VARIATIONS OF THE pH OF THE BLOOD AND THE RESPONSE OF THE VASCULAR SYSTEM TO ADRENALIN

Abstract

In the pithed cat, when the artificial respiration is constant, small intravenous injections of adrenalin act with increasing effectiveness provided blood pH is rising. Thyroid secretion plays no part in this reaction nor does adrenalin in repeated small doses sensitize the sympathetic nervous system. The response may be made to vary by altering blood pH; a progressive increase in response is obtained from pH 6.9 to 8.0. The most effective means of varying the pH within this range is to vary the amount of pulmonary ventilation. Two possibilities are suggested for this enhanced action in a more alkaline medium (1) an increased irritability of the myoneural junction as the blood becomes more alkaline; (2) more complete and rapid oxidation of the drug at a high pH.