Reduced Muscle Contraction Research Articles

Trendelenburg gait after total hip arthroplasty due to reduced muscle contraction of the hip abductors and extensors

BackgroundDespite experiencing pain relief and improved activities of daily living after total hip arthroplasty (THA) for osteoarthritis of the hip, a Trendelenburg gait may be observed in some patients. The concentric and eccentric contraction patterns of hip muscles in a Trendelenburg gait are not well understood. MethodsThis study included 89 patients (28 males and 61 females, mean age 66.5 ± 8.4 years, mean postoperative period 1.3 ± 0.4 years) after unilateral THA without functional impairment on the contralateral side. Gait analysis utilized a three-dimensional motion capture system to assess pelvis and hip angles, hip moment, and hip power. A Trendelenburg gait was defined as positive when nonoperative pelvic descent occurred at 30 % of the gait cycle, equivalent to mid-stance. Patients were classified into Trendelenburg gait-positive and -negative groups for statistical analysis. Unpaired t-test and chi-square test were used to compare the two groups. Multiple regression analysis was conducted to identify factors associated with the presence of a Trendelenburg gait. ResultsA Trendelenburg gait was observed in 24 patients (27 %). Multiple regression analysis indicated that abduction (p < 0.01) and extension (p = 0.03) of hip joint power were significant determining of a Trendelenburg gait. Patients with a Trendelenburg gait exhibited reduced eccentric contraction of the hip abductor muscles and decreased concentric contraction of hip extensor muscles during early to mid-stance of their gait. ConclusionCentrifugal contraction of hip abductor muscles and diminished eccentric contractility of hip extensor muscles appear crucial for hip stabilization mechanisms during gait after THA.

Effects of 4-week circuit strength combined with blood flow restriction training on muscle status and performance in Taekwondo athletes

This study explored the effects of a 4-week circuit strength training with blood flow restriction on Taekwondo athletes. Six male athletes (age 20.6 ± 1.85, height 184.3 ± 7.63 cm, training duration 7.5 ± 2.07 years) were assessed for explosive strength, muscle recruitment, and sport-specific skills. The regimen encompassed evaluations of lower limb power, Isokinetic strength, force via electronic kicks, and Tensiomyography (TMG) measurements pre-and post-training. Outcomes revealed enhanced jumping abilities, improved knee muscles, and superior kicking skills. There was a notable increase in muscle fibre recruitment and a shift towards type II muscle fibres. Medial thigh muscle displacement showed a positive correlation with jump duration, while lateral thigh muscles indicated a connection with kick numbers. The regimen notably improved explosive power, muscle fibre distribution, and reduced muscle contraction times. Yet, no significant changes in lower limb bilateral symmetry or the link between TMG parameters and athletic prowess were observed.

Muscle contractions and pain sensation accompanying high-frequency electroporation pulses

To minimize neuromuscular electrical stimulation during electroporation-based treatments, the replacement of long monophasic pulses with bursts of biphasic high-frequency pulses in the range of microseconds was suggested in order to reduce muscle contraction and pain sensation due to pulse application. This treatment modality appeared under the term high-frequency electroporation (HF-EP), which can be potentially used for some clinical applications of electroporation such as electrochemotherapy, gene electrotransfer, and tissue ablation. In cardiac tissue ablation, which utilizes irreversible electroporation, the treatment is being established as Pulsed Field Ablation. While the reduction of muscle contractions was confirmed in multiple in vivo studies, the reduction of pain sensation in humans was not confirmed yet, nor was the relationship between muscle contraction and pain sensation investigated. This is the first study in humans examining pain sensation using biphasic high-frequency electroporation pulses. Twenty-five healthy individuals were subjected to electrical stimulation of the tibialis anterior muscle with biphasic high-frequency pulses in the range of few microseconds and both, symmetric and asymmetric interphase and interpulse delays. Our results confirm that biphasic high-frequency pulses with a pulse width of 1 or 2 µs reduce muscle contraction and pain sensation as opposed to currently used longer monophasic pulses. In addition, interphase and interpulse delays play a significant role in reducing the muscle contraction and/or pain sensation. The study shows that the range of the optimal pulse parameters may be increased depending on the prerequisites of the therapy. However, further evaluation of the biphasic pulse protocols presented herein is necessary to confirm the efficiency of the newly proposed HF-EP.

