Accumulation of nitrate in the tissues of Penaeus monodon following elevated ambient nitrate exposure after different time periods

Penaeus monodon (10.56 +/- 0.71 g) exposed individually to 0.026 (control), 0.774, 3.646, 7.004, 21.234 and 36.079 mM nitrate in 25 ppt seawater were examined for nitrate accumulation in hemolymph, gill, eyestalk, heart, foregut, midgut, hepatopancreas and muscle after 1, 3, 6, 12 and 24 h, respectively. Concentration of nitrate in the tissues increased directly with ambient nitrate concentration and exposure time except for muscle. Following 24-h exposure to 3.646 mM nitrate, nitrate concentrations measured in the muscle (0.202 mumol g(-1)), hepatopancreas (0.330 mumol g(-1)), heart (0.527 mumol g(-1)), foregut (0.632 mumol g(-1)), gill (0.927 mumol g(-1)), hemolymph (0.946 mumol ml(-1)), eyestalk (1.214 mumol g(-1)), and midgut (1.529 mumol g(-1)), respectively. The concentration of muscle nitrate was the lowest, and the concentration of midgut nitrate was the highest among the tissues tested. P. monodon following exposure to ambient nitrate at 21.234 and 36,079 mM, nitrate accumulation measured in the muscle (0.854 and 0.980 mumol g(-1)), hepatopancreas (1.139 and 1.552 mumol g(-1)), heart (1.468 and 1.879 mumol g(-1)), foregut (2.195 and 3.341 mumol g(-1)), gill (2.398 and 3.325 mumol g(-1)), hemolymph (3.327 and 3.948 mumol ml(-1)), eyestalk (3.461 and 4.264 mumol g(-1)) and midgut (3.343 and 5.239 mumol g(-1) and never reached a plateau after 24 h. (C) 2002 Elsevier Science B.V. All rights reserved.