AJP - Regulatory, Integrative and Comparative Physiology, Vol 249, Issue 1 67-R72, Copyright © 1985 by American Physiological Society
Glucose and lactate kinetics in American eel Anguilla rostrata
I. Cornish and T. W. Moon
Simultaneous infusion of [6-3H]glucose and [U-14C]lactate was used to
calculate the turnover rate of glucose, the irreversible replacement rate
of lactate, and the rates of the exchange of carbon atoms between glucose
and lactate in free-swimming American eels (Anguilla rostrata) fed or food
deprived for 6, 15, and 36 (maturing) mo. The mean turnover rate of glucose
in fed animals averaged 1.0 mg X min-1 X 100 g-1, while the lactate
irreversible replacement rate was approximately 4.0 micrograms X min-1 X
100 g-1. The conversion of 35% of lactate carbon to glucose implied a
substantial Cori cycle activity, but this amounted to less than 1% of total
glucose production. Food deprivation for 6 mo altered few kinetic patterns,
except for an increased lactate irreversible replacement rate and a minor
increase in gluconeogenesis from lactate. After a 15-mo fast, glucose
turnover decreased to 0.09 +/- 0.02 mg X min-1 X 100 g-1. Plasma lactate
concentrations and production rates continuously increased during the
experiment. Maturing eels that had been food deprived for 36 mo maintained
glucose and lactate concentrations and kinetics similar to values in
animals food deprived for only 6 mo. This study stresses the importance of
carbohydrate in the metabolism of this species under fed and food-deprived
conditions and further supports the tolerance of Anguillid species to food
deprivation.
