Pharmacological effects of Flurazepam and Diazepam on isolated canine arteries.

Publisher Website
Google Scholar
Abstract
The effects of flurazepam and diazepam [antianxiety agents], benzodiazepine derivatives, on contractions (or contractures) induced by Ca2+, K+ or norepinephrine were examined in the isolated canine coronary artery and thoracic aorta. Ca2+-Induced contraction was evoked by cumulative addition of CaCl2 to Ca2+-depleted K+-depolarizing solution; K+: and norepinephrine-induced contractions were evoked by cumulative addition of KCl and norepinephrine, respectively, to the medium. Flurazepam and diazepam (1 .times. 10-5, 3 .times. 10-5 and 1 .times. 10-4 M for coronary artery; 3 .times. 10-5 and 1 .times. 10-4 M for thoracic aorta) shifted the dose-response curves for KCl downwards in a non-competitive manner, and shifted the dose-response curves for CaCl2 to the right in a competitive manner. Ca2+-Induced contracture was inhibited completely by addition of flurazepam or diazepam (1 .times. 10-4 M), and the inhibition was reversed dose-dependently by addition of CaCl2. Flurazepam and diazepam (3 .times. 10-5 and 1 .times. 10-4 M) shifted the dose-response curves for norepinephrine both rightwards and downwards in the thoracic aorta. Evidently, flurazepam and diazepam inhibit Ca2+-influx into the cells (Ca2+-antagonistic effect), causing relaxation and inhibition of K+-, Ca2+- or norepinephrine-induced contraction (or contracture) of the vascular smooth muscle.