STUDY OF EFFECT OF ERYTHROMYCIN BASE ON GASTROINTESTINAL SMOOTH MUSCLES IN LABORATORY ANIMALS IN-VITRO

Background – Drugs affecting gastrointestinal motility find place in the treatment of gastrointestinal motility disorders. Objective: To evaluate the effect of erythromycin base on the isolated tissue of rabbit jejunum, guinea pig ileum & rat colon in vitro and also to see whether it alters the contractile responses induced by acetylcholine. Materials and Methods: a) Rabbit jejunum experiment: After recording the baseline spontaneous rhythmic contractions, erythromycin was added to the organ bath and the responses were taken every 3 min for 30 min. The effect on frequency & the amplitude of spontaneous contractions were noted. (Erythromycin doses used – 1, 2, 10 & 20 µM; in six rabbits). b) Guinea pig ileum & rat colon experiment: Initially responses were recorded with acetylcholine (1-100µg). After giving wash, erythromycin was added to the organ bath and response was recorded for 30 seconds; then after a contact period of 3 min with erythromycin, responses to selected dose of acetylcholine were recorded again. (Erythromycin doses used – 100, 300 500 & 1000 µM; in six guinea pigs & rats each) Results: In isolated rabbit jejunum, erythromycin (1-20 mM) produced increase in basal tone and higher concentrations (10-20 mM) reduced both rate & height of spontaneous contractions. In isolated guinea pig ileum & rat colon, erythromycin showed no effect on basal tone. Erythromycin (100-300 mM) reduced the magnitude of response to acetylcholine induced contractions in guinea pig ileum, but increased the magnitude of acetylcholine induced contractions in rat colon in dose dependent manner. Conclusion: Erythromycin has different effects on different parts of the gastrointestinal tract in different species of animals