Effect of aluminum chloride on ascending colon of the rat

Aluminum chloride (2.48 X 10(-4) to 1.24 X 10(-3) M) inhibits spontaneous motility of ascending colon of the rat. Resting tension was not affected. At concentrations between 2.07 X 10(-5) to 1.24 X 10(-3) M it inhibited in a dose-dependent manner the contractions induced by maximal doses of acetylcholine. Higher doses produced a very marked inhibition that was attributable to acidification of the medium. The inhibiting effect was more intense when the incubation medium contained an excess of calcium (3.6 and 4.3 mM) or theobromine (10(-4) and 10(-3) M). This inhibiting effect tended to be smaller in the presence of low calcium (0.6 and 1.0 mM) or verapamil (3 X 10(-8) and 10(-7) M).