Ca2+-dependent phosphatase and Ca2+-dependent ATPase activities in plasma membranes of eel gill epithelium--III. Stimulation of branchial high-affinity Ca2+-ATPase activity during prolactin-induced hypercalcemia in American eels.

Infusions of ovine prolactin for 10 days induced hypercalcemia in unfed American eels, Anguilla rostrata LeSueur, that tentatively was related to stimulation of branchial Ca2+-uptake mechanisms. Analysis of ATPase activities in the plasma membranes of the branchial epithelium in prolactin treated eels showed a specific stimulation of high-affinity Ca2+-ATPase. The results of this study form further evidence that the high-affinity Ca2+-ATPase activity represents the Ca2+-pump of the branchial epithelium.