Carbachol stimulates inositol phosphate formation transiently in Trypanosoma cruzi

The effect of carbachol on Trypanosoma cruzi epimastigote forms was studied. Suspension of epimastigote cells prelabelled with myo[3H]-inositol were incubated at 28 degrees C in the presence of carbachol. The levels of inositol phosphate after the challenge of carbachol were determined to see if the accumulation of inositol phosphate was time-dependent. In the presence of Li+ the levels of IP3 and IP4 were significantly increased during the 3 min. with a peak at 1 min. after the carbachol challenge. This effect was suppressed by atropine. The results show that carbachol influences rapid changes in phosphoinositide metabolism and they are time-dependent involving second-messenger systems associated with the generation of IP3. In addition they would suggest that this IP3 generation is through a receptor-mediated process linked to phospholipase C by a G-protein.