Ionic and total calcium levels in the blood of the European eel (Anguilla anguilla): effects of stanniectomy and hypocalcin replacement therapy.

Removal of the corpuscles of Stannius (STX) in the freshwater European eel causes a marked increase in the concentrations of blood ionic calcium and protein-bound calcium. The hypercalcaemia peaks 20 days after STX and lasts at least another 20 days. In stanniectomized eels hypocalcin decreased both blood ionic and total calcium concentrations. The reduction of plasma total calcium concentration by hypocalcin is attributed to a reduction in blood ionic calcium concentration. We conclude that hypocalcin regulates blood ionic calcium levels in fish.