Multiplicative interaction between angiotensin II and K concentration in stimulation of aldosterone

The interaction of angiotensin II and plasma K concentration in stimulating aldosterone secretion was studied in a group of six dogs by determining the aldosterone response to three levels of angiotensin II while the dogs were maintained on three levels of K intake. The levels of angiotensin were 1) the endogenous level, 2) the concentration resulting from infusion of 5 ng X kg-1 X min-1, and 3) the concentration resulting from infusion of 10 ng X kg-1 X min-1. Each level was maintained for 5 days. The three rates of K intake were 10, 100, and 200 meq/day, each maintained for 3 wk. Data were analyzed from days 1, 2, and 5 of the angiotensin infusion periods. The regressions obtained from plotting plasma K (PK) versus aldosterone concentration on day 5 of each level of infusion were 1) for no infusion (endogenous PRA = 0.4 to 0.5 ng ANG I X ml-1 X h-1), aldosterone = 5.04 X PK - 16.56; 2) for 5 ng X kg-1 X min-1 infusion, aldosterone = 12.20 X PK - 39.09; and 3) for 10 ng X kg-1 X min-1 infusion, aldosterone = 35.50 X Pk - 119.31. Each regression was significantly different (P less than 0.001) from the other two. The plasma K axis intercepts, which are the points at which aldosterone secretion is zero, were 3.29, 3.20, and 3.36 for the regression from the 0, 5, and 10 ng X kg-1 X min-1 infusion rates, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)