Cerebrovascular response to intracarotid infusion of 5-hydroxytryptophan and L-DOPA in cats.

Intracarotid administration of 5-hydroxytryptophan (10 mg/kg) results in a slight vasoconstriction of cerebral vessels. L-DOPA (20 mg/kg) administered by the same route enhances cerebral blood flow. The effect on cerebral blood flow of L-DOPA (20 mg/kg) following intracarotid 5-hydroxytryptophan (10 mg/kg) administration shows a potentiation of cerebral blood flow response in non-pretreated as well as in nialamide- and reserpine-pretreated cats.