Central hypotensive effects of imidazole acetic acid and rolipram (ZK 62 711) in rats
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In urethane-anaesthetized rats the administration of imidazole acetic acid (IAA), 34–272 μg per rat intracerebroventricularly (i.c.v.), induced a dose-related fall in blood pressure. Rolipram (ZK 62 711), a potent and selective inhibitor of cyclic AMP phosphodiesterase (cAMP-PDE), also lowered the blood pressure in a dose-dependent manner when administered at the doses of 1–64 μg per rat i.c.v. A subhypotensive dose of rolipram (0.25 μg per rat i.c.v.) did not change the hypotensive effect of IAA. Pretreatment of the rats with metiamide, 1.1. mg per rat i.c.v., shifted the dose-response curve for IAA significantly to the right. The present results make it unlikely that the central hypotensive effect of IAA could be due to the stimulation of cAMP-PDE by this agent. Central histamine H2-receptors may be involved in the hypotensive effect of IAA.
KeywordsAcetic Blood Pressure Acetic Acid Histamine Imidazole
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