Osmoregulation and urea metabolism in the little skate Baja erinacea

نویسنده

  • LEON GOLDSTEIN
چکیده

GOLDSTEIN, LEON, AND KOY P. FORSTER. Osmoregulation and urea metabolism in the little skate Raja erinacea. Am. J. Physiol. 220(3) : 742-746. 197 1 .-Little skates, Raja erinacea, were transferred gradually (4 days) from full to approximately half-strength seawater. Steady-state conditions (with respect to solute and water balance) were established by the end of the dilution program. The skates were maintained in the dilute environment for an additional 4 days and then gradually (4 days) returned to 100 y0 seawater. Control groups were maintained in 100 y0 seawater. Hematocrits were 20 y0 lower and body weights were 18oj, higher in skates in dilute seawater than in controls. Plasma urea, chloride, and trimethylamine oxide concentrations were reduced 45, 30, and 27%, respectively, in dilute seawater. Urine flow and glomerular filtration rate were elevated sixand fourfold, respectively, in dilute seawater. The renal clearances of urea, chloride, and trimethylamine oxide increased 22, 6, and 13 times after environmental dilution. The percent filtered urea excreted by the kidneys increased sixfold in skates kept in 50% seawater. Total-body clearance of urea was similar in skates maintained in 100 and 50 $& seawater. Total urea excretion (production) was reduced in skates in dilute seawater. Thus, reduction in plasma urea concentration following environmental dilution was the result of increased renal clearance and decreased biosynthesis of the nitrogenous end product.

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Osmoregulation and urea metabolism in the little skate Raja erinacea.

GOLDSTEIN, LEON, AND KOY P. FORSTER. Osmoregulation and urea metabolism in the little skate Raja erinacea. Am. J. Physiol. 220(3) : 742-746. 197 1 .-Little skates, Raja erinacea, were transferred gradually (4 days) from full to approximately half-strength seawater. Steady-state conditions (with respect to solute and water balance) were established by the end of the dilution program. The skates ...

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تاریخ انتشار 2003