DILATOR RESPONSES TO ISOPROTERENOL IN CUTANEOUS AND SKELETAL MUSCLE VASCULAR BEDS; EFFECTS OF ADRENERGIC BLOCKING DRUGS

¹ Department of Physiology and Pharmacology, Bowman Gray School of Medicine of Wake Forest College, Winston-Salem, N. C.

By means of the electromagnetic flowmeter, the vasomotor responses to intra-arterial injections of isoproterenol were compared to those of epinephrine and levarterenol in cutaneous and skeletal muscle vascular beds before and during blockade with azapetine (Ilidar) and phenoxybenzamine (Dibenzyline).

Isoproterenol caused vasodilation in both beds.

In skin, the dilator respotises to isoproterenol were blocked by approximately the same dose as that which blocked the constrictor responses to epinephrine and levarterenol, i.e., 10 mgm./kgm. of phenoxybenzamine and 30 mgm./kgm. of azapetine.

In muscle, the dilator responses to isoproterenol were blocked at the same dose that abolished the dilator responses to epinephrine, i.e., 1 mgm./kgm. of phenoxybenzamine and 60 mgm./kgm. of azapetine. These were approximately 20 times the dose required to block the constrictor responses to levarterenol.

It was suggested that epinephrine behaves as if it were a composite of both levarterenol and isoproterenol.