The influence of exercise–handling stress on blood lactate, acid–base, and plasma glucose status of northern pike (Esox lucius L.)

Changes in blood lactate, pH, Pco2, and plasma and glucose were measured during recovery from exercise–handling stress in chronically cannulated northern pike (Esox lucius L.). Exercise was induced by lifting pike out of water (three 30-s periods of emersion alternated with 30-s periods of water submersion), while they were inside tubular plastic chambers. Large depressions in blood pH and plasma occurred within minutes after exercise. Initially, the acidosis was of mixed respiratory (elevated Pco2) and metabolic (H+ release from the muscle) origin. Although the respiratory acidosis was corrected in 2 h, 8 h was required to return blood pH to preexercise levels. A large accumulation of lactate anion in the blood occurred after exercise, the increase by 2 h (12.8 mmol L−1), being approximately equal to the metabolic acid load. These results conflict with previous reports on muskellunge (Esox masquinongy M.), in which blood lactate elevation following exercise was small (2.5 mmol L−1) and greatly exceeded b...