIMTo investigate the signaling pathways involved in the relaxin (RLX) effects on ileal preparations from mice through mechanical and electrophysiological experiments.METHODSFor mechanical experiments, ileal preparations from female mice were mounted in organ baths containing Krebs-Henseleit solution. The mechanical activity was recorded via force-displacement transducers, which were coupled to a polygraph for continuous recording of isometric tension. Electrophysiological measurements were performed in current- and voltage-clamp conditions by a microelectrode inserted in a single smooth muscle cell (SMC) of the ileal longitudinal layer. Both the membrane passive properties and inward voltage-dependent L-type Ca2+ currents were recorded using suitable solutions and voltage stimulation protocols.RESULTSMechanical experiments showed that RLX induced a decay of the basal tension and a reduction in amplitude of the spontaneous contractions. The effects of RLX were partially reduced by 1H-[1,2,4]oxadiazolo[4,3-a]-quinoxalin-1-one (ODQ) or 9-cyclopentyladenine mesylate (9CPA), inhibitors of guanylate cyclase (GC) and adenylate cyclase (AC), respectively, and were abolished in the concomitant presence of both drugs. Electrophysiological experiments demonstrated that RLX directly influenced the biophysical properties of ileal SMCs, decreasing the membrane conductance, hyperpolarizing the resting membrane potential, reducing the L-type calcium current amplitude and affecting its kinetics. The voltage dependence of the current activation and inactivation time constant was significantly speeded by RLX. Each electrophysiological effect of RLX was reduced by ODQ or 9CPA, and abolished in the concomitant presence of both drugs as observed in mechanical experiments.CONCLUSIONOur new findings demonstrate that RLX influences ileal muscle through a dual mechanism involving both GC and AC.