<P> Renin is secreted from juxtaglomerular kidney cells, which sense changes in renal perfusion pressure, via stretch receptors in the vascular walls . The juxtaglomerular cells are also stimulated to release renin by signaling from the macula densa . The macula densa senses changes in sodium delivery to the distal tubule, and responds to a drop in tubular sodium load by stimulating renin release in the juxtaglomerular cells . Together, the macula densa and juxtaglomerular cells comprise the juxtaglomerular complex . </P> <P> Renin secretion is also stimulated by sympathetic nervous stimulation, mainly through beta - 2 adrenergic receptor (β adrenoreceptor) activation . </P> <P> Renin can bind to ATP6AP2, which results in a fourfold increase in the conversion of angiotensinogen to angiotensin I over that shown by soluble renin . In addition, renin binding results in phosphorylation of serine and tyrosine residues of ATP6AP2 . </P> <P> The level of renin mRNA appears to be modulated by the binding of HADHB, HuR and CP1 to a regulatory region in the 3' UTR . </P>

Renin is released in response to all of the following except