Oxide Release Research Articles

Effects of a static magnetic field on proliferation, apoptosis and secretion in human umbilical cord endothelial cells

Objective To evaluate the effects of static magnetic fields (SMFs) of different intensity and exposure duration on the proliferation and apoptosis of human umbilical cord endothelial cells (HUVECs),and their release of nitric oxide (NO),6-keto-prostacyclin 1α (6-keto-PGF1α) and endothelin (ET-1).Methods Cultured HUVECs were exposed to a SMF at 5,22,86 or 135 mT for 8,12 or 24 hours.Their proliferation and apoptosis were monitored by flow cytometry (FCM).The medium was collected to test its NO content by optical density.ET-1 and 6-keto-PGF1α were measured by radioimmunization.Results ( 1 ) The proliferation of HUVECs increased when the cells were exposed to a SMF at 5 mT for 8 h,but a SMF at 135 mT for 12 h or 24 h inhibited the proliferation of HUVECs.(2)An SMF had no effect on apoptosis of HUVECs.(3)An SMF at 5 mT for 8 h increased the release of NO and 6-keto-PGF1 a,but the release of NO and 6-keto-PGF1 a decreased when the SMF intensity was 135 mT or the cells were exposed to an SMF for 12 h or 24 h.(4) An SMF at 5 mT or 22 mT for 8 h did not effect the release of ET-1.An SMF at 86 mT or 135 mT increased the release of ET-1.Compared with a control group,an SMF at 5 mT for 12 or 24 h did not affect the release of ET1,but at 22,80 or 135 mT,the release of ET-1 decreased significantly.Conclusions Exposure to a low intensity SMF for a short duration could improve the proliferation of HUVECs and increase the release of vasoactive factors,but if HUVECs are exposed to a strong SMF or exposed for a long duration,the proliferation and the release of vasoactive factors is decreased. Key words: Static magnetic fields; Endothelial cells; Nitric oxide; Endothelin-1; 6-keto-prostacyclin 1 α

Plasma nitrite/nitrate levels in women with postmenopausal hot flushes

ABSTRACTAim To study a possible association between the potent vasodilatory nitric oxide and postmenopausal hot flushes.Methods We compared the release of nitric oxide in 150 recently menopausal women reporting no (n = 23), mild (n = 34), moderate (n = 30), or severe (n = 63) hot flushes. Plasma samples, collected after a 48-h arginine-poor diet, were assessed for the metabolites of nitric oxide (NOx), using the Griess reaction.Results Levels of NOx showed no association with the severity of hot flushes. Furthermore, no relationships with individual hot flushes and serum levels of estradiol or high-sensitivity C-reactive protein were detected.Conclusions These preliminary data indicate that nitric oxide appears not to be a factor in hot flushes and might not be related to their etiology. Since a fasting plasma NOx measurement may not reflect what happens at the time of the hot flush episode, in future studies there should be an attempt to assess nitric oxide release during a concomitant hot flush.

Effects of Ginkgo biloba extract on the expression of eNOS and the release of NO in mesenteric arterioles of senile rats

To investigate the effects of Ginkgo biloba extract (GBE) on the expression of endothelial nitric oxide synthase (eNOS) and the release of nitric oxide (NO) in mesenteric arterioles of aging rats. (1) Cytologic experiment:human umbilical vein endothelial cells (HUVEC) were randomly divided into 3 groups: control group, NG-nitro-L-arginine methyl ester (L-NAME) group and GBE group. L-NAME group: 100 µmol/L L-NAME was added into HUNEC for a 48-hour incubation. GBE group: After HUVEC was exposed to 100 µmol/L L-NAME for 24 hours, 20 g/L GBE was added for another 24-hour co-incubation. Then the expression of eNOS protein was observed in each group. (2) Animal experiment: Thirty-two 24-month-old male SD rats were randomly divided into normal control group (n = 8) and GBE group (n = 24). The GBE group was further divided into 3 groups receiving an orally dosed GBE for 3, 5, 7 days respectively. Afterward the diameter of first-order mesenteric arteriole was measured under the pressures of 20, 40, 60, 80, 100, 120, 140 mm Hg (1 mm Hg = 0.133 kPa) and the elasticity of blood vessels calculated. The release of NO, the expression of eNOS protein and its mRNA in mesenteric arterioles stimulated by the same shear stress (15 dyn/cm(2)) were evaluated respectively. (1) Cytological studies indicated that the expression of eNOS protein of the L-NAME group was significantly lower than those of the control and GBE groups (0.57 ± 0.06 vs 0.96 ± 0.05, 0.81 ± 0.09, both P < 0.01). (2) After the dosing of GBE for 3, 5, 7 days, the release of NO was significantly higher than that of the control group [(8.01 ± 0.24, 12.11 ± 0.78, 14.72 ± 0.70 vs 5.83 ± 0.75) pmol×mm(-2)×min(-1), all P < 0.05]; the expressions of eNOS protein were significantly higher than those of the control group (0.59 ± 0.20, 0.86 ± 0.02, 1.09 ± 0.13 vs 0.41 ± 0.16, all P < 0.05). And GBE was highest at Day 7; the expression levels of eNOS mRNA were significantly higher than those of the control group (0.79 ± 0.04, 0.85 ± 0.07, 0.99 ± 0.03 vs 0.58 ± 0.05, all P < 0.05). And GBE was also highest at Day 7. GBE can improve vascular flexibility through increasing the expression of eNOS and the release of NO, protecting the functions of blood vessels.

