A Novel Pathway Underlying the Inhibitory Effects of Melatonin on Isolated Rat Urinary Bladder Contraction

The aim of the present study was to elucidate the direct effects of melatonin on bladder activity and to determine the mechanisms responsible for the detrusor activity of melatonin in the isolated rat bladder. We evaluated the effects of melatonin on the contractions induced by phenylephrine (PE), acetylcholine (ACh), bethanechol (BCh), KCl, and electrical field stimulation (EFS) in 20 detrusor smooth muscle samples from Sprague-Dawley rats. To determine the mechanisms underlying the inhibitory responses to melatonin, melatonin-pretreated muscle strips were exposed to a calcium channel antagonist (verapamil), three potassium channel blockers [tetraethyl ammonium (TEA), 4-aminopyridine (4-AP), and glibenclamide], a direct voltage-dependent calcium channel opener (Bay K 8644), and a specific calcium/calmodulin-dependent kinase II (CaMKII) inhibitor (KN-93). Melatonin pretreatment (10(-8)~10(-6) M) decreased the contractile responses induced by PE (10(-9)~10(-4) M) and Ach (10(-9)~10(-4) M) in a dose-dependent manner. Melatonin (10(-7) M) also blocked contraction induced by high KCl ([KCl]ECF; 35 mM, 70 mM, 105 mM, and 140 mM) and EFS. Melatonin (10(-7) M) potentiated the relaxation response of the strips by verapamil, but other potassium channel blockers did not change melatonin activity. Melatonin pretreatment significantly decreased contractile responses induced by Bay K 8644 (10(-11)~10(-7) M). KN-93 enhanced melatonin-induced relaxation. The present results suggest that melatonin can inhibit bladder smooth muscle contraction through a voltage-dependent, calcium-antagonistic mechanism and through the inhibition of the calmodulin/CaMKII system.

The expression of resistin-like molecules-a in atherosclerotic plaque / 中华急诊医学杂志

Objective To explore the expression of resistin-like molecules-a (RELMa) in atherosclerotic plaque of ApoE-/- mouse, and to study the effects of RELMa on the proliferation and migration of vascular smooth musclee cells (VSMCs) . Method Nine ApoE-/- mice and nine C57BL/6J mice were fed with high fat diet. All mice were sacrificed 24 weeks after force feeding. Vessels were dissected from to abdominal aorta. Sections of aortic tissue were stained with HE dyeing and RELMa in aortic tissue was assayed by immunohistochemistry. The expression of RELMa mRNA in vessels was detected by RT-PCR. The effects of different concentration RELMa in different concentrations on the proliferation and migration of VSMCs were detected. Data was expressed as mean ± standard deviation. ANOVA were used for comparison in SPSS 11.0, and changes were considered as statistically significant if P value was less than 0.05. Results Atherosclerosis plaque formed in aortic root of ApoE-/- mice after they were fed with high fat diet for 24 weeks. RELMa protein and RELMa mRNA were found by immunohistochemistry and RT-PCR in atherosclerotic plaque of ApoE-/- mouse. RELMa protein didn't be found in vessels of control mouse. RELMa promoted the proliferation of VSMCs (RELMa groups: 2811. 21 ± 216. 89,4056. 87 ±220.65,5061.45 ± 335.86, vs. control 1609.58 ± 203.53, P < 0.01). RELMa promoted the migration of VSMCs (RELMa groups: 130.54±12.98,158.39±11.58,203.50± 17.37 vs. control:70.54± 11.92, P<0.01).Conclusions RELMa expresses in atherosclerotic plaque of ApoE-/- mouse. RELMa enhances the proliferation and migration of VSMCs of aorta.

Inhibited effects of progesterone on contraction and cytomembrane Ca~(2+)-activated K~(+)currents in guinea pig colonic smooth muscles / 中国药理学通报

AIM To study the effects of progesterone on contractile activity of smooth muscle stripes and the large conduction Ca 2+ activated K + currents (BK Ca ) of single colonic myocytes in female guinea pig proximal colons METHODS Stripes and single cells were separated acutely from guinea pig proximal colon Contractions of stripes were measured by isonic transducer, and Ca 2+ activated K + currents were recorded with an Axopatch 1D amplifier under conventional whole cell patterns RESULTS 64 8 ?mol?L -1 progesterone produced longitudinal stripes significantly re laxation(0 1792 g?0 0873 g, n =6, P

Distribution of Smooth Muscles in Hemorrhoids

Hemorrhoids are one of the commonest disorders specific to the human. However, the pathogenesis is not well understood so far. Anal submucosa is largely composed of blood vessels, loose connective tissue and smooth muscles, forming muscular network around the venous plexuses. We analyzed the distribution of smooth muscles in the hemorrhoidal tissues. Immunohistochemical stainings for desmin, vimentin, and Factor VIII related antigen were performed using six freshly frozen hemorrhoidal tissues. All of them were diagnosed as external hemorrhoids. Four anal tissues from Miles' operation specimen without hemorrhoids were used as normal controls. In all six cases, venous plexuses were variably dilated and smooth muscle cells were unevenly distributed. In minimally involved areas, there were relatively sufficient amount of perivascular smooth muscles which were arranged in their bundles. In contrast, only single scattered cells or very small amount of smooth muscle bundles were noted around the dilated vascular plexuses in severely affected areas. In two severe hemorrhoidal tissue samples, vascular plexuses were markedly dilated and only single scattered smooth muscle cells were seen. In conclusion, the total amount of smooth muscles in the submucosa of hemorrhoid tissue was reduced than those of the normal controls. The degree of hemorrhoidal dilation was inversely related to the amount of smooth muscles. However, causal relation between diminution of submucosal smooth muscles and venous dilation remains to be clarified.

Effects of Yiangxuefukang Granules on The Contractility of Uterine Smooth Muscles / 中成药

Objective: To observe effects of Yiangxuefukang Granules on the contractile function of uterine smooth muscles. Methods: Both the uteri of Sprague Dawley rats within 4～6 days postpartum and the uteri isolated from women of caesarean operation were used to study the effects of Yiangxuefukang Granules on the contractile amplitude, frequency and vitality of uterine smooth muscles. Results: The Granules significantly increased the contractile amplitude, frequency and vitality of both rat uterine smooth muscless in vivo and human uterine strips isolated.Conclusion: The Granules can be used in the treatment of the postpartum hemorrhage and the poor uterine involution caused mainly by lacking in the strength of uterine contraction.

Comparative mRNA expressions of Kir2.1 and Kir3.1 potassium channels in rat smooth muscle tissues / 中国药理学通报

left ventricle=cerebral cortex =urinary bladder smooth muscle. CONCLUSION mRNA expression levels of Kir2 1 and Kir3 1 in different tissues were different, this different expressions have physiological significance.