Question

What is the mechanism of action of vasopressin?

A.) insertion of AQP-2 into the apical membrane of distal tubule cells
B.) opening of AQP-2 channels in the basolateral surface of proximal tubule cells
C.) closure of V2 receptor channels, preventing sodium movement and osmosis of water from the tubule to the interstitial pace.
D.) decreasing the resistance in the afferent arteriole

Answer 1

ADH, or vasopressin, causes the insertion of aquaporin channels into the apical membrane of principal cells in the collecting ducts of the kidney, allowing water reabsorption and leading to concentrated urine. ADH also constricts arterioles in peripheral circulation.

Step-by-step explanation:

ADH, or vasopressin, causes the insertion of aquaporin channels into the apical membrane of principal cells in the collecting ducts of the kidney. This allows water to be pulled osmotically from the collecting duct into the surrounding interstitial space and then into the peritubular capillaries. As a result, the final urine becomes more concentrated. When less ADH is secreted, fewer aquaporin channels are inserted, and less water is recovered, leading to dilute urine.

ADH also has effects on blood vessels by constricting the arterioles, which reduces blood flow to the extremities and increases blood supply to the core of the body. However, this is not directly related to the mechanism of action of vasopressin in the kidney.