Nitric oxide-releasing nanoparticle combination therapy to overcome drug resistance in platinum-resistant breast cancers.

278 Background: The most successful cancer chemotherapy regimens usually involve the administration of multiple cytotoxic agents simultaneously. Because different chemotherapies may have different mechanisms of action; it is difficult for cancer cells to become resistant to combination therapy. Recent investigations have discovered that nitric oxide (NO) may be involved in the reversal of cisplatin (CDDP) resistance in chemotherapy. Therefore, we sought to develop a combination regimen involving a NO-releasing prodrug (NO1) and cisplatin for the treatment of breast cancer. Methods: The prodrug NO1 was synthesized to be localized in tumor cells and to release nitric oxide over 10 hours. The antiproliferative activity of NO1 was determined in human breast cancer cell line, MDA-MB-468LN. To evaluate the effectiveness of the CDDP/NO combination regimen, platinum-resistant MDA-MB-468LN cells were treated with either cisplatin alone ([CDDP]=0.01, 0.02 or 0.03 mM) or the CDDP/NO combination ([CDDP]=0.01, 0.02 or 0.03 mM; [NO1]=0.02 mM). The cell viability was determined 48 hours post-treatment using a live/dead trypan blue exclusion assay. Results: The toxicity to breast cancer cells was higher than JS-K, a systemic NO agent currently in preclinical development. (NO1: IC50=26µM; JS-K: IC50=42 µM). In addition, NO1 had a long sustained release of nitric oxide, approximately one fold longer than JS-K (NO1: t1/2=6 h; JS-K: t1/2=3 h). The combination treatments resulted in 6.6-, 6.9- and 7.5-fold increase in cell death compared to cisplatin treatment alone at cisplatin concentrations of 0.01, 0.02 and 0.03 mM, respectively. A subsequent study in a murine xenograft of head and neck cancer found NO-1 conjugated to nanoparticles increased survival a mean of 10 weeks compared to controls (p&lt;0.0001). Conclusions: Nitric oxide prodrug NO-1 and nanoparticles of it have high anticancer activity in vivo and they can reverse platinum resistance in vitro. Ongoing studies are examining the safety and efficacy of CDDP/NO combination therapy in mouse xenografts of human breast cancer.

Modern views on amlodipine and new S-amlodipine medications

The review presents the latest evidence on the calcium antagonist amlodipine, summarizing its mechanisms of action, its pleiotropic, endothelial function-related effects, and its anti-atherogenic activity. Amlodipine suppresses the proliferation of vascular smooth myocytes and extracellular matrix and improves endothelial vasodilatation, despite the absence of L-type calcium channels in these cells. This mechanism is related to an increase in endothelial nitric oxide (NO) release. The results of experimental studies on the role of S and R amlodipine isomers in its hemodynamic and pleiotropic activity are presented. While S-amlodipine is a pharmacologically active blocker of L-type calcium channels, R-amlodipine increases endothelial NO release. New medications have been developed, based on S-amlodipine. It has been shown that S-amlodipine 5 mg/d is bioequivalent to amlodipine 10 mg/d. The pharmacodynamics analysis demonstrated that S-amlodipine 5 mg/d and amlodipine 10 mg/d did not differ significantly in terms of mean levels of systolic and diastolic blood pressure, or mean heart rate. S-amlodipine was better tolerated and characterised by a lower incidence of peripheral edema than amlodipine. However, the effects of S-amlodipine on hard end-points should be investigated in the long-term prospective studies.

