Effect of the gadolinium ion on body fluid regulation
Nozaki, P. N.
Menani, J. V.
De Luca, L. A.
Is part ofPharmacology Biochemistry and Behavior
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Both osmoreception and baroreception are thought to involve ion channels that are sensitive to changes in membrane stretch. We investigated the effect of a blocker of stretch-activated ion channels, the Gd3+ ion, on osmoregulatory and cardiovascular responses in the intact rat. Intracerebroventricular injection of 50-100 nmol Gd3+ reduced thirst induced by various treatments. Similar doses also reduced intake of saline induced by various treatments. Intracerebroventricular injection of 100 nmol Gd3+ transiently increased arterial pressure and reduced the pressor response to intracerebroventricular angiotensin II (Ang II). Systemic administration of Gd3+ failed to alter thirst, except for a high dose (270 mumol/kg) that induced illness. This high dose failed to prevent urinary hypertonicity and excretion of a load of hypertonic NaCl. Intravenous infusion of 270 mumol/kg of Gd3+ reduced blood pressure and pressure responses to intravenous phenylephrine, but did not reduce the baroreceptor reflex control of heart rate. We conclude that the effects of Gd3+ on thirst and on the cardiovascular system are probably not due to a direct effect of the drug on stretch-sensitive ion channels. Instead, many of the effects of Gd3+ were compatible with blockade of voltage-gated Ca2+ channels. (C) 2003 Elsevier Inc. All rights reserved.
CitationPharmacology Biochemistry and Behavior. Oxford: Pergamon-Elsevier B.V., v. 76, n. 2, p. 275-283, 2003.
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