Homeostasis - urinary system and water balance

1)  Urine production would increase. Salt, amino acids, and glucose are actively transported from the nephron in the area of  the proximal tubule. The reduced active transport capabilities, due to the inhibition of ATP formation, would mean a  higher solute concentration (increased osmotic pressure) in the nephron. Because of the higher osmotic pressure in the nephron, less water is reabsorbed, increasing urine production.

2) The reduced blood flow to the kidney would be detected by the juxtaglomerular apparati. Renin would be released, converting angiotensinogen to angiotensin. The angiotensin causes constriction of local arterioles (this increases blood pressure) and initiates the release of aldosterone from the adrenal cortex. Aldosterone, by increasing Na+ transport from the nephrons, increases water reabsorption, which helps elevate blood pressure.

3) No. It could have passed into the nephron via secretion in other regions of the nephron.

4) It could have been reabsorbed after being filtered into the glomerulus.

5) Aldosterone regulates balance of sodium and potassium. Aldosterone stimulates Na+ absorption and K+ excretion in the kidney. This happens because the cell transcribes and translates more ion transporters to be inserted in the membrane. Aldosterone targets the principal cells of the distal tubule and collecting ducts, binding to a cytoplasmic hormone receptor and entering the nucleus to stimulate transcription of genes involved in ion transport.