Evaluation of the effect of levator ani muscle contraction on post-prostatectomy urinary incontinence using cine MRI.

Post-prostatectomy urinary incontinence (PPI) is the greatest concern for urologists after radical prostatectomy (RP). It is thought that PPI is composed of multiple factors including static and dynamic components. The purpose of this study is to show visually levator ani muscle (LAM) contraction during pelvic floor muscle contraction and to evaluate the dynamic differences in its contraction between men with and without PPI. This study was a case-control study of the urinary continent or incontinent men. It investigated whether LAM contraction was involved in urinary leakage based on examination of LAM contraction by cine magnetic resonance imaging. The LAM contracted from the coccyx to the pubis in the same manner before and after surgery. The degree of contraction of the LAM in post-prostatectomy groups was smaller than that in the healthy adult group. The contraction distances of each part of the pelvic floor were decreased by 50%-70% in the incontinence group compared to those in the continence group. The bladder neck moved 2.5-fold further in the continence group and the direction of movement was more vertical than in the incontinence group. Urethral compression was attenuated by about 40% in the incontinence group compared to that in the continence group. RP can cause damage to the LAM. LAM contraction is reduced after RP compared with that in healthy adult men. In men with PPI, the reduced muscle contraction might not compress the urethra sufficiently when abdominal pressure is raised. Pelvic floor muscle training might provide a meaningful method for the recovery of LAM contraction in patients with PPI.

Study on Optimal Parameter and Target for Pulsed-Field Ablation of Atrial Fibrillation.

Pulsed-field ablation (PFA) had potential advantages in atrial fibrillation ablation, and we aim to confirm the optimal parameter and target of PFA for atrial fibrillation. Two ablation modes in vitro of single-cell system (ablation in electrode cup) and monolayer cell system (ablation in inserts with electrode tips) were established to perform PFA for myocardial cell H9C2 and smooth muscle cell A7r5. Ablation effect, calcium ion influx, the expression of Cx45, and surface morphological change were observed. Three Bama minipigs were used to verify the in vivo ablation effect of PFA. In monolayer cell system, H9C2 was significantly sensitive to PFA compared with A7r5, with shrinking of the whole monolayer. The ablation effect of bidirectional pulse was weaker than that of the two mono-polar pulses. Expressed Cx45 proteins were increased in H9C2 but decreased in A7r5 cells. Bidirectional PFA performed on Bama minipigs was able to effectively block electrical activity from the pulmonary vein to the atrium with week muscle contraction, not generating pulmonary vein stenosis. Bidirectional PFA was able to significantly ablate myocardial cells, maintain cell–cell connection, and reduce muscle contraction, which was a kind of optimized PFA strategy for atrial fibrillation.

Abstract No. 523 Pre-operative Botox injection for ventral hernia repair: early experience at a single institution

Ventral wall hernias are a common pathology occurring in 10% of open abdominal operations. Surgical management of hernias can be complex due to chronic muscle contraction resulting in recurrence and significant morbidity. Botulism Toxin A (BTA) has been described as a preoperative therapy utilized to reduce muscle contraction and increase intrabdominal volume. Interventional radiologists may increase procedural accuracy while reducing complications by utilizing ultrasound (US) guidance; however, corresponding literature and data are sparse. The present study describes the efficacy and safety of pre-operative US-guided BTA injection in patients undergoing ventral abdominal wall hernia repair at a single institution. Eight patients underwent BTA injection from 2018 to 2020. Injections were performed via ultrasound guidance targeting the external oblique, internal oblique, and transversus abdominis muscles at three locations along the right and left lateral abdominal wall. Retrospective chart review was performed documenting date of birth, sex, preoperative hernia size by computed tomography (CT) evaluation, postoperative hernia size by CT evaluation, post-operative clinical assessment of hernia repair, number of injections, units of Botox, complications, use of mesh, date of repair, and technical success. Technical success was considered to be the ability to inject the BTA in the target muscles. The cohort consisted of 25% (2/8) women and 75% (6/8) men with an average age of 43.3 ± 8.1 years. The maximal pretreatment diameter of the hernia defect prior to surgery was 14.7 ± 4.6 cm. The technical success was 100% (8/8). The patients each had a total of 18 injections and 7/8 (87.5%) had 300 units of BTA while 1/8 (12.5%) had 240 units of BTA injected. None of the patients suffered complications from the injections. The patients underwent hernia repair at an average of 34.7 ± 4 days following BTA injection. Twenty percent (1/5) of patients did not require mesh insertion. Pre-operative US-guided BTA injection is a safe procedure that can aid in ventral abdominal hernia repair via induction of flaccid paralysis.

