The effects of intracerebroventricular administration of tonin on water drinking and blood pressure in rats.

Abstract

Intraventricularadministration of tonin, an enzyme which forms angiotensin II directly from a natural protein substrate (angiotensinogen), stimulated water drinking and increased systemic blood pressure in rats. These responses were abolished by the simultaneous administration of an angiotensin II analogue, but unaffected by an angiotensin I-converting enzyme inhibitor. We confirmed, in vitro, that angiotensin II was generated when the brain homogenate was incubated with tonin in the presence of DFP and EDTA. These results indicate that the central effects of tonin on water drinking and systemic blood pressure are mediated via the direct formation of angiotensin II in the brain, and suggest the possibility that the tonin-angiotensin II system in the central nervous system might be important in controlling water balance and blood pressure.

Angiotensin II Type 1 Receptor Blockers Inhibit KAT II Activity in the Brain—Its Possible Clinical Applications

“…Reduction of AT-II synthesis and inhibition of AT 1 R are the main goals of antihypertensive therapy. Since other enzymes, e.g., tonin, may produce AT-II from angiotensin I or angiotensinogen (Kondo et al 1980 ), AT 1 R blockers (ARBs) seem to provide better control over RAS activity than angiotensin converting enzyme (ACE) inhibitors.…”

Metoclopramide Enhances Bethanechol‐induced Pancreatic Exocrine Secretion of the Dog

“…Dopamine is present in the adrenal gland, the brain, peripheral sympathetic nerves and circulation, and probably has a role in blood pressure regulation (Van Loon & Sole 1980;.Hilditch & Drew 1984). Therefore, the antidopaminergic action of metoclopramide (Jenner & Marsden 1979) possibly contributed to the transient increase in blood pressure by antagonizing endogenous dopamine, especially in the central nervous system, as suggested previously (Kondo et al 1981). The initial decrease in blood pressure by large doses of metoclopramide may be attributable to its direct action.…”