An investigation of the loss of bound calcium from the gills of the brown trout, Salmo trutta, in acid media

Abstract

1. 1. The loss of surface-bound calcium from isolated gills of the brown trout, Salmo trutta, is examined using a modified tracer efflux technique. Gills were effluxed in neutral and acid de-ionised water and in media containing Na + or Ca 2+ or a variety of concentration ratios of both ions. 2. 2. Surface-bound calcium is removed from the gills more rapidly in acid than in neutral conditions. 3. 3. Calcium is bound to 2 distinct types of binding site on the gill surface but only one type of site appears to be involved in the control of membrane permeability. 4. 4. In acid conditions surface-bound calcium is lost less rapidly from the gills of an acid tolerant strain of brown trout (from a low Ca 2+ environment) than from the gills of a non-tolerant strain (from a high Ca 2+ environment). 5. 5. Sulphuric acid displaces surface-bound calcium more effectively than either nitric or hydrochloric acids.