NOTES ON THE PHARMACOLOGY OF THE HEARTS OF ARIOLIMAX COLUMBIANUS AND ASTACUS TROWBRIDGEI

Abstract

The effects of acetylcholine, atropine, eserine and nicotine on the isolated ventricle of A. columbianus were studied. Acetylcholine inhibited the slug ventricle at concs. as low as 1:10,000,000. Eserine potentiated the effects of acetylcholine and atropine failed to abolish its effects such as was shown in other mollusks. Nicotine first showed its effects at concs. of 1:7000 and these effects were similar to those of acetyl choline on the frequency but not on the amplitude. As far as the pacemaker was concerned, the effect of nicotine and acetylcholine were similar and additive. Preliminary tests were run on the in situ heart of A. trowbridgei with the above drugs and adrenaline. Acetylcholine increased the frequency and amplitude of the heart at a conc. as low as 1:10,000,000,000. Its action was blocked by atropin. Eserine alone increased the frequency of the heart. Nicotine at concs. of 1:10,000 increased the amplitude and decreased the frequency. Tests with adrenaline showed that this compound increased the frequency and amplitude but that the amplitude effect was irreversible. The heart responded to adrenaline 1:1,000,000.