THE EFFECTS OF CALCITONIN ON SERUM-CALCIUM LEVELS IN IMMATURE BROWN TROUT, SALMO-TRUTTA

Salmon calcitonin was administered intraperitoneally (0.1, 10, 1000 ng /100 g of fish) to freshwater-adapted, immature, female brown trout, S almo trutta, and changes in serum calcium levels were determined. The lowest dose (0.1 ng) had an effect similar to injection of saline (con trol), but the higher doses produced hypercalcemia. These latter effec ts were associated with increased serum levels of calcitonin. Maintain ing immature brown trout in waters containing 20 and 50 mM calcium chl oride resulted in a significant lowering of serum calcitonin with time although serum calcium levels remained stable. The extent of the decr ease in serum calcitonin increased with the higher levels of environme ntal Calcium. (C) 1995 Academic Press, Inc.