The Expression And Correlation Of Intermediate Conductance Calcium-activated Potassium Channels In Cavernous Tissue Of Spontaneously Hypertensive Rats

Background:Erectile dysfunction(ED)is a common complication of hypertension.The prevalence of ED among hypertension men varies from 24% to 32%.ED is two to three times more common in hypertension than in normotensive men.The attention to hypertensive ED has very important practical significance.The mechanism of hypertensive ED is complex and unknown,researchs confirmed that vascular endothelial dysfunction is one of the important reasons.Besides the well-established nitric oxide(NO)/ prostacyclin(PGI2),recent reports have shown the existence of a thirdly,distinct endothelial factor involving the endothelium-dependent hyperpolarization factor(EDHF).The intermediate conductance calcium-activated potassium channels(IKCa)are key players in EDHF-mediated relaxation,impact on hypertensive ED endothelial function is not clear at present? Purpose:The aim was to validate the hypothesis that the effect of hypertension on intermediate conductance calcium-activated potassium channels in cavernous tissue of spontaneously hypertensive rats.Materials and Methods:Male spontaneously hypertensive rats(SHR)(n=30)and normotensive Wistar Kyoto rats(WKY,n=10)were studied,Systolic blood pressure(SBP)was measured by noninvasive blood pressure instrument and erectile function was tested by injecting with apomorphine(APO),the rats were divided into2 groups,namely hypertensive with erectile dysfunction group(n=20)and control group(n=10).The right carotid was exposed by 25 G needle which was filled with heparinized saline punctured the carotid artery and connected the pressure converter,continuous monitoring and recording the mean arterial pressure.along the ventral midline abdominal cavity was opened,,free the prostate leaves and find the cavernous pelvic ganglion as a stimulation spot.25 G needle which was filled with heparinized saline successfully punctured the corpus cavernosum and connected the converter,measuring the intracavernous pressure.Corpus cavernosum specimens were divided into two parts.One part was stored in-80? ultra low temperature freezer preservion,The other part was used for immunohistochemical analysis immediately.The expression of IKCa gene mRNA and protein was assessed by Western blotting ?RT-PCR and immunohistochemistry? Results:Hypertensive erectile dysfunction group(n=20)were screening,WHY group(n=10)rats full erection,erectile rerction rate were 100%.versus the WKY group,SHR group showed a higher systolic blood pressure(202.43±9.89 vs.27.21±3.48mmHg)(P<0.01),and the erectile rerction rate were33%.In 0V electrical stimulatiom.ICP/MAP was significantly decreased in group SHR(0.27±0.01)than the WKY group(0.38±0.02)(P<0.05).In 5V electrical stimulation,ICP/MAP was significantly decreased in group SHR(0.31 ± 0.01)than WKY group(0.76 ±0.01)(P<0.01).Western blotting,real time fluorescence quantitative PCR(rt-pcr)and immunohistochemical display the IKCA protein and mRNA expression in SHR group of corpus cavernosum tissue were significantly lower than the WKY group.Conclusion:Hypertension inhibits expression of IKCa in the cavernous tissue of SHR rats,This could play a key role in the pathophysiology and mechanism of erectile dysfunction in SHR rats.