Evaluation of holding handheld scanner on muscle activity, heart rate variability, and model accuracy in industrial applications

PurposeThe capabilities of handheld scanners have been investigated previously in different applications, without considering its impact on the accuracy of model, heart rate variability (HRV), subjective measurements, and worker muscular activity. The present study aims to evaluate the impact of using two handheld scanners, elevation, and orientation of object that is scanned on the basis of aforementioned parameters. Design/methodology/approachTo achieve these objectives, electromyographic measurements of six muscles were obtained. Moreover, dependent variables include; NASA task load index (NASA-TLX) as a subjective measure, HRV, and accuracy of the model; while, the scanner-type (laser versus white light scanner), target orientation (0° versus 45°), and elevation (50 cm versus 80 cm table height) were the independent variables. FindingsThe results of the within-subject design indicated that a light scanner exhibited less accurate performance, lower cardiac cost, less subjective NASA-TLX, and less task execution time than the laser scanner. Originality/valueWhen using the laser scanner, to reduce muscle contraction and decrease the subjective NASA-TLX, the target elevation and orientation angle with respect to the horizontal plane must be 80 cm and 45°, respectively. However, when using the light scanner, to reduce muscle contraction and the subjective NASA-TLX, the target elevation and orientation angle with respect to the horizontal plane must be 50 cm and 0°, respectively. Furthermore, cardiac rhythms were less stressed when using the laser scanner at a 50 cm target elevation and light scanner at an 80 cm target elevation.

The Difference Incidence of Maternal Uterine Inertia Between Labor With and Without Anemia in Hospital of dr. Soebandi Jember

One of the indirect causes of maternal death is anemia. Anemia in pregnancy is a woman with a hemoglobin level below 11 g / dl caused by iron deficiency in pregnant women so that the hemoglobin level becomes low and cannot meet the need for oxygen to perfusion to the tissues. This consumes energy in the affected muscles and buildup of lactic acid which causes fatigue and reduced muscle contraction during labor. Inadequate uterine contractions are called uterine inertia and are characterized by a prolonged phase of labor, which is weak, rarely and short duration. The purpose of this study was to determine the differences in the incidence of uterine inertia between labor and anemia released in RSD dr. Soebandi Jember. This study was analytic observational with a cross sectional research design. The study population was all pregnant women who had improved labor and were included in the medical record at RSD Dr. Soebandi Jember period January 1, 2017 - December 31, 2017. Samples from this study were mothers who had approved the delivery and fulfilled the inclusion and exclusion criteria that had been determined until the number of samples could be fulfilled. The number of samples in this study were 76 samples. The type of data used in this study is secondary data obtained by researchers from the medical records of pregnant women who have received labor. The data included in this study contain demographic data consisting of the age of pregnant women and parity, clinical data in the form of uterine inertia and laboratory data consisting of anemia status. In analyzing the data with Chi Square test (X²), a significance value of 0.011 was obtained so that it can be concluded that Ho is rejected and Ha is accepted which means that the incidence of uterine inertia between free labor and anemia is not important in RSD Dr. Soebandi Jember.&#x0D; Keywords: anemia, uterine inertia, pregnancy, age, parity.&#x0D;

Running ground reaction force complexity at the initial stance phase increased with ageing

ABSTRACT Running mechanics could be influenced by some degenerative musculoskeletal changes associated with ageing. However, the shoe effect on ground reaction force (GRF) amplitude and complexity of older runners is still unclear. The objective of our study was to assess the effects of age and shoe on amplitude and complexity of GRF during treadmill running. In total, 20 healthy runners were recruited. GRF data were collected for 13 younger runners and seven older runners during running on an instrumented treadmill at 3.5 m/s. Maximum vertical loading rate and GRF variables were generated. Sample entropy of GRF during the first 20% of the stance phase was calculated to assess GRF complexity. Age and shoe type did not significantly affect the maximal loading rate and GRF. Older participants exhibited higher anteroposterior and vertical GRF sample entropy compared to younger runners. In conclusion, the amplitudes of GRF were not influenced by age group, which indicated that muscle strength in the older runners tested could fulfil mechanical demand (e.g., shock absorption, force generation) during running. However, the increased GRF complexity in initial stance phase with ageing could be a result of reduced muscle contraction coordination and smoothness of force production.

