[The effects of heptaminol chlorhydrate on neuromuscular transmission].

6-Amino-2-methyl-2-heptanol chlorhydrate, heptaminol chlorhydrate, blocks the response to indirect stimulation of the mouse diaphragm in vitro. This effect is due to a dose-dependent pre- and post-synaptic block of neuromuscular transmission starting at 1 mM heptaminol (HEPT). The complete block of neuromuscular transmission occurs at 10 mM. At 2 mM, the decrease in quantal size is more significant in the presence of d-tubocurarine than when the extracellular calcium is lowered. At this concentration, heptaminol also prolongs the depolarization time of the motor end plate potential. Slightly higher concentrations of heptaminol produce a decrease in quantal content. This latter effect is associated with an increase in synaptic delay.