Consequences of partial and subtotal colectomy in the rat.

Rats were subjects to right hemicolectomy (including removal of the caecum), left hemicolectomy or subtotal colectomy. Body weight resumed and maintained a rate of increase very similar to that in control rats. After hemicolectomy, food intake showed no change. Faecal weight increased by about one-third after right hemicolectomy, but did not increase after left hemicolectomy. After right hemicolectomy, the remaining--that is, downstream--portion of the colon showed increase in weight, and so did the (upstream) small intestine, in which the increase involved all three-thirds of its length and was predominantly mucosal. No such changes in the remaining colon or in small intestine were found after left hemicolectomy. After subtotal hemicolectomy, rats ate 30-40% more food than control rats, and faecal weight increased 60% at three months after operation. Study of energy intake and output indicated diminished absorption. All three-thirds of the small intestine showed increase in weight, predominantly mucosal in the upper two-thirds and predominantly seromuscular in the lowest third; villi were taller at all levels. Evidence suggests that the increase in food intake is not due to cessation of coprophagy, and that the small intestine changes are not due solely to increased food intake and occur when the colon is bypassed but not removed.