Pharmacological in vitro analysis of amine-mediated vasomotor functions in the intracranial and extracranial vascular beds.

The cerebrovascular system (the extra- as well as intracerebral vessels) receives a well-developed innervation by the adrenergic (originating in the superior cervical sympathetic ganglia) and cholinergic nerves. In addition, recent immunohistochemical studies have shown the presence of vasodilatory peptidergic nerve fibres. There may be an association of cerebral blood vessels also with various aminergic nerve systems of intracerebral origin. Besides the nerves, amine-containing mast cells are often located in close relation to the brain vessels. The specific receptors mediating the contractile and dilatory response of the various vasoactive amines--noradrenaline, dopamine, 5-hydroxytryptamine, histamine, acetylcholine--have been characterized in detail in pharmacological experiments. There is a number of major differences in the reactivity of cerebral vessels as compared to vasomotor functions in the peripheral circulation. The observations and results provide a basis for a better understanding of physiological neurogenic control mechanisms in the cerebral circulation, and they may also have implications for the interpretation of pathophysiological phenomena related to, for example, migraine and the vasospasm following subarachnoid hemorrhage.