PERBEDAAN EFEKTIVITAS PEMBERIAN PISANG RAJA DAN PISANG AMBON TERHADAP INDEKS KELELAHAN OTOT ANAEROBIK PADA REMAJA DI SEKOLAH SEPAK BOLA

Background : Anaerobic muscle fatigue occurs due to accumulation of lactic acid, causing soreness and reduced muscle contraction. Raja banana (Musa paradisiaca var. Sapientum L.) and Ambon banana (Musa paradisiaca var. Sapientum (L.) Kunt.) are high in carbohydrate and potassium which are involved in increasing blood glucose, thus consuming bananas before exercising may help prevent muscle fatigue.This study aimed to determine the effectiveness of Raja and Ambon bananas on anaerobic. muscle fatigue index of adolescents in football school.Methods :This study was a quasi-experimentusingthe posttest-only with control group design.Thirty-nine male adolescents aged 15-18 years at Terang Bangsa and Satria Kencana Serasi football schools were recruited and classified into 3 groups: control (240 ml of mineral water), group I (150 g Raja banana fruit), and group II (150 g of Ambon banana fruit). Anaerobic muscle fatigue was measured by Running-base Anaerobic Sprint Test (RAST) to calculate Anaerobic Fatigue (AF) value. Data were analyzed by One way ANOVA and ANCOVA test.Results :The average AF index in control group (11.53±2.20) was significantly different with group I (4.30±0.80; p=0.001), and group I with group II (9.76 ± 2.34; p=0,001). However not significantly different between the averageAF Index of control group withgroup II.Conclusion :There is a significant difference in the effectiveness of Raja and Ambon banana on reducing anaerobic muscle fatigue for adolescents in football school. Raja banana demonstratedbetter effects on muscle fatiguein comparison withAmbon banana.

Lower working heights decrease contraction intensity of shoulder muscles in a herringbone 30° milking parlor

Musculoskeletal disorders have been a main concern in milkers for many years. To improve posture, a formula was developed in a previous study to calculate ergonomically optimal working heights for various milking parlor types. However, the working height recommendations based on the formula for the herringbone 30° parlor were broad. To clarify the recommendations for the optimal working height, we investigated the effect of working height on upper limb and shoulder muscle contraction intensities. We evaluated 60 milking cluster attachment procedures in a herringbone 30° milking parlor in 7 men and 9 women. Specifically, we examined the effect of working height on muscle contraction intensity of 4 arm and shoulder muscles bilaterally (flexor carpi ulnaris, biceps brachii, deltoideus anterior, and upper trapezius) by using surface electromyography. The working heights (low, medium, and high), which reflect the ratio of the subject's height to the height of the udder base, were used in the milking health formula to determine and fit individual depth of pits. Data were evaluated for each muscle and arm side in the functions holding and attaching. Statistical analysis was performed using linear mixed effects models, where muscle contraction intensity served as a target variable, whereas working height coefficient, sex, subject height, and repetition were treated as fixed effects, and repetition group nested in working height nested in subject was considered a random effect. Contraction intensities decreased with decreasing working height for the deltoideus anterior and upper trapezius, but not for the flexor carpi ulnaris or the biceps brachii muscles in both holding and attaching arm functions. We found that milking at a lower working height reduced muscle contraction intensities of the shoulder muscles. Women showed higher contraction intensities than men, whereas subject height had no effect. The study demonstrated that a lower working height decreased muscular load during milking. These lower working heights should be used within the recommendations made by the milking health formula for the herringbone 30°. Working heights could be adjusted effectively for milkers of varying body height. Future studies should therefore use the milking health formula as a tool to objectively compare and improve the accuracy of the working height coefficients.

