ABSENCE OF SKELETAL-MUSCLE LESIONS AFTER EXPERIMENTAL RESTRAINT STRESS-INDUCED BY PANCURONIUM IN NORMAL AND STRESS-SUSCEPTIBLE PIGS

Stress-susceptible (SS) pigs develop rhabdomyolysis and increased seru m levels of muscle enzymes after a 12 min experimental stress induced by the depolarizing myorelaxant succinylcholine. It is suspected that not only the stress situation but also succinylcholine itself contribu tes to the skeletal muscle lesions. This experiment was performed to s tudy whether rhabdomyolysis occurs after restraint stress when succiny lcholine was replaced by the nondepolarizing myorelaxant pancuronium. Four normal and four SS pigs were subjected to restraint stress by int ravenous injection of pancuronium. The neuromuscular block was reverse d after 12 min by neostigmine. The animals were necropsied approximate ly 48 h after stress and 24 skeletal muscle groups were examined patho logically. The severity of acute myofibre lesions were graded, and the results were compared with the results from normal and SS pigs which had been subjected to restraint stress induced by succinylcholine. The serum levels of creatine kinase (CK) and aspartate aminotransferase ( ASAT) stayed at the base line level after the stress. The scores for m uscle lesions were significantly lower, both in normal and SS pigs, th an after restraint stress induced by succinylcholine indicating no rha bdomyolysis after restraint stress induced by pancuronium. Thus succin ylcholine is synergistic with stress, exacerbating its effect on skele tal muscle in SS pigs.