The effect of H2 receptor antagonists on neuromuscular transmission

We have reported that the H2 receptor antagonists, cimetidine and ranitidine, interfere with neuromuscular transmission on the isolated phrenic nerve--diaphragm preparation of the rat in vitro and we have suggested that the neuromuscular blockade produced could be ascribed to an action at presynaptic level by competing calcium ions unrelated to their specific effects on H2 histamine receptor: in fact, neuromuscular blockade was reversed by calcium and 4-aminopyridine but not by neostigmine or dimaprit. In the present study these results are confirmed in vivo on the sciatic nerve-gastrocnemius muscle preparation of the rat.