Transient Ischemic Attack Associated With Trazodone Therapy

To the Editor: Trazodone is a tetracyclic antidepressant commonly prescribed for insomnia. We report the emergence of neurologic symptoms suggestive of transient ischemic attack (TIA) in a patient following the initiation of trazodone. To the best of our knowledge, no reports of such an occurrence have been published. Case report. Mr A, a 40-year-old man with a history of mood disorder not otherwise specified (DSM-IV criteria), was admitted to a psychiatric inpatient unit in 2010 for suicidal ideation and depressed mood. He developed depressive symptoms about a year prior to this presentation when he got laid off from his job of over 4 years. Mr A had attempted suicide twice in the preceding year (the first time, he attempted to asphyxiate himself, and the second time, he overdosed on hydrocodone tablets) and was hospitalized at a psychiatric inpatient unit on both occasions. During his most recent admission (2 months prior to this presentation), he was started on fluoxetine treatment, which he discontinued after discharge. The stressors precipitating his current admission included homelessness, unemployment, financial constraints, and impending divorce. He endorsed depressed mood, decreased interest, poor energy, sleep difficulties, poor appetite, and suicidal ideation with a plan to stab himself. He denied auditory or visual hallucinations, psychotic symptoms, and drug or alcohol abuse. He had experimented with cocaine and marijuana during high school. There was no evidence of homicidal ideation or delusions. His medical history was significant for irritable bowel syndrome and tinnitus. Findings of his physical examination were unremarkable, and he was not taking any medications at the time of presentation. He did not tolerate valproic acid and citalopram initiated during this admission. He tolerated lithium carbonate 300 mg 3 times daily but complained of insomnia. He reported a past history of nonresponse to zolpidem. Five days after the admission, he was started on trazodone 50–100 mg at bedtime as needed for insomnia. Twelve hours later, he developed slurred speech, neck pain, facial tingling sensations, vertigo, dizziness, lack of coordination, muscle weakness, blurred vision, and diplopia. His serum lithium level was 0.5 mEq/L. An immediate computed tomography scan of the head was performed, which was negative for hemorrhage or ischemia. He was unable to walk and required wheelchair support. We discontinued trazodone, which led to rapid resolution of all his neurologic symptoms, except for his dizziness, within 24 hours. Neurologic examination on day 2 revealed no abnormalities, but the neurologist recommended magnetic resonance imaging of the brain and angiography of the neck to rule out stroke; findings of both tests were within normal limits. He received a single 325-mg dose of aspirin and was started on meclizine 25 mg/d. His dizziness improved on day 2 after cessation of trazodone therapy. We decided to continue lithium since the serum lithium level was low and all his symptoms resolved. A temporal relationship between drug initiation and emergence of neurologic symptoms and, most importantly, complete remission on discontinuation suggests TIA possibly as an adverse event following trazodone use. The literature shows that serotonergic drugs cause cerebral vasoconstriction. Paroxetine, a selective serotonin reuptake inhibitor (SSRI), has caused TIA and stroke.1–3 It was postulated that paroxetine and other SSRIs may result in changes of the vasculature and subsequent ischemic events in predisposed patients.1 Normally, serotonin secreted by platelets stimulates 5-HT2A receptors, which mediate vasoconstriction. This is counterbalanced by the release of the vasodilator nitric oxide upon serotonin stimulation of endothelial 5-HT1 receptors. In addition to their serotonergic activity, SSRIs such as paroxetine weakly inhibit norepinephrine reuptake and nitric oxide production, which increases the risk of cerebrovascular events.1 The combination of lithium, trazodone, and paroxetine as well as the combination of lithium, trazodone, and bupropion has been implicated in stroke.2 It is possible that the combination of lithium and trazodone in our patient has a role in the evolution of vasoconstriction, given their serotonergic effects. Similarly, ergot derivatives, amphetamine, and cocaine cause stroke due to their sympathomimetic and serotonergic effects.4 Trazodone possibly increases the serotonin release from platelets by its antagonistic and reuptake inhibitor effect at serotonin receptor, which may cause vasoconstriction. Trazodone has an effect on vascular and coagulation system like that of SSRIs, which may implicate that trazodone is associated with cerebrovascular accidents. Our case emphasizes that when vasoconstriction is suspected, serotonergic drugs should be discontinued.

