Respiration rates, ATP content and ionic regulation in hepatocytes of starving lamprey during the pre-spawning period of their life cycle

During the winter pre-spawning migration, lampreys Lampetra fluviatilis sto p feeding, and their liver metabolism is reduced substantially. Aerobic ATP production in hepatocytes decreased to one third and ATP content decreased by 50% as compared with the values in autumn. In spite of the decrease of endogenous and phosphorylating (oligomycin-sensitive) respiration in winter , the oxygen consumption used to drive sodium and potassium pumping through Na,K-ATPase activity (ouabain-sensitive respiration) remained virtually co nstant. Consequently its share in phosphorylating respiration increased fro m 16.3% in November to 54.2% in February. Potassium influx was similar with in the range of ATP content between 2.5 and 1 nmol 10(-6) cells and decreas es only in hepatocytes which contained <0.8 nmol ATP 10(-6) cells. (C) 2001 The Fisheries Society of the British Isles.