Renin secretion is controlled by at least 4 mechanisms, which are not mutually exclusive: A renal vascular receptor responds to changes in tension in the afferent arteriolar wall A macula densa receptor detects changes in the delivery rate or concentration of sodium chloride in the distal tubule Circulating angiotensin has a negative feedback effect on renin secretion Sympathetic nervous system stimulates renin secretion mediated by beta-receptors (via the renal nerve) Angiotensin is generally acknowledged to be responsible for renovascular hypertension, at least in the early phase, but the role of the renin-angiotensin-aldosterone system in primary hypertension is not established.