In vivo estimation of lactose hydrolysis in premature infants using a dual stable tracer technique.
To investigate their putative capacity for lactose digestion, primed continuous orogastric infusions of [1-13C]glucose and D-[1-13C]lactose were administered on consecutive days to five premature infants (30-31 wk gestation, 15-32 days of age), who were fed by orogastric infusions of human milk or formula. By monitoring the plateau isotopic enrichment of plasma glucose using isotopomers containing the entire derivatized glucose molecule or C-2 through C-6, we were able to distinguish label appearing in the peripheral circulation deriving from unmetabolized glucose from that arising from recycled or fermented glucose (or lactose). Isotopic enrichment of the C-1 of glucose, corrected for recycling, was then calculated during each tracer infusion, and the fraction of dietary lactose subjected to in vivo hydrolysis was estimated from these values and the respective tracer infusion rates, assuming similar absorptive and metabolic fates of labeled glucose arising from either tracer. This fraction averaged 1.02 +/- 0.16 (SD), suggesting that lactose digestion is efficient by 34-wk postconceptional age.
Kien
C L
CL
Department of Pediatrics, Ohio State University, Columbus.
Ault
K
K
McClead
R E
RE
D001639:Bicarbonates / Q000494:pharmacology; D002245:Carbon Dioxide; D002247:Carbon Isotopes; D005947:Glucose / Q000378:metabolism; D006801:Humans; D006859:Hydrogen; D006868:Hydrolysis; D007231:Infant, Newborn; D007234:Infant, Premature / Q000378:metabolism* / Q000502:physiology; D007785:Lactose / Q000378:metabolism*; D008954:Models, Biological; D012119:Respiration
D001639:Bicarbonates; D002247:Carbon Isotopes; D002245:Carbon Dioxide; D006859:Hydrogen; D005947:Glucose; D007785:Lactose