Sodium/Proton Exhange in Membrane Vesicles From Crab (Callinected Sapidus and Carcinus Maenas) Gill
نویسندگان
چکیده
Amiloride-sensitive Na+/H+ exchange in plasma membrane vesicles prepared by sucrose density gradient centrifugation of mitochondria-rich posterior gill cells in two species of crabs (Callinectes sapidus and Carcinus maenas) was examined by acridine orange fluorescence quenching. Sodium-loaded vesicles injected into sodium-free incubation medium (pHout = pHin) caused a quench in fluorescence indicating inward flux of H+. Addition of Na+, Li+ or K+ but not tetramethylammonium+ to the external medium relieved the quench, indicating outward flux of H+. Amiloride (0.5 mM) partially inhibited relief by Na+ or K+. Vesicles prepared from blue crabs (but not green crabs) acclimated to 5 ppt seawater showed greater total exchange activity per mg protein than vesicles from animals acclimated to 35 ppt seawater, suggesting that activation of Na+/H+ exchange may be part of the mechanism by which blue crabs are able to adapt to reduced salinities. SODIUM/PROTON EXCHANGE IN MEMBRANE VESICLES FROM CRAB (CALLINECTES SAPIDUS AND CARCINUS MAENAS) GILL
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