Time-dependent effects of extraluminally-applied oxyhemoglobin and endothelial removal on vasodilator responses in isolated, perfused canine basilar arteries

Pharmacology
T TsujiD A Cook

Abstract

The effects of oxyhemoglobin (oxyHb) and removal of the endothelium have been measured in isolated, perfused canine basilar arteries treated with intraluminal vasodilator drugs. In preparations with an intact endothelium, acetylcholine (ACh) produces a biphasic response, where a small vasodilation precedes a vasoconstriction. Calcium ionophore A23187 and thimerosal induce a vasodilation at low doses and a biphasic response at high doses. Sodium nitroprusside (SNP) evokes only a vasodilation. Extraluminally applied oxyHb itself produces a transient vasoconstriction and then a gradual increase in perfusion pressure. After this treatment, the vasoconstriction to ACh was enhanced as was the vasodilation to SNP. Significant attenuation of the vasodilator action of A23187 and thimerosal was also observed. Subsequent removal of endothelium produced no further change in response. This implies that the action of extraluminal oxyHb is to eliminate any endothelium-dependent responses. If cerebral vasospasm after subarachnoid hemorrhage is initiated by hemoglobin released from the clot surrounding the artery, at least one component of its action appears to involve interference with endothelial function.

Citations

May 1, 1995·Pharmacology & Therapeutics·D A Cook
Sep 1, 1994·Journal of the Autonomic Nervous System·T TsujiD A Cook
Aug 1, 1998·Journal of Controlled Release : Official Journal of the Controlled Release Society·T KaminumaT Yoshimoto
Jun 1, 1993·Stroke; a Journal of Cerebral Circulation·K TakenakaK S Lee
Aug 1, 1991·Stroke; a Journal of Cerebral Circulation·R L Macdonald, B K Weir
May 30, 2003·Pharmacological Reviews·Noboru Toda, Tomio Okamura
Dec 5, 2003·Acta Neurologica Scandinavica·Jacob Hansen-Schwartz

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