Final answer:
The release of ADH in amphibians causes an increase in the number of aquaporin water channels in the bladder and distal convoluted tubule, facilitating greater water reabsorption and resulting in more concentrated urine.
Step-by-step explanation:
When ADH (Antidiuretic Hormone) is released in amphibians, it has a specific effect on the physiology of their kidneys, particularly in the collecting ducts of the renal system. ADH prompts the epithelial cells lining the renal collecting tubules to move aquaporin water channels from the interior of the cells to the apical surface, where they are inserted into the cell membrane. This increases the water permeability of these cells, leading to a significant increase in water reabsorption from the urine back into the bloodstream. As a result, the number of aquaporins in the bladder and distal convoluted tubule increases, which allows for more water to be absorbed and a more concentrated urine to be produced.