Clinical Research: Good News Coming from Ca2+/cAMP Signaling Interaction

Clinical research plays an important role in medical sciences by determining the safety and efficiency of medications, devices and diagnostic products for human use. Our discovery of the interactions between intracellular signaling pathways as mediated by Ca2+ and cAMP (Ca2+/cAMP signaling interaction) in neurotransmission could help improve clinical research. This discovery emerged from classical neurotransmission studies using rodent vas deferens as a model. In addition, the concept of Ca2+-dependent muscle contraction (Ca2+ influx triggers muscle contraction) is amply accepted. Thus, Ca2+ channel blockers (CCB) should reduce muscle contraction. Nonetheless, using this model, some studies performed since 1975 reported that reduction of Ca2+ influx by low concentrations of CCB (verapamil, diltiazem or nifedipine) produced a paradoxical increase of the contractions mediated sympathetic nerves, a phenomenon known as “calcium paradox”. Recent studies using adrenal chromaffin cells have also demonstrated that CCB caused a paradoxical increase of the catecholamine release. Because these compounds are blocking the L-type voltage-activated Ca2+ channels (VACC), an augmented nerve-mediated response due to increased neurotransmitter release was an unexpected outcome. In 2013, we revealed that the Ca2+/cAMP signaling interaction could properly explain the so-called “calcium paradox”. The original paper published by us in Cell Calcium (2013) has appeared four times in ScienceDirect TOP 25 Hottest Articles lists. In conclusion, these findings may significantly impact on cardiovascular and neurodegenerative diseases, cancer, stem cell-based therapies and many other diseases, and may stimulate the development of new pharmacological strategies to combat these diseases.

A botulinum neurotoxin-like function of Potentilla chinensis extract that inhibits neuronal SNARE complex formation, membrane fusion, neuroexocytosis, and muscle contraction

Context: Botulinum neurotoxins (BoNTs) are popularly used to treat various diseases and for cosmetic purposes. They act by blocking neurotransmission through specific cleavage of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. Recently, several polyphenols were shown to interfere with SNARE complex formation by wedging into the hydrophobic core interface, thereby leading to reduced neuroexocytosis.Objective: In order to find industrially-viable plant extract that functions like BoNT, 71 methanol extracts of flowers were screened and BoNT-like activity of selected extract was evaluated.Materials and methods: After evaluating the inhibitory effect of 71 flower methanol extracts on SNARE complex formation, seven candidates were selected and they were subjected to SNARE-driven membrane fusion assay. Neurotransmitter release from neuronal PC12 cells and SNARE complex formation inside the cell was also evaluated. Finally, the effect of one selected extract on muscle contraction and digit abduction score was determined.Results: The extract of Potentilla chinensis Ser. (Rosaceae)(Chinese cinquefoil) flower inhibited neurotransmitter release from neuronal PC12 cells by approximately 90% at a concentration of 10 μg/mL. The extract inhibited neuroexocytosis by interfering with SNARE complex formation inside cells. It reduced muscle contraction of phrenic nerve-hemidiaphragm by approximately 70% in 60 min, which is comparable to the action of the Ca2+-channel blocker verapamil and BoNT type A.Discussion and conclusion: While BoNT blocks neuroexocytosis by cleaving SNARE proteins, the Potentilla chinensis extract exhibited the same activity by inhibiting SNARE complex formation. The extract paralyzed muscle as efficiently as BoNT, suggesting the potential versatility in cosmetics and therapeutics.

Cholinergic regulation of body-wall muscle contraction of the ascidian Styela rustica (Linnaeus, 1767)

The regulation of body-wall muscle contraction in the ascidian Styela rustica was studied. Acetylcholine (ACh, 1–10 μM) induced a significant contraction of isolated muscle strips. The ACh-induced contractile response was potentiated and prolonged in the presence of proserine (15 μM), which confirms acetylcholinesterase activity in the S. rustica body-wall muscle. Atropine (1–100 μM, M-cholinoreceptor blocker) did not prevent the ACh-induced contractile response, while d-tubocurarine (1–100 μM, N-cholinoreceptor blocker) progressively reduced muscle contraction induced by 10 μM ACh. Thus, neuromuscular transmission in the S. rustica body-wall muscle is mediated by nicotinic-like ACh-receptors. Procaine reduced ACh-induced (10 μM) muscle contraction. As well, our experiments showed spontaneous rhythmic contractile activity in isolated muscle strips of S. rustica. Atropine, d-tubocurarine, procaine, and proserine did not alter rhythmic activity. Myogenic automaticity is suggested as a possible cause of the rhythmic contraction of the ascidian body-wall muscle.

