Effects of prostaglandin E2 on fast and slow components of the response of the rat vas deferens to field stimulation

1 The response of the rat vas deferens to field stimulation with single pulses is biphasic. The first, rapid component of the response is dominant at the prostatic end and is thought by some to be mediated by non‐adrenergic, non‐cholinergic neurotransmission. The second, slower component predominates at the epididymal end and has the usual properties associated with adrenergic responses. 2 Prostaglandin E2 (PGE2, 10−8 to 10−5 mol/l) inhibited the ‘fast component’ responses elicited by field stimulation of the prostatic vas from reserpine‐treated rats. The prostaglandin was more potent in the presence of 1.25 than 2.5 mmol/l Ca2+. 3 PGE2 (10−7 to 10−5 mol/l) had similar effects on prostatic preparations from normal rats, but was less active on these. 4 PGE2 (10−9 to 10−5 mol/l) did not inhibit the ‘slow component’ responses resulting from field stimulation of the epididymal vas but rather, at the two highest concentrations used (5 × 10−6 and 10−5 mol/l), potentiated them. These high concentrations of the prostaglandin also potentiated the contractions of the epididymal vas elicited by exogenous noradrenaline. 5 These effects of PGE2 on the two components of the response of the rat vas deferens are not as might be expected from its inhibitory effects on the ‘typical’ adrenergic neurotransmission in several other sympathetically‐innervated tissues.