title: Dynamics of hepatic lactate and glucose balances during prolonged exercise and recovery in the dog.
abstract: The present experiments were undertaken to assess dynamics of hepatic lactate and glucose balance in the over-night-fasted dog during 150 min of moderate-intensity treadmill exercise and 90 min of exercise recovery. Catheters were implanted chronically in an artery and portal and hepatic veins 16 days before experimentation. 3-3H-glucose was infused to determine hepatic glucose uptake, as well as tracer-determined glucose production by isotope dilution (Ra). At rest, net hepatic lactate output was 0.33 +/- 0.15 mg.kg-1.min-1 and increased to 2.26 +/- 0.82 mg.kg-1.min-1 after 10 min of exercise, after which it fell such that the liver was a net lactate consumer by the end of exercise and through recovery. In contrast to the rapid release of lactate, net hepatic glucose output rose gradually from 2.58 +/- 0.20 mg.kg-1.min-1 at rest to 8.87 +/- 0.85 mg.kg-1.min-1 after 60 min of exercise, beyond which it did not change significantly until the cessation of exercise. Hepatic glucose uptake at rest was 1.38 +/- 0.42 mg.kg-1.min-1 and did not change appreciably during exercise or recovery. Absolute hepatic glucose output (net glucose output plus uptake) rose from 3.96 +/- 0.45 mg.kg-1.min-1 at rest to 10.20 +/- 1.09 mg.kg-1.min-1 after 60 min of exercise and was 9.65 +/- 1.15 mg.kg-1.min-1 at 150 min of exercise. Ra rose from 3.34 +/- 0.21 mg.kg-1.min-1 to 7.58 +/- 0.73 and 8.59 +/- 0.77 mg.kg-1.min-1 at 60 and 150 min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232.
authors.forename: D H
authors.initials: DH
authors.lastname: Wasserman
authors.forename: D B
authors.initials: DB
authors.lastname: Lacy
authors.forename: D R
authors.initials: DR
authors.lastname: Green
authors.forename: P E
authors.initials: PE
authors.lastname: Williams
authors.forename: A D
authors.initials: AD
authors.lastname: Cherrington
mesh_terms: D000818:Animals; D004285:Dogs; D005260:Female; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D006499:Hepatic Artery; D006503:Hepatic Veins; D007328:Insulin / Q000097:blood; D007773:Lactates / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008102:Liver Circulation; D008297:Male; D005082:Physical Exertion; D011168:Portal System; D013997:Time Factors
chemical_list: D007328:Insulin; D007773:Lactates; D005934:Glucagon; D005947:Glucose