Effect of Cyclopropane on Isolated Intestinal Muscle

Abstract

It has been shown 1 that the in vitro effects of ether and ethylene on isolated intestinal muscle agree substantially with experimental evidence in vivo 2 and with clinical observations 3 that ether causes marked loss of intestinal tone and contractility while ethylene does not. It was also shown 1 that divinyl oxide, possessing a chemical structure combining characteristic features of both, is more like ethylene than ether in this respect as in other physiological actions. No reports so far seem to have been made regarding the effect of cyclopropane on intestinal muscle, although Waters and Schmidt 4 found slightly less post-operative intestinal distension after abdominal surgery with cyclopropane than with ether.

Segments of intestinal muscle about 2 cm. in length from the jejunum of a newly killed rabbit were suspended by the Magnus method from a muscle lever, in oxygenated Locke's solution at 37.5°C. Cyclopropane in concentrations in oxygen employed clinically was bubbled through the solution in such a way as to bring it in equilibrium with the gaseous mixture as quickly as possible.

Thirty segments from 6 rabbits were tested for reactivity with acetylcholine and epinephrine in appropriate concentrations and washed carefully before applying the cyclopropane. In each case after bubbling into the bath concentrations of 101% to 25% cyclopropane in oxygen there was an increase in tone of the intestinal muscle with a decrease in amplitude of contraction (Figs. 1 and 2). Upon washing the cyclopropane from the bath there was a gradual return of the segment to its normal activity. The degree of gut stimulation was found to be roughly proportional to the concentration of cyclopropane up to 25% in oxygen at which maximum effect seemed to be obtained.