[Effect of berberine, glaucine, stephaglabrine and sanguiritrine on neuromuscular transmission]

Natural alkaloid drugs, glaucine, stephaglabrine and sanguiritrine, are shown to affect the synaptic transmission in a fairly complicated manner and seem to involve several different mechanisms of action. These substances as well as berberine reduce amplitude of the spontaneous miniature end plate potentials in a frog neuromuscular junction. At low concentrations all the mentioned alkaloids diminish frequency of miniature potentials, but increase it when their concentration exceeds a certain value. Sanguiritrine is the most active in this respect (nearly a 100-fold increase), that is probably associated with its uncoupling effect on the mitochondrial oxidative phosphorylation. Sanguiritrine and stephaglabrine both cause repeated muscle contractions, that is in line with their anti-cholinesterase properties. Glaucine provokes only muscle contracture if present at relatively high concentration.