Tetanic fade during neuromuscular blockade produced by atracurium in the rat diaphragm preparation.

ABSTRACT

In the present investigation, we studied and measured the phenomenon of tetanic fade and peak tetanic tension depression in the rat diaphragm preparation in the presence of a blocking concentration of atracurium (e.g., 10 mumol.l-1). Atracurium (10 mumol.l-1) produced a pronounced tetanic fade (i.e., 47-69% reduction of total sustained tetanic tension) at a time (15 s) when it reduced the peak tetanic tension by only 25%. The time course for total tetanic fade was 30-35 s, whereas the time taken for complete peak tetanic tension depression was 3-3.5 min, suggesting that the two effects were produced via different mechanisms, involving presynaptic and postsynaptic mechanism. It was concluded that atracurium produces a profound tetanic fade, with respect to its effect on twitch or tetanic tension, suggesting that the drug is a potent neuromuscular blocker, with rapid onset of blockade.