Fig. 1.

Effects of addition of EGTA (3 mM) to the perfusate on renin secretion (A) and flow (B) of isolated mouse kidneys perfused at a constant pressure of 90 mmHg. After a control period, isoproterenol (10 nM) was added to the perfusate (arrows), which led to a moderate increase of flow and to a fivefold increase of renin secretion. Further addition of EGTA to the perfusate in the presence of isoproterenol led to rapid overshooting increase of renin secretion followed by a plateau of renin secretion that was about fourfold higher than with isoproterenol alone. After removal of EGTA from the perfusate, renin secretion rates rapidly returned to previous values. The temporal changes of renin secretion induced by EGTA were rather similar to the changes of perfusate flow. Data are means ± SE of 4 kidneys.