Short Term Effects of Hypercholesterolemia on Corpus Cavernosal Tissue in Rabbits

Kwak, Kyoung Min; Seo, Seong Il; Hwang, Tae Kon

Abstract

PURPOSE: To study the short term effects of hypercholesterolemia on corpus cavernosal tissue, we performed isometric tension studies and RT-PCR was used to identify mRNA expression of VEGF on isolated strips of corpus cavernosum, on rabbits which underwent partial ligation of the abdominal aorta and received a diet containing 2% cholesterol.
MATERIALS AND METHODS
New Zealand White rabbits were divided into a control group(n=6) fed with a regular diet and a hypercholesterolemic group(n=10) which underwent partial ligation of the abdominal aorta and received a diet containing 2% cholesterol. After 3 weeks, the relationship between hypercholesterolemia and cavernosal smooth muscle pathophysiology was studied. To characterize the cavernosal smooth muscle reactivity in hypercholesterolemia, we performed isometric tension studies with phenylephrine(PE), acetylcholine(Ach), sodium nitroprusside(SNP) and electrical field stimulation(ES). RT-PCR was used to identify the mRNA expression of VEGF.
RESULTS
PE-induced cavernous smooth muscle contraction in the hypercholesterolemic group was increased compared with the control group(p<0.05), while relaxation by Ach and ES in PE pretreated cavernosal smooth muscle in the hypercholesterolemic group was decreased(p<0.05). Relaxation by SNP in PE pretreated cavernosal smooth muscle was not different between any experimental groups. Expression of VEGF mRNA in cavernosal smooth muscle was significantly increased in the hypercholesterolemic group compared with the control group.
CONCLUSIONS
Hypercholesterolemia caused a significant increase in PE-induced contraction of cavernosal tissue. Hypercholesterolemic cavernosal tissue retained the ability of relaxation induced by endothelium-independent, but relaxation induced by endothelium-dependant was impaired. Furthermore, expression of VEGF mRNA in cavernosal tissues was up regulated in the hypercholesterolemic group. This study showed that a short period of hypercholesterolemia could induce pathophysiologic change of cavernosal tissue.