Effect of water calcium, copper, and silver on branchial Na < sup > + < /sup > permeability in a characid and cichlid fish

Comp Biochem Physiol A Mol Integr Physiol. 2023 Nov 11:111553. doi: 10.1016/j.cbpa.2023.111553. Online ahead of print.ABSTRACTWe tested the hypothesis that water Ca2+ is involved in control of branchial Na+ permeability in low pH tolerant convict cichlids and black neon tetras. We measured Na+ efflux in water with different Ca2+ concentrations during exposure to low pH, silver, and copper, at levels which are known to stimulate Na+ efflux. For convict cichlids at pH 7.5 exposure to 0 μmol L-1 Ca2+caused Na+ efflux to rise 2.5 times above controls at 100 μmol L-1 Ca2+. However, raising [Ca2+] to 500 μmol L-1 had no effect. Upon exposure to pH 3.5 (control [Ca2+]) Na+ efflux rose almost 5× and increasing the [Ca2+] 5-fold did not reduce the magnitude of stimulation. Exposure to 1 μmol L-1 silver and 25 μmol L-1 copper stimulated Na+ efflux 7×, and 2×, respectively. Raising [Ca2+] concentration during metal exposure halved the stimulation of Na+ efflux caused by silver, and eliminated the stimulation elicited by copper. For black neon tetras raising or lowering water [Ca2+] had no effect on Na+ efflux at pH 7.5. Exposure to pH 3.5 caused Na+ efflux to rise 2.5× but changing [Ca2+] had no effect. Exposure to 1 μmol L-1 silver, or 25 μmol L-1 copper caused Na+ efflux of tetras to rise 4-fold and 3-fold, respectively. Raising [Ca2+] during silver exposure reduced the stimulation of Na+ efflux by about 50%, but during copper exposure increased [Ca2+] had no effect on stim...
Source: Comparative Biochemistry and Physiology. Part A, Molecular and integrative physiology. - Category: Physiology Authors: Source Type: research