Effects of acute exposure to methyl parathion on carbohydrate metabolism of Indian catfish (Heteropneustes fossilis)

Abstract

Exposure of the Indian catfish (Heteropneustes fossilis) to a high sublethal concentration of 5.6 p.p.m. (0.8 of the 96 hr LC50) of methyl parathion for 3, 6, 12, 48, and 96 hrs affected carbohydrate metabolism. Muscle glycogen levels decreased significantly at 3, 6, 12 and 96 hrs; liver glycogen content declined at 6 hrs but there was a resynthesis of hepatic glycogen stores at 12 hrs. Blood glucose levels in fish were elevated at 3 and 6 hrs. Mean values for blood pyruvate were elevated significantly at 6, 12, and 96 hrs. Blood lactate level was elevated at 3 hrs but hypolactaemia resulted at 48 and 96 hrs in pesticide-treated fish. The observed effects of methyl parathion on carbohydrate metabolism in fish are discussed in relation to acute stress syndrome. Measurement of carbohydrate metabolites in fish for 3 hrs or longer could prove useful as a rapid method for evaluating toxicity of pesticides and other toxicants.