Objective: To investigate the effects of motilin agonists on intracellular Ca(2+) mobilization in primary cultured rat myenteric neurons.
Methods: Motilin-induced and erythromycin-induced intracellular Ca(2+) signaling was studied in primary cultures of rat myenteric neurons using the radiometric Ca(2+) indicator Furo3/AM with a laser confocal microscope.
Results: In Hank's solution, 10(-8), 10(-7), and 10(-6) mol/L motilin could elevate intracellular Ca(2+) concentration ([Ca(2+)]i) to the peak levels of 10.6-/+2.1, 15.9-/+1.2, and 30.6-/+3.7 respectively with their relative percentage change in fluorescent intensity of (40.1-/+6.3)%, (63.0-/+11.2)%, and (100.8-/+18.4)% respectively, indicating the dose-dependent effect of motilin on [Ca(2+)]i. In Hank's solution, 10 microg/ml erythromycin could induce the elevation of [Ca(2+)]i to the average peak of 23.2-/+5.6 with the relative percentage change in fluorescent intensity of (82.8-/+13.0)%. When pretreated with the antibody against motilin receptor in Hank's solution, the effect of 10 microg/ml erythromycin was almost inhibited completely.
Conclusion: Motilin can increase [Ca(2+)]i, and erythromycin also has this effect by binding to motilin receptor.