Reduced muscle contraction and a relaxed posture during sleep-like Lethargus

Sleep is characterized by reduced muscle activity resulting in reduced movement and a typical posture compatible with relaxed muscles. Prior to each molt, C. elegans larvae go through a phase of behavioral quiescence called Lethargus. Lethargus has sleep-like properties, but a specific posture has not yet been described. Do C. elegans larvae relax their muscles during sleep and do they assume a typical posture? We measured worm posture and body wall muscle activity using calcium imaging across the sleep-wake-like cycle. We found that worms were less curved and had less muscle activity during the sleep-like state. We conclude that during Lethargus, muscle activity is reduced, resulting in a relaxed body posture typical for a sleep-like state.

Sarcopenia in the Caenorhabditis elegans pharynx correlates with muscle contraction rate over lifespan

In muscles, sarcopenia, the loss of muscle mass, is the major cause of aging-related functional decline and frailty. Several factors are correlated with sarcopenia during aging, including contraction-related cellular injury, oxidative stress, endocrine changes and reduced regenerative potential. However the involvement of these factors has not been experimentally investigated. Here, we report that contraction-related injury may significantly promote the progression of sarcopenia in the pharynx of the nematode, Caenorhabditis elegans, a model of aging in non-regenerative tissues. Both functional and structural declines in the pharynx during aging were significantly delayed in mutants with reduced muscle contraction rates. We also examined the role of bacteria in pharynx muscle decline during aging, as previous studies reported that antimicrobial treatments could extend C. elegans lifespan. Although microbial infection may have enhanced functional decline in the pharynx during aging, it was not the sole cause of decreased pumping rates in old animals. This study identifies contraction-related injury as a factor affecting the initiation and progression of sarcopenia during aging. Further, characterization of the specific types of damage induced by muscle contraction will be helpful for understanding the underlying causes of sarcopenia.

Evidence for modulation of smooth muscle force by the p38 MAP kinase/HSP27 pathway.

Mitogen-activated protein (MAP) kinases signal to proteins that could modify smooth muscle contraction. Caldesmon is a substrate for extracellular signal-related kinases (ERK) and p38 MAP kinases in vitro and has been suggested to modulate actin-myosin interaction and contraction. Heat shock protein 27 (HSP27) is downstream of p38 MAP kinases presumably participating in the sustained phase of muscle contraction. We tested the role of caldesmon and HSP27 phosphorylation in the contractile response of vascular smooth muscle by using inhibitors of both MAP kinase pathways. In intact smooth muscle, PD-098059 abolished endothelin-1 (ET-1)-stimulated phosphorylation of ERK MAP kinases and caldesmon, but p38 MAP kinase activation and contractile response remained unaffected. SB-203580 reduced muscle contraction and inhibited p38 MAP kinase and HSP27 phosphorylation but had no effect on ERK MAP kinase and caldesmon phosphorylation. In permeabilized muscle fibers, SB-203580 and a polyclonal anti-HSP27 antibody attenuated ET-1-dependent contraction, whereas PD-098059 had no effect. These results suggest that ERK MAP kinases phosphorylate caldesmon in vivo but that activation of this pathway is unnecessary for force development. The generation of maximal force may be modulated by the p38 MAP kinase/HSP27 pathway.

Molecular basis of altered contractility in experimental colitis: expression of L-type calcium channel.

Colitis in experimental animals or idiopathic inflammatory bowel disease, such as ulcerative colitis or Crohn's disease in humans, is associated with reduced muscle contraction. This is predicted to be due to disturbance of Ca2+ homeostasis in the inflamed muscle cell. However, the underlying molecular mechanism remains to be elucidated. Since the catalytic alpha-1 subunit of the L-type Ca2+ channel regulates Ca2+ influx, levels of the alpha-1 mRNA and protein were examined. Colitis induced by intrarectal administration of trinitrobenzenesulfonic acid was monitored by measuring the myeloperoxidase activity and histology. The levels of mRNA and protein were estimated using RT-PCR and immunoblotting. Myeloperoxidase activity increased in the inflamed colon, and the lamina propria and muscle layers showed infiltration of inflammatory cells and loss of crypts. Two alternatively spliced alpha-1 mRNA isoforms were detected in the colonic muscle. The ratio of unspliced to spliced mRNA isoforms remained unaltered in inflamed muscle. In contrast, the level of corresponding protein isozymes decreased in the colitic animals. Thus colitis-induced reduction in the alpha-1 protein may account for the reduced colonic contractility seen in colitis.

