Comparative lactic acidosis in fishes following pesticide stress

Abstract

Lactic acid levels were estimated in blood, liver, muscle and heart-tissues of a water-breathing fish, Sarotherodon mossambicus and of an air-breathing fish, Channa striatus under control and 3 ppm sevin-exposed (for 24 h, 48 h, 72 h and 96 h) conditions. Based on the results obtained, the following points were concluded: (1) The water-breathing fish, S. mossambicus appeared to suffer severe lactic acidosis to a greater extent than that of the air-breathing fish, C. striatus during early periods (24 h) of sevin exposure. (2) Following prolonged exposure for 48 h and 72 h, S. mossambicus exhibited adaptive withdrawal of lactic acid from blood and muscle possibly into liver favouring the synthesis of glycogen (glycogenesis through Cori cycle) from lactic acid under sevin toxicity. (3) The reduction in lactic acid level in blood, liver and muscle of the air-breathing fish, C. striatus, under sevin exposure for 24 h and 48 h was suggestive of a possible oxidation of lactic acid (by rechannelling lactic acid into Krebs cycle via pyruvic acid) to meet the energy demand under sevin toxicity. (4) The onset of mild lactic acidosis in blood, muscle and liver during 72 h of sevin exposure of C. striatus suggested a possible inhibition of enzyme battery in the conversion of lactic acid into pyruvic acid.