Cathartic activity of spasmogens in mice, rats and guinea pigs

To examine the effect of spasmogens on propulsive motility in the intestine, cathartic activity o drugs was investigated. Mice, rats and guinea pigs were individually observed in cages with 20 separate small rooms in which a sheet of filter paper covered the bottom of cage for observation of the feces. The effect was evaluated 1 hr after drug administration. Cathartic activity of spasmogens was the most marked in mice followed by rats, but was rarely observed in guinea pigs. Cholinergic drugs and cholinesterase inhibitors had a cathartic effect in mice and rats, but the activity differed. Drugs such as acetylcholine and physostigmine produced a low cathartic activity even at sublethal and lethal doses. Other drugs as bethanechol, pilocarpine and neostigmine had a dose dependent cathartic effect at doses below lethal ones and were found to be clinically useful for intestinal relaxation after laparotomy. Among autacoids which contract the intestine by direct action on smooth muscles, histamine and bradykinin had no cathartic effect in mice and rats. 5-HT and prostaglandin E2 were dose dependent with a marked cathartic effect in both species. 5-HTP produced the same cathartic activity as that seen with 5-HT in mice, but had no cathartic effect in rats. The cathartic effect of BaCl2 was low, but dose dependent in both species. We recommend this method for the study of the effect of various compounds on the propulsive motility of the intestine.