ADRB3 and Hypercalcemia: We also show that β3-AR−/− mice have normal plasma levels of Na+, K+, Cl−, and Ca++ indicating that their polyuric phenotype is neither induced by hypercalciuria/hypercalcemia nor by hypokalemia.34, 35, 36 In addition, the polyuria in β3-AR−/− mice is not a consequence of an increased GFR, which is comparable to that in β3-AR+/+ mice.