Figure 124

Angiotensin II actions on tubular transport. Angiotensin II receptors are located on both the luminal and basolateral membranes of the proximal and distal nephron segments. The proximal effect has been studied most extensively. Activation of angiotensin II-AT1 receptors leads to increased activities of the sodium-hydrogen (Na+-H+) exchanger and the sodium-bicarbonate (Na+-HCO-3) cotransporter. These increased activities lead to augmented volume reabsorption. Higher angiotensin II concentrations can inhibit the tubular sodium reabsorption rate; however, the main physiologic role of angiotensin II is to enhance the reabsorption rate [28]. cAMP—cyclic AMP; G—G protein; PLA—phospholipase A. (Adapted from Mitchell and Navar [28].)

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