Modification by diet and environmental temperature of enterocyte function in piglet intestine.

Intestinal morphology, enterocyte life span and alanine transport have been studied in the small intestine of piglets fed different amounts of food at high and low environmental temperatures. Villus height and crypt depth were both greater in pigs maintained on a high energy intake. Environmental temperature produced negligible effects on intestinal structure. Enterocyte life span increased from 45 h in pigs kept at 35 degrees C to about 70 h in animals living at 10 degrees C. A low energy intake prolonged enterocyte life span at an environmental temperature of 10 degrees C. The Na-dependent fraction of alanine uptake, judged by analysis of autoradiographs and by measurement of alanine-dependent short-circuit current, was greater in intestines taken from pigs maintained on a restricted diet. This effect, which appeared to be due to changes in the number of carriers (Jm) rather than the apparent affinity of the carrier for the amino acid (Km) was most noticeable using intestines taken from pigs kept at 10 degrees C. The Na-independent fraction of alanine uptake remained unchanged either by alterations in diet or in the environmental temperature at which pigs were kept. Restricting the diet of pigs at low environmental temperature leads to a relative increase in the capacity of the intestine to absorb alanine through an Na-dependent process. This increase appears to be caused by an extension of enterocyte life span rather than by any change in the time of onset or rate of expression of carrier function in a single enterocyte.