SOME FUNCTIONS OF THE LARGE INTESTINE OF THE HORSE

¹ The Rowett Research Institute, Bucksburn, Aberdeenshire

1. Techniques are described for cannulating the cæcum, ventral and dorsal colon of the horse.

2. Cæcal and colonic movements consisted of irregular contractions of which three types were recognized. Withholding food caused reduction in frequency or cessation of all contractions of cæcum and ventral colon; the dorsal colon remained unaffected. No evidence was obtained of antiperistaltic movements, as judged by the movement of carbon granules.

3. Adrenaline inhibited and carbamylcholine increased the frequency of the contractions. Histamine and posterior pituitary extract inhibited movements.

4. The concentration of volatile fatty acid in the liquor of the cæcum and ventral colon was decreased by withholding food and increased by feeding. This effect was not marked in the dorsal colon. The proportion of propionic acid in the ventral colon was greater than in the dorsal colon.

5. The rate at which cotton-threads disintegrated when suspended in the cæcum, ventral and dorsal colon decreased in an oral-caudal direction. Withholding food greatly reduced the rate of disintegration.

Note:

I wish to thank Dr. W. H. Pfander for the chromatographic separation of the fatty acids, Miss J. C. Brand for technical assistance, and Messrs. I.C.I. Limited for a gift of "Alkathene" tubing.