Influence of cypermethrin toxicity on ionic regulation and gill Na+/K+-ATPase activity of a freshwater teleost fish Cyprinus carpio

The effects of acute and sublethal toxicity of cypermethrin, a synthetic pyrethroid insecticide on plasma electrolytes (Na+, K+ and Cl−) levels and gill Na+/K+-ATPase activity in a common carp Cyprinus carpio were examined. The 24 h LC50 value of cypermethrin for C. carpio was 1.86 ppm. During acute exposure, cypermethrin caused adverse effects in the form of hyponatreima, hypokalemia and hypochloremia and inhibition of gill Na+/K+-ATPase activity. In sublethal exposure to cypermethrin (0.186 ppm for 35 days), plasma Na+ was decreased throughout the exposure period except 7th day whereas plasma K+ level was increased up to 28th day, then declined. However, plasma Cl− level was decreased. Likewise, gill Na+/K+-ATPase activity was decreased as the exposure period extended. The present study indicates that cypermethrin was highly toxic to freshwater fish and ion levels in blood as measured by specific ion concentrations (Na+, K+ and Cl−) and changes in gill Na+/K+-ATPase activity may represent a sensitive and useful nonspecific biomarkers of chemical exposure and effects.