Adrenergic and purinergic components in bisected vas deferens from spontaneously hypertensive rats

Purinergic and adrenergic components of the contractile response to electrical field stimulation (EFS) have been investigated in epididymal and prostatic portions of Wystar Kyoto (WKY) and spontaneously hypertensive rat (SHR) vas deferens. In both halves of SHR and WKY vas deferens, EFS (40 V, 0.5 ms for 30 s, 0.5–32 Hz) evoked frequency‐related contractions. The neurogenic responses were biphasic, consisting of a rapid non‐adrenergic response, dominant in the prostatic portion, followed by a slow tonic adrenergic component, dominant in the epididymal half. Phasic and tonic components of the frequency‐response curves evoked by EFS were significantly higher in the epididymal but not in the prostatic portion of vas deferens from SHR compared to WKY rats. The α 1 ‐adrenoceptor antagonist prazosin (0.1 μ M ) was more effective against both components of the contractile response in the epididymal end of SHR than in WKY rats. Inhibition by α,β‐methylene adenosine 5′‐triphosphate (α,β‐meATP 3 and 30 μ M ) was higher in both components of the contractile responses in WKY preparations than in SHR. Combined α 1 ‐adrenoceptor and P 2x ‐purinoceptor antagonism virtually abolished the EFS‐evoked contractile response in both strains. The degree of inhibition by prazosin (0.1 μ M ) after P 2x ‐purinoceptor blockade was higher in SHR than in WKY rats. These results demonstrate a modification in the purinergic and noradrenergic contribution to neurogenic responses in SHR and WKY animals besides a co‐participation of ATP and noradrenaline in both contractile components of the response to EFS.British Journal of Pharmacology (1999) 128 , 873–880; doi: 10.1038/sj.bjp.0702845