PURINERGIC SUPERSENSITIVITY FOLLOWING SYMPATHECTOMY ADDS FURTHER SUPPORT TO CO-TRANSMISSION IN THE RAT VAS-DEFERENS
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1988
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Abstract
Adrenergic and purinergic compounds contract the longitudinal muscles of the rat vas deferens. Whereas ATP and related purinergic analogs produced contractions of greater magnitude in the prostatic half as compared to that of the epididymal end, the magnitude of the .alpha.1-adrenoceptor-induced responses was larger in the epididymal than in the prostatic half of the rat ductus. Chemical sympathectomy following a 48 hr 6-hydroxydopamine-treatment (6-OHDA) caused a leftward displacement of the concentration-response curves for adrenergic and purinergic drugs, this effect being more evident in the prostatic segment. Sympathectomy caused a significant increase in the maximal response induced by ATP and adrenergic compounds which was more evident in the prostatic half of the rat ductus. The denervation-induced supersensitivity was stimulus-specific since angiotensin II and acetylcholine showed no significant change in potency. In the case of bradykinin, there ws a manifest increase in the maximal response of the prostatic segment of the ductus of the chemically denervated tisses. In addition, denervation also caused an increase in the potency of prazosin and phentolamine as .alpha.1-adrenoceptor blocking agents; denervation did not change the potency of yohimbine as an .alpha.2-adrenoceptor blocker.