Prejunctional actions of some β‐adrenoceptor antagonists in the vas deferens preparation of the guinea‐pig

Open Access
Publisher Website
Google Scholar
Abstract
1 . The β-adrenoceptor antagonists propranolol, pronethalol, MJ 1999 and Ciba 39089-Ba reduced responses to field stimulation of the guinea-pig isolated vas deferens preparation without significantly affecting responses to exogenously added noradrenaline. 2 . This prejunctional blocking action of the drugs cannot be correlated with their action as β-adrenoceptor antagonists or non-specific depressants. 3 . The blockade produced was more pronounced at low (520 Hz) than at high (50 Hz) frequencies of stimulation. 4 . The blockade was slow in onset, and once established was poorly reversed by washing the preparation over a period of 1 to 2 h. 5 . The blockade produced could be reversed by dexamphetamine and cocaine. 6 . These experiments suggest that the β-adrenoceptor antagonists may have some actions which closely resemble those of the adrenergic neurone blocking agent guanethidine.