THE EFFECT OF HOMOGENATES AND EXCRETORY SECRETORY PRODUCTS OF NIPPOSTRONGYLUS-BRASILIENSIS AND OF ACETYLCHOLINESTERASE ON THE AMPLITUDE ANDFREQUENCY OF CONTRACTION OF UNINFECTED RAT INTESTINE IN-VITRO/

Whole worm homogenates and excretory/secretory (E/S) products of adult Nippostrongylus brasiliensis significantly decreased the amplitude of contractions of segments of uninfected rat intestine maintained in an organ bath, with significantly larger volumes of E/S products being r equired to bring about a similar decrease to that caused by the whole worm homogenate. Boiled samples of homogenate and E/S products signifi cantly decreased the amplitude of contractions of uninfected rat intes tine, but larger volumes were needed than with unboiled samples. Frequ ency of contraction was unaltered by homogenates or E/S products. When electric eel AChE was injected into the lumen of segments of uninfect ed rat intestine maintained in an organ bath there was no significant decrease in the amplitude of contractions. These results suggest that substances present in the E/S products of N. brasiliensis significantl y reduce the amplitude of contractions of uninfected rat intestine in vitro and that the biochemical holdfast responsible for this phenomeno n may not be AChE.