Wine Pigments: From Your Cup to Your Cells

Anthocyanins are among the various bioactive components of wines to which health-promoting effects are ascribed. Their bioavailability is however very limited, as shown by post-absorption plasma concentration values of 10-9–10-8 M. The cardiovascular system is one of the main targets of anthocyanin bioactivity. The presence of the membrane transporter bilitranslocase (T.C. 2.A.65.1.1) in the vascular endothelium allows the transport of wine anthocyanins from the blood into the cells. Here anthocyanins can trigger further biological responses, ending with the release of nitric oxide, a powerful factor of cardiovascular protection.

Hypoxia: just say NO?

Hypoxia: just say NO?

Dynamics of neuron-glia interplay upon exposure to unconjugated bilirubin

Microglia are the main players of the brain immune response. They act as active sensors that rapidly respond to injurious insults by shifting into different activated states. Elevated levels of unconjugated bilirubin (UCB) induce cell death, immunostimulation and oxidative stress in both neurons and astrocytes. We recently reported that microglial phagocytic phenotype precedes the release of pro-inflammatory cytokines upon UCB exposure. We investigated whether and how microglia microenvironment influences the response to UCB. Our findings revealed that conditioned media derived from UCB-treated astrocytes reduce microglial inflammatory reaction and cell death, suggesting an attempt to curtail microglial over activation. Conditioned medium from UCB-challenged neurons, although down-regulating tumor necrosis factor-α and interleukin-1β promoted the release of interleukin-6 and nitric oxide, the activation of matrix metalloproteinase-9, and cell death, as compared with UCB-direct effects on microglia. Moreover, soluble factors released by UCB-treated neurons intensified the phagocytic properties manifested by microglia under direct exposure to UCB. Results from neuron-microglia mixed cultures incubated with UCB evidenced that sensitized microglia were able to prevent neurite outgrowth impairment and cell death. In conclusion, our data indicate that stressed neurons signal microglial clearance functions, but also overstimulate its inflammatory potential ultimately leading to microglia demise.

Anti-inflammatory and antiulcerogenic activities of leaf extracts and sesquiterpene from Teucrium ramosissimum (Lamiaceae)

Teucrium ramosissimum (Lamiaceae) is a native and endemic medicinal plant from South of Tunisia traditionally used for the treatment of many diseases. The anti-inflammatory and antiulcerogenic activities of sesquiterpene (β-eudesmol), chloroform, and ethyl acetate leaf extracts from T. ramosissimum were assayed. Macrophage phagocytic activity and lymphocyte proliferation in the absence and presence of mitogens (lipopolysaccharide [LPS] or lectin) were investigated. Depending on the concentrations, the extracts affect macrophage functions by modulating their lysosomal enzyme activity and nitric oxide (NO) release. For lymphocyte proliferation assay, tested extracts enhance significantly cell proliferation either with or without mitogen stimulation. These results suggest that leaf extracts from T. ramosissimum contain potent components such as flavonoids that may be potentially useful for modulating immune cell functions in physiological and pathological conditions. Antiulcerogenic activity was examined on rat ethanol-induced ulcerogenic model. Compared with control (cimetidine), leaf extracts from T. ramosissimum exert different protective effects against ethanol-induced ulcerogenesis.

The mechanistic studies of acupuncture and moxibustion in Taiwan

Traditional Chinese acupuncture has a history of over 2500 years. It is effective in the treatment of many conditions with few side effects. The best known mechanism is via endogenous opiates and their receptors. In addition to opioids, researchers have focused on the role of central monoamimergic systems. Acupuncture therapy is used not only to relieve pain but also to treat various medical conditions in traditional Chinese medicine (TCM). Some experiments have revealed a relationship between acupuncture and the autonomic nervous system (ANS). Besides, electroacupuncture (EA) can modulate the imbalance between innate and acquired immune systems. This review is focusing on the mechanistic studies of acupuncture that my colleagues and I have performed in Taiwan in recent years. We found that EA analgesia was closely related to not only the serotonergic neurons but also the adrenergic neurons in the central nervous system. The electrophysiological recordings suggested the involvement of the cerebral cortex in acupuncture. Local somatothermal stimulation inhibited the motility of sphincter of Oddi and internal anal sphincter through nitrergic neural release of nitric oxide. Mild local heat stress upregulated hepatic gene expression of heat shock protein 70 and protected the liver from subsequent ischemia-reperfusion injury. These studies supplement the knowledge of the mechanism of acupuncture.

