A COMPARTMENTAL MODEL OF ACUTE STIMULATION OF ALDOSTERONE SECRETION IN-VIVO BY POTASSIUM AND ANG-II

Conscious sheep with an adrenal autotransplant were used to study the relationship between acute change in K+ concentration and acute change in aldosterone secretion rate (ASR). The kinetics of K+ within the adrenal circulation were shown to be consistent with distribution within a single compartment. In contrast, change in ASR during and after KCl infusion was consistent with a two-compartment model, where ASR was a sigmoidal function of concentration of K+ (or other unidentified agent) in the second, or 'effect,'' compartment. Prior work on the relationship between acute change in angiotensin II (ANG II) concentration and acute change in ASR was extended by investigating the interaction of K+ and ANG II in the control of ASR. The results of this study indicate that acute change in ANG II concentration may cause an inhibition of the usual response of the adrenal to acute change in K+ concentration.