AJP - Heart and Circulatory Physiology, Vol 234, Issue 3 300-H304, Copyright © 1978 by American Physiological Society
Potentiation of the cerebrovascular response to intra-arterial 5-hydroxytryptamine
B. H. Eidelman, A. D. Mendelow, T. A. McCalden and D. S. Bloom
Infusion of 5-hydroxytryptamine (5HT) into the internal carotid artery of
normal baboons was not accompanied by alteration of gray matter cerebral
blood flow. In animals pretreated with depot estrogen and progesterone
(dosage equivalent to oral contraceptive preparations), infusion of 5HT
produced a marked decrease in gray matter blood flow. A similar decrease in
flow was obtained when the 5HT was infused with a concentrate of
beta-lipoprotein. Steroid substances appear to enhance the cerebrovascular
constrictor responses to 5HT. A further series of six experiments has shown
that the monoamine oxidase inhibitor tranylcypromine similarly produced
constrictor responses to 5HT. It is possible that the steroids, the
beta-lipoprotein, and the tranylcypromine produced constrictor responses to
5HT by the same mechanism (inhibition of cerebrovascular monoamine
oxidase).