Electroacupuncture Zusanli (ST36) on Release of Nitric Oxide in the Gracile Nucleus and Improvement of Sensory Neuropathies in Zucker Diabetic Fatty Rats

The purpose of these studies was to examine the effects of electroacupuncture (EA) Zusanli (ST36) on release of nitric oxide (NO) in the gracile nucleus (GN) and determine if functional neuropathic changes were modified by EA ST36-induced NO in the nucleus in Zucker diabetic fatty (ZDF) rats. The foot withdrawal responses to mechanical, thermal and cold stimuli were measured before and after EA stimulation. A microdialysis probe was implanted in the GN and dialysate samples were collected 20 min before, during and after EA ST36. Total nitrate and nitrite (NOx −) concentrations in the samples were quantified by using chemiluminescence. The baseline dialysate NOx − concentrations in the GN were decreased in ZDF rats compared to lean control (LC) rats (P < .05). In ZDF rats, dialysate NOx − releases in the GN were markedly increased during EA ST36, whereas in LC rats, the releases were moderately enhanced at 20–40 min after EA ST36. The withdrawal latencies to mechanical, cold and thermal stimuli were significantly improved 20 min after EA ST36 both in LC and ZDF rats, but not altered by non-acupoint stimulation. The withdrawal latencies to EA ST36 were further potentiated by 3-morpholinyl-sydnoneimine and inhibited by NG-Propyl-l-arginine infused into the GN in ZDF rats (P < .05). These results show that EA ST36 increases NO release in the GN, and NO in the nucleus modifies withdrawal latencies to mechanical, cold, and thermal nociception stimuli. Data suggest that EA ST36 induces NO release in the GN, which contributes to improvement of sensory neuropathies in rats.

Stress Response by Bone Cells and Implications on Microgravity Environment

Osteocytes are commonly referred to as the professional mechanosensors in bone tissue. Despite recent advances in the study of how bone tissue adapts to mechanical loading, much remains not understood concerning the cellular mechanisms involved. We have shown that bone cell monolayers in vitro release signaling molecules in response to dynamic stress loading in a rate-dependent manner. Fluid shear stress induces high release of nitric oxide (NO) at high rates, whereas vibration stress promotes high NO release but low prostaglandin E2 (PGE2) release at high rates, indicating the specificity for signaling molecule of the type of stress. Also, we show evidence that bone cells require a stress threshold in order to respond to loading. These observations collectively provide basis for hypothesizing a model defining tissue-mimetic mechanosensitivity as a function of the rate of stress above a threshold. Finally, at the cellular level, we show that shape and stiffness, evidently due to underlying cytoskeletal structure, contribute to mechanosensing. This leads to the notion that the mechanical properties of cells are a prerequisite to their tissue-level emergent mechanosensing behavior. Therefore, a condition of disturbed mechanics due to extreme unloading, as in an environment under microgravity, may lead to impaired mechanosensing.

INHIBITION OF MORPHINE TOLERANCE WITHIN THE RAT NUCLEUS ACCUMBENS BY NITRIC OXIDE

The role of glutamate receptors within the nucleus accumbens in morphine tolerance has been postulated. Previous studies have reported that glutamate receptors exert their effects in part through the release of nitric oxide (NO). In the present study, the effect of intra-accumbal injections of L-arginine, the NO precursor and L-NAME, the NOS inhibitor on the morphine tolerance in Wistar rats (250-300 g) were investigated. For this purpose, male rats (n = 8/group) were anesthetized and bilateral cannulation (23-gauge, AP=1.7mm, L=±0.8, V= 7.1 mm) was performed into nucleus accumbens. Five days after cannulation, animals were trained in an Un-Biased conditioned place preference apparatus for five consecutive days. The NOergic drugs were injected in two ways: first; the animals were trained with morphine and were received L-arginine or L-NAME at 5th day of experiments just before the test. Second group received L-arginine or L-NAME before morphine injection. At the 5th day of the experiments, each animal was placed in the apparatus and its behavior was recorded for 10 min. The results showed that pretreatment of the animals with L-arginine did not produce any effect on morphine tolerance. Pretreatment of the animals with L-NAME potentiated both development and expression of morphine tolerance. In conclusion, present experiments showed that morphine tolerance is in part dependent on activation of NO system within the nucleus accumbens and the role of this neuromodulator in morphine dependence must be considered in further treatments of morphine addicts.

