Toxicidade aguda, efeitos metabólicos e hematológicos subletais do fenol em pacu Piaractus mesopotamicus (Holmberg, 1887)

Abstract

Phenol compounds and their derivatives are usually found in wastewaters. They may rise in aquatic environments from industry, sewage and country-farm wastes. In the present study we intended to determine the acute toxicity of phenol (LC50-96 hours) and its effects on intermediary metabolism and hematology of pacu exposed to sublethal concentration for 96h. In addition, recovery was evaluated after one week. For such, glucose, pyruvate, lactate, protein, amino acids, ammonia and glycogen were gauged in liver, white muscle and plasma after 96h of phenol exposure. Sodium, potassium and chloride were quantified in plasma. Activities of ALAT (alanine aminotransferase), ASAT (aspartate aminotransferase) and LDH (lactate dehydrogenase) were assayed in white muscle and liver. The hematological parameters: hematocrit, hemoglobin concentration and red blood cell counting, plus the hematimetric indices: MCV, MCH, MCHC were determined. At the end of the recovery period the tissue metabolites were quantified, ions concentration was estimated in the plasma and haematological parameters were determined. The results depicted a CL50-96h of 33 mg/L for pacu. After 96h of sublethal exposure to phenol it was observed: protein decrease, free amino acids increase and activity rise of ALAT and ASAT in white muscle. This is very suggestive of muscle proteolysis. In liver and plasma the levels of glucose, free amino acids and lactate were augmented. Hyperlactemia may be a sign of anaerobic metabolism increase. Augmented values of hematocrit, total hemoglobin and red cell counting may be ought to anaerobic metabolism. After recovery, the fish showed muscle glycogenolysis and reduction of pyruvate levels. The hyperlactemia was still remained. In the liver, protein levels were diminished and glycogen, glucose and lactate were increased. In this work, the stress and toxicity caused by phenol in pacu were clearly observed as well as the metabolic and hematologic processes were visibly affected.