Circulatory performance under surgical stress during adrenocortical suppression.

Abstract

In dogs, the oral administration of prednisolone phosphate at 50 mg/day for 14 days did not induce significant adrenocortical suppression as evidenced by a pronounced elevation in plasma free 17-hydroxycorticosteroid (17-OHCS) after surgical trauma. In another group the same drug regimen caused a failure of steroid elevation when a rapid functional ACTH test was performed. A minor degree of adrenocortical inhibition probably occurred. In this circumstance, the difference in adrenocortical responses may have been related to the more prolonged and therefore effective stimulation of the adrenal cortex by surgery. The same dose of prednisolone given for a 28-day period induced failure of any adrenocortical response to surgical stress. Despite a definitely limited adrenocortical reserve, the animals withstood surgery and a 2-day postoperative period with no evidence of circulatory collapse or impairment of the pressor response to levarterenol. The findings pose a question as to the significance of high levels of plasma 17-OHCS normally observed under stress, beyond providing a minimal quantity necessary for homeostasis.