Nitric oxide mediation of morphine sensitization in the rat nucleus accumbens

Previous studies have reported that morphine exerts its effects in part through the release of nitric oxide (NO). It has been pustulated that drug sensitization is a major cause of relapse to drug use in addicts. In the present study the effects of intra-accumbal injections of L-arginine, the NO precursor and L-NAME, the NOS inhibitor on the morphine sensitization in Wistar rats (250-300 g) were investigated. Male rats (n = 8/group) were anesthetized and bilateral cannulation in nucleus accumbens (23-gauge, AP = 1.7mm, L = ±0.8, V = 7.1 mm) was performed. Five days after cannulation, animals were trained in an Un-Biased conditioned place preference apparatus for five consecutive days. The NOergic drugs were injected to the animals in two ways: first; the animals were trained with morphine and were received L-arginine or L-NAME at 5th day of experiments just before the test. Second group received L-arginine or L-NAME before morphine injection. At the 5th day of the experiments, each animal was placed in the apparatus and its behavior was recorded for 10 min. The results showed that pretreatment of the animals with L-arginine augments the development, but reduced the expression of morphine sensitization. Pretreatment of the animals with L-NAME reduced both development and expression of morphine sensitization. In conclusion, present experiments showed that morphine sensitization is in part dependent on the activation of NO system within the nucleus accumbens and the role of this neuromodulator in morphine dependence must be considered in further treatments of morphine addicts.

Effectiveness of a Custom-fitted Flange and Local Exhaust Ventilation (LEV) System in Controlling the Release of Nanoscale Metal Oxide Particulates During Reactor Cleanout Operations

As the nanotechnology industry expands, facilities engaged in the production and use of engineered nanoscale materials (ENMs) are challenged with determining whether their processes pose a risk for worker inhalation exposure. Although there are neither regulatory exposure limits specific to ENMs nor validated measurement standards for nanomaterials in the workplace, many facilities opt to be proactive in managing uncharacterized ENMs by reducing or eliminating the potential for exposure by controlling their release into the workplace atmosphere. A field study was conducted to evaluate the effectiveness of a portable, HEPA-filtered, local exhaust ventilation system equipped with a custom-fitted flange for controlling the emission of engineered nanoscale metal oxide particulates during reactor cleanout operations. On the basis of the findings of this study, it appears that a properly designed LEV system, coupled with good work practices can be highly effective in controlling nanoscale material emissions during processes of this type.

LOW-INTENSITY ULTRASOUND INCREASES THE ENDOTHELIAL NITRIC OXIDE SYNTHASE (eNOS) EXPRESSION OF ENDOTHELIAL CELLS POSSIBLY VIA THE PHOSPHATIDYLINOSITOL 3-KINASE/AKT/PROTEIN KINASE A SIGNALING PATHWAY

The stimulative effects and the associated mechanism of low-intensity ultrasound on endothelial cells were investigated in this study. Human umbilical cord endothelial cells (HUVECs) were exposed to 1 MHz pulsed ultrasound at 34 mW/cm2for 10 min daily. The cell proliferation, nitric oxide release, intracellular calcium concentration, and endothelial nitric oxide synthase (eNOS) gene and protein expressions after ultrasound exposure were analyzed. It was found that ultrasound exposure did not change the cell proliferation, but it enhanced the release of nitric oxide and Ca2+ions, and increased the eNOS activity. The induced phosphorylation of eNOS (Ser1177) by the ultrasound exposure was inhibited by the addition of N-[2-(p-bromocinnamylamino) ethyl]-5-isoquinoline sulfonamide (H89, a protein kinase A inhibitor), but not 2-(4-morpholino)-8-phenyl-4H-1-benzopyran-4-one hydrochloride (LY294002, a phosphoatidylinositol 3-kinase inhibitor). The induced phosphorylation of Akt (protein kinase B, Ser473) by the ultrasound exposure was inhibited by the addition of LY294002, but not by the presence of H89. The results also applied to bovine carotid artery endothelial cells (BAECs) exposed to ultrasound at a larger intensity (68 mW/cm2). The above experiments suggested that low-intensity ultrasound may promote eNOS activity of endothelial cells via the phosphatidylinositol 3-kinase/Akt/protein kinase A signaling pathway. This may have implications on the therapeutic effect of ultrasound in tissue repair.

