Title

Rubidium Uptake Is Increased in Shore Crabs, Carcinus maenas, Acclimated to Dilute Seawater

Document Type

Article

Publication Date

2001

Abstract

In dilute seawater, Carcinus maenas hyperosmoregulates by actively absorbing Na, K, and Cl. Here we characterize K uptake using a novel technique. Rb was used as a tracer for K transport, and hemolymph Rb levels were measured using cation chromatography. Hemolymph Rb was detectable at 0.1 mmol L−1, which enabled determination of initial rate of Rb uptake. Crabs maintained for 3 wk in dilute artificial seawater (35% ASW crabs) maintained Na and K above the level of the external media and had elevated Na‐K‐ATPase activity in the posterior gills. In assay conditions matched to 100% ASW, Rb uptake was the same in 35% ASW crabs ($0.45\pm 0.04$ μmol g−1 h−1) and in crabs acclimated to normal seawater (100% ASW crabs, $0.49\pm 0.05$ μmol g−1 h−1). In assay conditions matched to 35% ASW, Rb uptake was greater in 35% ASW crabs ($0.28\pm 0.03$ μmol g−1 h−1) compared with 100% ASW crabs ($0.10\pm 0.04$ μmol g−1 h−1). Low external [Rb] or reduced salinity were found to contribute independently to the difference between 100% ASW and 35% ASW crabs. Thus, whole‐body Rb uptake in crabs can be measured by cation chromatography, and Rb uptake is greater in 35% ASW crabs than in 100% ASW crabs.

Journal

Physiological and Biochemical Zoology

Volume

74

Issue

5

First Page

724

Last Page

732