EFFECTS OF ACUTE AND CHRONIC DENERVATION OF THE HIND LEG OF THE DOG ON THE BLOOD FLOW RESPONSES IN THE VASCULAR BEDS OF SKIN AND MUSCLE TO ADRENERGIC DRUGS, AND TO ADRENERGIC BLOCKADE

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

The blood flow in acutely and chronically denervated cutaneous and muscular vascular beds of the dog's hind leg was recorded during the administration of adrenergic drugs before and again after the administration of graduated increasing doses of adrenergic blocking drugs.

The femoral nerve and all branches of the ischiadicus nerve were severed. Fifteen dogs were studied immediately after sectioning the nerves and 19 dogs three to four weeks after denervation.

The dogs were anesthetized with morphine followed by a solution of Dial, urethane and pentobarbital. The vessels were cannulated and blood flow was recorded by the electromagnetic flowmeter as described by Johnson et al. (1953).

Blood flow responses to 1 microgm. of l-epinephrine, 1 microgm. of l-norepinephrine, and 5 microgm. of phenylephrine were measured in acutely and chronically denervated skin and muscle vascular beds before and after adrenergic blockade. These responses and the required dose of the adrenergic blocking drugs were compared with the results obtained in the normally innervated skin and muscle beds reported by Johnson et al. (1953).

There was considered to be no pharmacologically significant difference in the blood flow responses to adrenergic drugs or to adrenergic blockade in the denervated preparations as compared with the normally innervated ones.

The dose of adrenergic blocking drugs used by Johnson et al. to reverse the epinephrine response in muscles and to block l-norepinephrine and phenylephrine constriction in muscle and to block the constrictor response to all three in skin, was occasionally different from ours but the difference was never greater than ± one graduated dose.

In acutely denervated skin and muscle the vasodilator responses to small doses of Ilidar per se were less than in the normal skin reported by Johnson, and were larger in acute muscle and chronic skin and muscle to larger doses of Ilidar than in the normal, but these differences are not considered to be pharmacologically significant.

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