Effect of deoxycholic acid on colonic motility in the rabbit

The purpose of the study was to determine the effect of the bile salt, deoxycholic acid, on colonic myoelectrical and contractile activity recorded from a loop of proximal colon in the anesthetized rabbit. Myoelectrical activity was recorded from bipolar electrodes attached to the serosal surface of the proximal colon. Contractile activity of the circular smooth muscle was measured with a strain gauge attached in the circular direction on the serosal surface of the colonic loop. The colonic slow wave frequency was 12.5 +/- 1.1 cycles/min. The slow wave frequency throughout the loop was homogeneous with a low coefficient of variation of the slow wave frequency (5.8 +/- 0.3). There were spike potentials superimposed on 78.1 +/- 3.4% of the slow waves. The addition of 8 or 16 mM deoxycholic acid did not change the slow wave or spike activity. However, deoxycholic acid stimulated a dose-dependent increase in migrating action potential complexes. These complexes were associated with a forceful contraction of the circular smooth muscle that propelled luminal contents in the direction of the burst. Deoxycholic acid also stimulated an increase in luminal fluid content.