Effect of adrenalectomy and cortisone on peripheral nerve function

¹ Department of Physiology, College of Medicine, University of Florida, Gainesville, Florida

Fifty-four male Holtzman strain rats, 200–250 gm, were subjected to the same surgical treatment; 27 adrenalectomized, the others sham-operated. Fifteen of each group were kept on normal diet; four on 0.9% NaCl drinking water; four given daily injections of 1 mg cortone acetate and four, 2 mg cortone acetate. The excitability constant k (H. A. Blair. J. Gen. Physiol. 15: 709, 1932) was 30% lower in adrenalectomized rat nerve than in normal and the velocity of conduction was slightly decreased. The effect of adrenalectomy on excitability and conduction was reversed or prevented by 1 mg cortone acetate or by 0.9% NaCl drinking water. Two milligrams cortone acetate in normal animals also reduced k slightly but did not affect the velocity. The survival time of adrenalectomized rat nerve deprived of oxygen was decreased 12% from normal. Administration of cortisone to normal animals also resulted in a slightly decreased survival time. The oxygen uptake rate was 214 cu mm/gm/hr. in nerves from adrenalectomized rats; 181 cu mm/gm/hr. in normal rat nerves, an increase of 18%. Immersion of normal rat nerves in low-sodium solution (less than 10% of normal) produced excitability changes similar to the adrenalectomy effects. It is concluded that the effect of adrenalectomy on excitability of peripheral nerve is due to the resultant change in electrolyte balance, especially with respect to the Na ion and an apparent contradiction between results obtained from brain tissue and nerve tissue by previous investigators has been resolved.