Search results for "Phentolamine"
showing 3 items of 23 documents
The determination of presynaptic pA2 values of yohimbine and phentolamine on the perfused rat heart under conditions of negligible autoinhibition
1983
Abstract 1 Rat isolated perfused hearts with the right sympathetic nerves attached were loaded with [3H]-(-)-noradrenaline. The nerves were stimulated with up to 40 trains of 10 pulses every min at 1 Hz, and the evoked increases of [3H-]noradrenaline overflow into the perfusate, of right atrial tension development and ventricular beating frequency were measured. 2 Oxymetazoline inhibited the evoked transmitter overflow (IC50: 10 nM) and decreased the postsynaptic responses in a concentration-dependent manner. It behaved as a full against in abolishing the evoked transmitter overflow. 3 Yohimbine up to 1 microM neither enhanced the evoked [3H]-noradrenaline overflow nor the postsynaptic para…
Actions of alpha-adrenoceptor blocking agents on two types of intracellular calcium stores mobilized by noradrenaline in rat aorta.
1993
In isolated rat aortic strips noradrenaline induces a biphasic contractile response in Ca-free medium, associated with two different intracellular calcium pools, one of which is common to caffeine. We analyzed the mechanisms involved in the depletion and repletion of both intracellular Ca pools sensitive to noradrenaline in different experimental procedures in presence of prazosin, phentolamine and yohimbine. At 37 degrees C the alpha-adrenergic blocking agents inhibited contractile responses to noradrenaline in Ca-free medium, with prazosin being highly selective. alpha 2-adrenoceptors probably do not participate in the release of Ca from internal stores, as no contractile response was obs…
Modifications induced in the renin-angiotensin-aldo-sterone system of rats by alpha-blocking drugs.
1978
Summary The data reported in the present paper refer to quantitative variations of plasma renin activity and plasma aldosterone levels after administration of alpha-blocking agents, i.e. phentolamine, phenoxybenzamine and gihydroergotoxin derivatives, either to rats kept on a standard diet with water ad libitum or to rats receiving distilled water load, the latter treatment causing an increase of both plasma renin activity and plasma aldosterone levels if compared to control values. No strict correlation between (a) drug-induced modifications of plasma renin activity and plasma aldosterone levels and (b) blood pressure drop caused by the same drugs was shown to occur under either experiment…