Adaptation of electrolyte transport in rat large intestine after proximal resection. I. Cecum and colon after 60% jejunoilectomy.

Electrolyte transport was studied in rat cecum and colon adapting to 60% resection of the small intestine. Four weeks after surgery, the absorbing gross surface area, dry and wet weight, net absorption in vivo of sodium, chloride and volume, net potassium secretion, transmural electrical potential difference and mucosal Na-K-ATPase specific activity were determined. In the cecum, all tissue mass parameters were increased compared to sham-operated controls. Net transport was stimulated per organ but not per unit mass, and potential difference and Na-K-ATPase remained unaffected. In the colon, surface area and wet weight increased slightly while dry weight and electrolyte transport were not influenced. Thus, by enlargement without a change in cell function, the cecum but not the colon contributes to electrolyte homoeostasis after 60% jejunoilectomy in the rat. Na-K-ATPase specific activity and electrical potential difference were higher in the colon than the cecum, suggesting segmental heterogeneity of the larger bowel with respect to Na-K-ATPase-linked active sodium absorption.