Module 7: Figure renin secretion
Control of renin secretion by renin-producing granular cells.
Renin-producing granular cells are regulated by a large number of signalling systems that all seem to focus on cyclic AMP. Both the Ca2+ and the nitric oxide (NO)/cyclic GMP signalling pathways modulate the level of cyclic AMP. Released renin acts to hydrolyse angiotensinogen to angiotensin I, which is then converted into angiotensin II through angiotensin-converting enzyme (ACE). The angiotensin II is part of a negative-feedback loop, since it acts to increase Ca2+ that inhibits adenylyl cyclase 5 (AC5), thereby reducing the level of cyclic AMP.