Effects of sulfide on K+ flux pathways in red blood cells of crucian carp and rainbow trout |
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| Authors: | S Völkel M Berenbrink N Heisler M Nikinmaa |
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| Institution: | (1) Institute of Veterinary Physiology and Institute of Physiology, University of Zürich, Zürich, Switzerland |
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| Abstract: | The effect of sulfide on K+ influx pathways was measured in red blood cells (RBCs) of sulfide-sensitive rainbow trout (Oncorhynchus mykiss) and sulfide-tolerant crucian carp (Carassius carassius). In trout RBCs, maximal inhibition of Na+, K+-ATPase was attained at 10  mol l–1 sulfide and amounted to 32% without being influenced by pH between 6.7 and 8.3. Ouabain-resistant K+ influx in the absence and presence of sulfide was insignificant at pH values between 6.7 and 7.7. At higher pH values ouabain-resistant K+ influx increased, but was inhibited to about 15% by 30 mol l–1 sulfide. In RBCs of crucian carp neither Na+, K+-ATPase nor ouabain-resistant K+ influx were affected by sulfide concentrations up to 850 mol l–1. Differences in sulfide-sensitivity of K+ influx between both species can be based upon different properties of the membrane transporter themselves. The reduced Na+, K+-ATPase activity in trout RBCs may also result from a slightly reduced (by 9%) ATP level after sulfide exposure. In addition, intracellular sulfide concentrations were higher in trout RBCs as compared to crucian carp. In trout, intracellular sulfide concentrations reached extracellular levels within 5 min of incubation whereas sulfide concentrations in crucian carp RBCs remained about 2-fold lower than extracellular concentrations. Although the physiological basis of sulfide-insensitive K+ influx in crucian carp RBCs is currently unknown it may contribute to the extremely high sulfide-tolerance of this species. |
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| Keywords: | Carassius carassius erythrocytes fish H2S K+ influx Na+ K+-ATPase Oncorhynchus mykiss |
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