[The action of non-depolarizing muscle relaxants on nerve terminal of motor endplate--relationship between run-down of endplate potentials and fading tension response].

The classical view of the neuromuscular transmission is that non-depolarizing muscle relaxants (MRs) enhance run-down of the endplate potentials (epps) by blocking pre-junctional nicotinic acetylcholine (ACh) receptors. Several recent investigations, when extended to pharmacology, have provided evidence to suggest the existence of other types of enhancement of run-down of epps by MRs; the enhancement of epps occurs without reduction of ACh release in the presence of MRs. It has been generally accepted that the enhancement of run-down of epps causes the tetanic fade of tension response. However, recent evidence indicates that run-down of epps does not always cause this wane in tension. The electrophysiological mechanism of run-down of epps at the neuromuscular junction and the relationship between that phenomenon and the extent of reduction of tension response are described based on a review of literature and our current investigations.