ACTION OF CISAPRIDE ON RAT COLONIC SECRETION

The stimulating effect of cisapride on the motility of the digestive t ract is well known. However, there are only a few studies on the influ ence of this drug on the absorptive or secretory activity of the colon ic mucosa. In the present study, the ability of cisapride to alter the mural transport of water and electrolytes in the colon and its effect s on mucus secretion and albumin permeation were studied. The effects of cisapride on the rat colon in vivo were studied under different con ditions, by means of an instillation of sodium acetate solution at pH 6.9, which induced absorption of water and electrolytes, and in two mo dels of colonic secretion, one employing the instillation of an acetic acid solution at pH 2.9 and the other, an intravenous infusion, of 5- hydroxytryptamine (sero-tonin) 45 mug . kg-1 . min-1 together with int racolonic instillation of sodium acetate. Cisapride (iv.), at a dose o f 0.32 mg . kg-1, in rats whose colon was instilled with sodium acetat e (pH 6.9) induced an increase in sodium absorption and a reduction in water absorption. Cisapride (iv.), at doses of 0.32, 0.64 and 1.0 mg . kg-1, inhibited the secretion of water, Na+, Cl-, and mucus and the permeation of albumin induced by acetic acid instillation or by seroto nin infusion. It is concluded that the effect of cisapride on the colo nic mucosa varies in accordance with the functional mucosal conditions and that this action may be of clinical importance.