Anion Concentration in Cecal Content of Germ-free and Conventional Mice ∗

Abstract

Summary

Correlation between cecal size and the ionic composition of cecal content was determined in conventional mice, germ-free mice, germ-free mice fed with Cl-resin diet, germ-free mice monocontaminated with Clostridium difficile, and conventional mice treated with penicillin. Shrinkage of the cecum is best correlated with increased chloride and bicarbonate concentration; and enlargement of the cecum with decreased concentration. From these findings it was concluded that availability of chloride or permeable anion in the cecal content is the primary factor to control cecal size.