Age-related differences in receptors for Escherichia coli heat-stable enterotoxin in the small and large intestine of children

Abstract

Escherichia coli that produce heat-stable enterotoxin are a worldwide cause of diarrheal disease, especially in children. We examined small and large intestinal specimens from children of various ages for the presence of E. coli heat-stable enterotoxin receptors and determined whether the number of receptors or the binding affinity of these receptors was related to the age of the child. We observed specific binding of 125I-heat-stable enterotoxin to all small intestinal and colonic specimens. However, a greater number of receptors per microgram of membrane protein were present in infants and the number of receptors rapidly decreased with increasing age. We also observed that increased heat-stable enterotoxin stimulation of guanylate cyclase was correlated with increased receptor density. We suggest that a greater number of gastrointestinal receptors for heat-stable enterotoxin, capable of activating more guanylate cyclase, may contribute to the increased severity of diarrhea noted in young children exposed to enterotoxigenic E. coli.