Involvement of inducible nitric oxide synthase and cyclooxygenase-2 in the anti-inflammatory effects of a red orange extract in human chondrocytes

In the present study, a complex of compounds (red orange complex, ROC), obtained from three red orange varieties (Citrus sinensis varieties: Moro, Tarocco and Sanguinello), containing cyanidin glycosides, hydroxycinnamic acids, flavanone glycosides and ascorbic acid, was screened to discover new lead compounds in the suppression of the production of key molecules released during inflammatory events in interleukin-1β (IL-β) stimulated human primary chondrocytes. The expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX)-2 and intercellular adhesion molecule-1 (ICAM-1), and the release of nitric oxide, prostaglandin (PG)E2 and interleukin-8 (IL-8) were determined. Indomethacin was used as an anti-inflammatory drug reference. ROC acts as a potent inhibitor of iNOS and COX-2 gene expression while also suppressing the production of PGE2 and nitrite in human chondrocytes. In addition, ROC induces a significant decrease in ICAM expression and IL-8 release. These findings suggest that ROC exerts anti-inflammatory effects probably through the suppression of COX-2 and iNOS expression.

Antihypertensive Properties of Angiotensin-Converting Enzyme Inhibitors (ACEI) Independent of the Renin-Angiotensin System

Angiotensin converting enzyme inhibitors (ACEi) lead to inhibition of angiotensin II formation and bradykinin inactivation. However, ACEi also have antihypertensive activity that is independent of the renin-angiotensin system. For example, the enhanced peripheral resistance due to smooth muscle cell hypertrophy and hyperplasia (related to lower apoptosis) increases vascular tonus in established hypertension. ACEi treatment restores susceptibility to apoptosis in these cells through stimulation of the Bax protein. Also, an altered function of the Na+/K+ ATPase leads to elevated levels of intracellular sodium concentration, and depolarization of smooth muscle membranes increasing their excitability. ACEi treatment normalizes this pump function, and the arterial tonus by release of endothelial nitric oxide and prostacyclin. Endothelium- dependent hyperpolarization (to acetylcholine) in mesenteric arteries mediated by release of the endotheliumderived hyperpolarizing factor, is impaired in hypertensive humans and animals. In this instance, ACEi restored this impaired response, since this treatment causes vascular remodeling in resistance SHR arteries through induction of apoptosis of vascular smooth muscle cells reducing the subendothelial thickening, which improves the EDHF circulation. The purpose of this review is to analyze the performance of ACEi in normalizing the vascular tonus during the hypertensive state, which may render new perspectives in basic and clinical research for the next years.

Effects of rat/mouse hemokinin-1, human hemokinin-1 and human hemokinin-1(4-11), mammalian tachykinin peptides, on rate and perfusion pressure in the isolated guinea pig heart

Rat/mouse hemokinin-1 (r/m HK-1), human hemokinin-1 (h HK-1) and human hemokinin-1(4-11) (h HK-1(4-11)) are members of the tachykinin family. In the present study, the coronary vascular activities and cardiac functions of r/m HK-1, h HK-1 and h HK-1(4-11) were investigated in isolated, spontaneously beating guinea pig hearts. Bolus injections of r/m HK-1 caused decrease in perfusion pressure indicative of coronary vasodilation, which was primarily due to the action on tachykinin NK1 receptors on vascular endothelial cells, causing the release of nitric oxide that relaxed the coronary vessels. H HK-1 caused biphasic perfusion pressure changes that were coronary vasodilation followed by coronary vasoconstriction. The mechanisms involved in the vasodilation induced by h HK-1 were similar to that of r/m HK-1 while the mechanisms for coronary vasoconstriction were mediated through the activation of tachykinin NK2 receptors on coronary sympathetic neurons to release catecholamines. H HK-1(4-11) only produced coronary vasoconstriction and the mechanisms involved in this effect were similar to that of h HK-1 in vasoconstriction. Moreover, r/m HK-1 and h HK-1 produced similar decreases in heart rate indicative of negative chronotropic responses and the decreases were mainly mediated through the activation of tachykinin NK1 receptors to release ACh acting on muscarinic receptors. H HK-1(4-11) also produced negative chronotropic response, which was mainly mediated through tachykinin NK2 receptors and muscarinic receptors. Our present results provide evidence that all of the three tachykinins could influence cardiac function and coronary vascular activity in the isolated guinea pig heart.