Expression and pharmacological characterization of α 1-adrenoceptors in rat seminal vesicle

Abstract

In the present study, we investigated the α 1-adrenoceptor subtypes mediating adrenaline-induced contractions of the rat seminal vesicle by using functional studies. The reverse transcription combined with polymerase chain reaction (RT-PCR) was also used to identify of α 1-adrenoceptor mRNA subtypes. The rank order of potency of α 1-adrenoceptor antagonists in blocking the contractile effects of adrenaline was: prazosin=WB 4101⋙BMY 7378>chloroethylclonidine, indicating the presence of α 1A-adrenoceptors in the rat seminal vesicle. In the presence of nifedipine, there was a 76% reduction in the adrenaline-induced contractions. The nifedipine-insensitive component (24%) of the contractile response to adrenaline was unaffected by chloroethylclonidine. A small pool of spare α 1-adrenoceptors for adrenaline (0.10%) was also detected. All three α 1-adrenoceptor subtypes were amplified when RT-PCR was performed on total RNA isolated from rat seminal vesicle. In conclusion, these data indicate the presence of three α 1-adrenoceptor mRNA subtypes, but only α 1A-adrenoceptors are involved in the rat seminal vesicle contraction.