Rapid development of hypocalcemia in total nephrectomized (NX) rats. Plasma Ca2+ concentrations in sham, NX, TPTX, and NX-TPTX rats. Plasma Ca2+ in the NX rats declined rapidly with development of significant hypocalcemia already within 60 minutes, as compared to sham rats (p < 0.01). TPTX resulted as expected in significant hypercalcemia (p < 0.05) within 60 minutes. The increase in plasma Ca2+ was significantly lower in NX-TPTX rats, than in TPTX rats, (p <0.05).