Fig. 3.

Effects of addition of different stimulators on renin secretion rates of isolated mouse kidneys perfused at a constant pressure of 90 mmHg. Data were obtained after a stable plateau phase had been reached. Isoproterenol at 10 nM, which activates AC isoforms leading to increased cAMP levels, elicited a similar stimulation of renin secretion as 250 µM 8-bromo-cAMP, a degradation-resistant cAMP analog (§). EGTA (3.1 mM) further enhanced renin secretion to a similar extent in the presence of both 10 nM isoproterenol and 250 µM 8-bromo-cAMP, indicating mechanisms of action not related to modulation of intracellular cAMP levels (*P < 0.05; data are means ± SE of 4 kidneys).