Effects of age and hypertension on α1‐adrenoceptors in the major source arteries of the rat bladder and penis

Abstract

As aging and hypertension may impact pelvic arterial blood flow resulting in bladder and penile dysfunction, we investigated effects of age and hypertension on α1‐adrenoceptors in the major source arteries of the rat bladder and penis. Using radioligand receptor binding, real‐time RT‐PCR and fluorescent microsphere infusion techniques, we compared 3 and 22‐month‐old male Fischer rats, and male normotensive Wistar‐Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). Twenty‐two‐month‐old rats and SHRs had significantly higher total α1‐adrenoceptor density in the internal iliac artery and lower blood flow to the bladder and penis than 3‐month‐old and WKY rats, respectively. RT‐PCR data showed an age and hypertension related increase in the expression of α1B‐adrenoceptor mRNA in the internal iliac, vesical and internal pudendal arteries and a switch from α1A predominance in 3‐month‐old and WKY rats to α1B>α1A in 22‐month‐old rats and SHRs. These findings suggest that pharmacological blockade of the vascular α1B‐adrenoceptor, which could increase pelvic blood flow, may contribute to the improvement of bladder and penile dysfunction in animal models for aging and hypertension. Supported by KAKENHI 21791511, Grant‐in‐Aid for Young Scientists (B) provided by the Ministry of Education, Culture, Sports, Science and Technology of Japan.