Figure 1.

The renin-angiotensin-aldosterone activation cascade. Several stimuli including a decrease in blood pressure (BP), reduced sodium (Na⁺) levels, or activation of the autonomic nervous system promote the conversion of pro-renin into renin, which then cleaves angiotensinogen into angiotensin I. Subsequently, angiotensin I is converted into angiotensin II and binds to angiotensin receptors in brain, heart, kidney, adrenal cortex and arterioles to retain water, reabsorb sodium and initiate vasoconstriction. (ACE = angiotensin-converting enzyme; ADH = antidiuretic hormone; Ang = angiotensin; AT1R = angiotensin receptor type 1; ECF = extracellular fluid; K⁺ = potassium; Na⁺ = sodium; PVR = peripheral vascular resistance; β-AR = β-adrenergic receptor activation).