Transmission blockade and stimulation of ganglionic adenylate cyclase by catecholamines

L Quenzer, D Yahn, K Alkadhi and RL Volle

Isolated rat superior cervical ganglia treated with isoproterenol and related drugs show an increase in ganglionic cyclic adenosine 3':5'- monophosphate (cAMP) and a block of transmission. For isoproterenol, the maximum increase in cAMP occurred at 1 X 10(-6) M, a concentration without effect on transmission. Approximately 5 X 10(-4) M isoproterenol was required to reduce the ganglionic compound action potential by 50%. Dopamine, in contrast to isoproterenol, had no effect on the content of cAMP but depressed transmission. The maximum increase in cAMP produced by norepinephrine occurred with 5 X 10(-4) M, a concentration that reduced transmission by approximately 35%. The effects of isoproterenol on adenylate cyclase and transmission were prevented either by practolol (10(-4) M) or phentolamine (10(-5) M). Dopamine-induced blockade of transmission was antagonized by phentolamine (10(-5) M). Whereas the blockade of transmission by norepinephrine was antagonized by practolol (10(-5) M) or phentolamine (10(-5) M), the stimulation of adenylate cyclase by norepinephrine was prevented by practolol (10(-4) M) but not by phentolamine (10(-5) M). These results show that the blockade of transmission and stimulation of adenylate cyclase are unrelated in rat ganglia and that adrenergic receptor classification is ambiguous. The role of adenylate cyclase in ganglia is unclear.

Volume 208, Issue 1, pp. 31-36, 01/01/1979
Copyright © 1979 by American Society for Pharmacology and Experimental Therapeutics

This article has been cited by other articles:

				M Kawatani, M Rutigliano, and W. de Groat Depolarization and muscarinic excitation induced in a sympathetic ganglion by vasoactive intestinal polypeptide Science, August 30, 1985; 229(4716): 879 - 881. [Abstract] [PDF]