Question

Which of the following statements regarding vasopressin are CORRECT? Choose all of the correct answers. Vasopressin induces the exocytosis of aquaporin vesicles to the apical membrane of collecting duct cells. Vasopressin binds to a nuclear receptor and increases the gene expression of aquaporin subunits. Vasopressin binds to a cell surface receptor. Vasopressin acts primarily on the proximal tubule of the nephron in mammals. Vasopressin circulates in plasma bound to a carrier protein.

Answer 1

The following are the correct statement about vasopressin and they includes;

1. Vasopressin is capable of inducing the exocytosis of aquaporin to the apical membrane of collecting duct cells.  

2. Vasopressin is capable of binding to a nuclear receptor and hence ensure an increase in the expression of aquaporin subunits genes

3. Vasopressin is capable of binding to a cell surface receptor.  

Answer 2

The statements 1, 2 and 3 are CORRECT.

Water excretion by the kidneys is regulated by the hormone vasopressin. It increases the amount of solute-free water reabsorbed back into the circulation from the filtrate in the kidney tubules of the nephrons. Vasopressin binds to the nuclear receptors and increases the gene expression of aquaporin subunits. It increases the water permeability of kidney collecting duct by inducing translocation of aquaporin water channels to the plasma membrane. Aquaporins allow water to move down their osmotic gradient and out of the nephron and increase the amount of water re-absorbed from the filtrate into the bloodstream.  It binds to the receptors on the cells of the collecting duct and allows water reabsorption. The functioning of the hormone is mediated by the vasopressin receptors called the tissue specific G protein-coupled receptors.