MODULATION OF CYCLIC AMP LEVELS IN THE BOVINE SUPERIOR CERVICAL GANGLION BY PROSTAGLANDIN E, AND DOPAMINE |
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Authors: | V Tomasi Carla Biondi A Trevisani Marta Martini V Perri |
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Institution: | Institute of General Physiology, University of Ferrara, 44100 Ferrara, Italy |
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Abstract: | Abstract— Dopamine, norepinephrine, carbamylcholine and PGE1 (prostaglandin E1). increased cyclic AMP concentrations in slices of bovine superior cervical ganglia. PGF1α was less effective and neither PGE2 nor PGF2α had any effect. Dopamine and PGE, alone or in combination, did not modify low K m cyclic AMP phosphodiesterase activity. Combinations of dopamine and PGE, showed a marked synergistic effect, increasing ganglionic cyclic AMP to a much greater extent than that observed when the two compounds were tested alone. Norepinephrine (10 μ M) , which increased cyclic AMP as much as 10 μ m -dopamine, showed no synergistic effect when tested in the presence of PGE1 or other PGs. Phentolamine, fluphenazine and triflupromazine blocked the dopamine effect without suppressing its synergism with PGE1 Adenylate cyclase of synaptosomes isolated from the ganglia under a variety of experimental conditions appeared to be as responsive to PGE1 as the slices, but it was poorly stimulated by dopamine and was not synergistically modulated by dopamine in the presence of PGE1 These and other data are interpreted as indicating the presence of both a PGE1-sensitive and a PGE1-modulated dopamine-sensitive adenylate cyclase in the cervical ganglion. These adenylate cyclases are tentatively assigned to pre- and post-synaptic structures respectively. |
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