Aldosterone exes action on: (A) Proximal tubule, (B) Early Distal tubules, (C) Loop of Henle, (D) Collecting duct
Answer is D. Aldosterone acts on the late DT and CD cells by combining with an intracellular mineralocoicoid receptor - induces the formation of' aldosterone-induced proteins' (AlPs) which promote Na+ reabsorption by a number of mechanisms and K+ secretion. Aldosterone (AL) penetrates the cell from the interstitial side and combines with the mineralocoicoid receptor (MR). The complex translocates to the nucleus-promotes gene mediated mRNA synthesis. The mRNA then directs the synthesis of aldosterone-induced proteins (Alps). The AlPs activates Na+ channel, translocate Na+ channels from cytosolic site to the luminal membrane and Na+K+ATPase of the basolateral membrane, increase ATP production by mitochondria. All these changes promote Na+ reabsorption-more K+vand H+ is secreted indirectly ( Essentials of Medical Pharmacology, K.D Tripathi,6tth edition, page 570 )