Absorption of lactose from colon of newborn piglet.
Piglets in three age groups (1-3, 9-11, and 16-25 days after birth) were used for in vivo colonic perfusions. Studies compared an isosmolar (312 mosM) with a high osmolar (551 mosM) solution and two equimolar substrates (with hexose concentrations of 73.1 mM), lactose and glucose-galactose. From the isosmolar perfusates, lactose absorption was 0.43 +/- 0.04 in the 18-20 day olds and 1.04 +/- 0.2 mumol.cm-1.min-1 in the 1-3 day olds; absorption from the glucose-galactose solution was negligible in all age groups (less than 0.05 +/- 0.05 mumol.cm-1.min-1). From the high osmolar perfusate, lactose absorption also exceeded that of glucose and galactose. In a third set of perfusion studies, the concentration of lactose was varied between 15 and 240 mM perfusate. Five-day-old animals absorbed 67% more lactose than 18-day-old animals; the right colon absorbed 57% more than the left. Lactose absorption, correlated with its concentration in the perfusate (r = 0.99), was nonsaturable at concentrations up to 240 mM, and was correlated with the uptake both of sodium (r2 = 0.59 for young and 0.64 for older neonates) and of chloride (r2 = 0.55 for young and 0.31 for older neonates). The results suggest that lactose may be removed from the colon without apparent cleavage by beta-galactosidase.
Murray
R D
RD
Department of Pediatrics, Ohio State University, Children's Hospital, Columbus 43205.
Ailabouni
A H
AH
Powers
P A
PA
McClung
H J
HJ
Li
B U
BU
Heitlinger
L A
LA
Sloan
H R
HR
D000818:Animals; D000831:Animals, Newborn; D050260:Carbohydrate Metabolism; D002712:Chlorides / Q000378:metabolism; D003106:Colon / Q000378:metabolism* / Q000502:physiology; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000201:enzymology / Q000378:metabolism; D007583:Jejunum / Q000201:enzymology; D043322:Lactase; D007785:Lactose / Q000378:metabolism*; D009994:Osmolar Concentration; D010477:Perfusion; D012964:Sodium / Q000378:metabolism; D013552:Swine; D014867:Water / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
D002712:Chlorides; D014867:Water; D012964:Sodium; D043322:Lactase; D001616:beta-Galactosidase; D007785:Lactose