Pharmacological comparison of isolated human cerebral and digital arteries.

Some basic pharmacological differences between isolated human cerebral and digital arteries obtained at postmortem have been studied. Spiral strip responses were measured isometrically and cumulative drug dose-response curves obtained. Contractile responses were sought to norepinephrine, 5hydroxytryptamine, angiotensin, histamine, KCI, BaCl2 and prostaglandin F2o. Relaxation responses (either by the agonists on their own, or in the presence of a resting tonus induced by KCI or 5-hydroxytryptamine) were sought to isoproterenol, histamine, acetylcholine and dopamine. There were no differences between the cerebral or digital arteries in the non-specific responses to KCI or BaClj. Nor were there any differences in the responses to prostaglandin F2Q, or in the receptor mediated responses to 5-hydroxytryptamine or angiotensin. This was in marked contrast to the responses produced by norepinephrine where the maximum response was much larger in digital arteries than in cerebral arteries, although there were no differences in the sensitivity of the 2 vessels to norepinephrine (as measured by the ED60 values). Relaxation responses were difficult to elicit and very variable with only occasional preparations showing relaxation to any of the agonists. These results suggest that the only major pharmacological difference between human digital and cerebral vessels is the number, rather than the sensitivity, of the noradrenergic a-receptors. Stroke Vol 10, No 6, 1979