MECHANICAL AND METABOLIC EFFECTS OF BETA-RECEPTOR STIMULATORS, C-TERMINAL OCTAPEPTIDE OF CHOLECYSTOKININ, AND PROSTAGLANDIN-E-2 ON ISOLATED, DEPOLARIZED SPHINCTER OF ODDI

Similar to their actions on normally polarized, isolated sphincter of Oddi, the .beta.-receptor stimulators isoprenaline and terbutaline, and prostagladin E2 produced relaxation of the depolarized preparation. The relaxation was accompanied by an increase in intracellular cyclic [c] AMP. In contrast to its relaxing effect on normally polarized sphincter preparations, the C-terminal octapeptide of cholecystokinin (C8-CCK) contracted or had no effect on the depolarized sphincter. There was no change or a small decrease in the content of cAMP in the muscle. The relaxing effects of .beta.-receptor stimulators and prostaglandin E2 on isolated sphincter of Oddi, and the simultaneous increase in cAMP-content are mediated by processes independent of the electrical activity of the membrane. C8-CCK mediated relaxation and increase in cAMP is dependent on the membrane potential.