| RESEARCH PAPER
|Year : 1999 | Volume
| Issue : 3 | Page : 190-194
Some effects of pentazocine on skeletal muscle and its transmission
SA Igwe, G Onuaguluchi
Objectives: To study the effect of pentazocine on some selected skeletal muscle preparations and the antagonism of its effect by some neuromuscular blocking agents.
Methods: In isolated rectus abdominis muscle preparation of the toad ( Buffo regularis) the response of acetylcholine and pentazocine were obtained in the absence and in the presence of d-tubocurarine and the potency ratio was calculated. The effect of pentazocine on the hemidiaphragm response to electrical stimulation of phrenic nerve was studied in Bulbring's isolated phrenric nerve diaphragm preparation. The antinicotinic activity of pentazocine was also studied in the day-old chick.
Results: Pentazocine potentiates acetylcholine-induced contraction of the toad rectus muscle and per.sc induces contraction of the toad rectus muscle which was antagonised by tubocurarine in a noncompetitive manner giving a potency ratio of acetylcholine: pentazocine of 1:2; impairs indirectly evoked contractions of the rat diaphragm where tubocurarine was at least 3 times more potent than pentazocine produces ataxia in day old chicks and antagonises tubocurarine and suxamethonium induced paralysis in vivo.
Conclusion: Pentazocine, like other opioids, acts directly on the skeletal muscle to impair its functions and exerts antagonism against selected neuromuscular blocking agents.
S A Igwe