VITAMIN-D-3-INDUCED CALCEMIC AND PHOSPHATEMIC RESPONSES IN THE FRESH-WATER MUD EEL AMPHIPNOUS-CUCHIA MAINTAINED IN DIFFERENT CALCIUM ENVIRONMENTS

Vitamin D-3 (100 ng 100 g body weight(-1) day(-1)) was administered in traperitoneally (ip) to the freshwater mud eel Amphipnous cuchia kept in artificial freshwater, calcium-free freshwater, low-calcium freshwa ter (0.2 mmol/l CaCl2) or calcium-rich freshwater (13.4 mmol/l CaCl2) for 15 days. Analyses of serum calcium and phosphate levels were perfo rmed on days 1, 3, 5, 10 and 15 after the beginning of the experiment (six eels from each group at each interval). Administration of vitamin D-3 elevated the serum calcium [maximum elevation occurred at day 10 in artificial freshwater (vehicle: 10.55 +/- 0.298, vitamin D: 13.90 /- 0.324), low-calcium freshwater(vehicle: 11.17 +/- 0.220, vitamin D: 12.98 +/- 0.297) and calcium-rich freshwater (vehicle: 11.24 +/- 0.37 3, vitamin D: 14.24 +/- 0.208) whereas it occurred at day 5 (vehicle: 8.42 +/- 0.253, vitamin D: 11.07 +/- 0.328) in calcium-free freshwater ] and phosphate levels [maximum elevation at day 15 in artificial fres hwater (vehicle: 4.39 +/- 0.105, vitamin D: 5.37 +/- 0.121), calcium-f ree freshwater (vehicle: 4.25 +/- 0.193, vitamin D: 5.12 +/- 0.181), l ow-calcium freshwater (vehicle: 3.93 +/- 0.199, vitamin D: 5.28 +/- 0. 164) and calcium-rich freshwater (vehicle: 3.77 +/- 0.125, vitamin D: 5.46 +/- 0.151)] of the fish maintained in the above mentioned environ mental media, but the responses were more pronounced in the fish kept in calcium-rich media.