FUNCTIONAL-RESPONSES OF THE RAT ISOLATED SEMINAL-VESICLE TO ELECTRICAL-FIELD STIMULATION - A PHARMACOLOGICAL ANALYSIS

1. Electrical field stimulation (EFS) of the rat isolated seminal vesi cle elicited frequency-dependent and tetrodotoxin sensitive contractio ns which were unaltered by hexamethonium or mecamylamine. 2. Prazosin alone was not sufficient to abolish these responses, but a combination of atropine and prazosin was fully effective, indicating involvement of both noradrenergic and cholinergic mechanisms. 3. Responses were pr edominantly cholinergic (blocked by atropine, potentiated by ecothiopa te but not significantly altered by prazosin or guanethidine) at 1-8 H z but became increasingly noradrenergic (blocked by prazosin or guanet hidine but relatively unaltered by atropine or ecothiopate) with incre asing frequencies of stimulation. 4. Electrical field stimulation of s eminal vesicles removed from reserpine or 6-hydroxydopamine (6-OHDA)-p retreated rats produced contractions that were clearly cholinergic in nature. 5. After exposing the seminal vesicles to guanethidine, or aft er pretreatment of rats with 6-OHDA, responses to EFS remained, indica ting that activation of discrete cholinergic and noradrenergic innerva tions seem to underlie the contractile responses observed. 6. Yohimbin e and prazosin potentiated the predominantly cholinergic responses at 1, 2 and 4 Hz in tissues from untreated rats, but not in those from an imals pretreated with reserpine or 6-OHDA, indicating the possibility of an interaction between the two innervations. 7. No inhibitory respo nses to EFS could be demonstrated in tissues precontracted with KCl in the presence of a combination of atropine and prazosin suggesting the absence of a nonadrenergic, noncholinergic inhibitory innervation.