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Renal Na,K-ATPase and osmoregulation in the crayfish, Procambarus clarkii

1994; Elsevier BV; Volume: 107; Issue: 2 Linguagem: Inglês

10.1016/0300-9629(94)90392-1

0300-9629

Russell G. Sarver, Monica A. Flynn, Charles W. Holliday,

Aquaculture Nutrition and Growth

The freshwater crayfish, Procambarus clarkii, is a strong hyperosmoregulator in fresh water (FW) and 25% sea water (25% SW), and it weakly hyperosmoregulates in 50 and 75% SW. Procambarus clarkii produces a dilute urine in FW and 25% SW, but the urine becomes progressively more concentrated in 50% SW and is nearly isosmotic with the haemolymph in 75% SW. Antennal gland Na,K-ATPase ESA was highest in crayfish acclimated in FW and decreased significantly in animals acclimated for two weeks or two months in 50 and 75% SW. It is hypothesized: (a) that only a portion of the antennal gland Na,K-ATPase powers renal salt reabsorption and, thus, the production of dilute urine in P. clarkii, and (b) that P. clarkii may maintain high "basal" levels of antennal gland Na,K-ATPase to power other, non-osmoregulatory transport functions such as organic acid secretion into the urine and sugar and amino acid reabsorption from it. The time course of decreased antennal gland ESA after abrupt transfer of crayfish from FW to 50% SW is consistent with enzyme degradation.