Inhibitory effects of glucose utilization by gymnema acids in the guinea-pig ileal longitudinal muscle

Two substances identified as ((3 beta, 4 alpha, 16 beta, 21 beta, 22 alpha)-21-tigloxy-16, 22, 23, 28-tetrahydroxyolean-12-en-3-yl-beta D-glucopyranosiduronic acid) (GA1) and ((3 beta, 4 alpha, 16 beta, 21 beta, 22 alpha)-21-(2-methylbutyroxy)-16, 22, 23, 28-tetrahydroxyolean-12-en-3-yl-beta-D-glucopyranosiduronic acid) (GA2) identified among the gymnemic acids are triterpene glycosides extracted from Gymnema sylvestre leaves. We examined the effects of GA1 or GA2 on high K(+)-induced contraction in the guinea-pig longitudinal muscle. A sustained muscle contraction induced by hyperosmotically added 65.4 mM KCI (H-65K+) was suppressed by GA1 or GA2 (7.7 x 10(-5) M). Simultaneous measurements of reduced pyridine nucleotide (PNred) or oxidized flavin protein (FPox) by the fluorescence technique and of contractile force revealed that GA1 and GA2 reduced the increase of PNred fluorescence and contractile force induced by H-65K+, whereas FPox fluorescence induced by it further increased. Reduced muscle contraction induced by GA1 or GA2 was restored by 5.5 mM pyruvate. Simultaneous measurements of intracellular Ca2+ [Ca2+]1 level and contractile force indicated that [Ca2+]1 level, which increased by H-65K+, hardly changed with GA1 and GA2. In summary, both GA1 and GA2, which are among the gymnemic acids, suppressed high K(+)-induced contraction in the guinea-pig ileal longitudinal muscle. The difference between these two gymnemic acids was not significant. The inhibitory effect of GA1 and GA2 on smooth muscle were assumed to be a result of inhibiting glucose uptake, which is an energy source of the muscle, whereas the inhibitory mechanisms were probably not mediated by Ca2+.

Analysis of ciliary beat frequencies in hamster oviducal explants.

We have developed a simple direct method, requiring minimal manipulation, to measure beat frequencies of the cilia on the external surface of hamster oviducal infundibula in vitro. Two perfusion chambers (closed and open) were used; both can be hand-made in a few minutes and discarded after use. Ciliary beat frequencies were determined by measuring variations in light intensity with time in a single pixel positioned over a video image of the beating cilia. Data files were collected using Image 1 software and later transferred to PSI Plot or Lotus 123 spreadsheets for analysis by counting the number of brightness peaks recorded per second or by subjecting the data to Fourier transformation with or without smoothing. These methods of analysis gave similar results. To verify that Image 1 data files contain accurate representations of CBF, videotapes of beating cilia were made and subjected to frame-by-frame analysis. Image 1 interfaced with a standard video camera was found to collect reliable data over a beat frequency range of 0-15 cycles/sec. In some Fourier transforms, secondary peaks were observed and were shown to represent cilia beating at more than one frequency in a sampled region. Coefficients of variation for repeated measurements taken on the same region varied from 4.1% to 9.0%. Small but significant differences were found between beat frequencies at different regions of the same oviduct. When chambers were perfused discontinuously and measurements of beat frequency were made at least 5 min after each perfusion, no effect of perfusion on frequencies was observed. However, during continual perfusion of the open chamber, a slight but significant increase in beat frequency was observed after perfusion was initiated. Muscle contraction, which sometimes occurs in the open chamber, did not affect beat frequency measurements. Infundibula could be stored at 4 degrees C overnight without any negative effect on beat frequencies. Cold storage also reduced muscle contraction. Placement of a small coverslip on infundibula in the open chambers was also found to reduce muscle contraction and facilitate beat frequency measurements. Coverslipping did not affect beat frequencies. This method of beat frequency analysis will be valuable for analyzing factors that regulate or influence cilia in mammalian oviducts.