EVIDENCE THAT THE PrPURINOCEPTOR IN THE MOUSE ISOLATED VAS DEFERENS IS AN ArSUBTYPE

Abstract

The effects of adenosine,5-N-ethylcarbox-amidoadenosine (NECA), 2-chloroadenosine (2-CA), N6-phenyiisopropyladenos'tne (L-PIA and D-PIA) and N6 -cyclohexyladenos'tne (CHA) were examined on the mouse Isolated vas deferens. All the compounds in a concentration-dependent manner inhibited electrically induced contrac¬tions. IC of adenosine and its analogues were 13.68 ± 5.97 for Ado, 0.736 ± 0.087 for 2-CA, 0.034 ± 0.009 for CHA, 0.056 ± 0.008 for L-PIA, 0.099 ± 0.028 for NECA, and 1.444 ± 0.183 for D-PLA. The P, -purinoceptor antagonist, 8-PT , caused a rightward shift of all the adenosine and its analogues concentration-response curve. Dipyri¬damole, an adenosine uptake inhibitor potentiated the relaxation to adenosine thus causing a leftward shift of adenosine concentration-response curve. Dipyridamole had no effect on the relaxation induced by the analogues. The order of the potency for the adenosine and its analogues on the mouse isolated vas deferens was: CHA> L-PIA> NECA> 2-CA> D-PIA> Ado. This study proposes that adenosine and its analogues mediate their inhibitory effects on the mouse isolated vas deferens via At adenosine receptors.