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Br J Clin Pharmacol. 1997 Dec;44(6):569-71.

Dose- and time-dependency of the dilator effects of the endothelin antagonist, BQ-123, in the human forearm.

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Department of Medicine, Cantabria University of Spain, Santander.



Endothelin-1 is a potent endogenous vasoconstrictor that acts on the endothelin A (ET[A]) receptor. The dose-response and time-course of the dilator effect of the ET(A) receptor antagonist, BQ-123, was investigated in the forearm of healthy volunteers.


Forearm blood flow was measured using mercury-in rubber strain gauge venous occlusion plethysmography.


Following intra-arterial infusion of BQ-123 (50 nmol min-1) for 5 min, forearm blood flow increased by approximately 60% over the next 60 minutes; lower doses were without significant effect. The degree of dilatation was similar to that observed in previous studies using 20-fold larger doses.


This study confirms that basal endothelin-1 has a role in the physiological regulation of vascular tone. It is possible that at low doses, BQ-123 might be a more sensitive pharmacological tool for the detection of abnormal endothelin-1 mediated constriction.

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