Question

How does nicotine affect the water retention relation of the kidneys?

Answer 1

Nicotine's action at the medulla causes the release of Vasopressin, aka Anti-diuretic Hormone, which causes anti-diuresis by two mechanisms. One, is the increased water permeability at the distal tubules and collecting ducts of the kidney allowing greater reabsorption of water. Two, increased urea permeability of the inner medullary portion of collecting duct.