THE INTRINSIC REFLEXES IN THE COLON

Abstract

With anesthetized dogs the intrinsic reflexes were studied in the denervated colon.
(1) The intrinsic reflexes consist of two different kinds of reflexes as in the small intestine; namely, one is elicited from the mucosa and the other from the muscular coats
(a) When the mucosal surface is stimulated mechanically (e.g., stroking) or chemically (e.g., HCl), the excitatory state is elicited on the oral side of the stimulated spot, giving rise to an increase in the strength of contraction waves, while the inhibitory state on the anal side, eliciting a decrease in the strength of contraction waves.
(b) When the muscular coats are stimulated mechanically or chemically, the inhibitory state is elicited on both sides of the stimulated spot, the effect being always stronger on the anal side than on the oral.
(2) The mucosal reflex is completely abolished after a large dose of hexamethonium bromide has been administered intravenously and locally, but the muscular reflex does not. As a consequence two reflexes appear to be essentially different from one another in their mechanism.
(3) From the results described above the causes of discrepancies among the results obtained by previous authors were discussed. The mechanism of the normal movements of the colon was also considered.