The Effects of Magnesium Pretreatment on Vecuronium - Induced Neuromuscular Blockade in Cats with Acute Renal Failure

Jung, Hyun Jung; Lee, Choon Soo; Shin, Yang Sik; Yoon, Il Yong

Abstract

The magnesium-induced neuromuscular blocking effect alone and the change of vecuronium- induced neuromuscular blocking effect by magnesium pretreatment were evaluated in twelve cats weighing 2.0-4.0 kg, assigned randomly into two groups; 6 cats with bilateral renal pedicle double ligation (group II), and the others with the sham operation (group I). Pharmacodynamic studies were done using a sciatic nerve-anterior tibialis muscle preparation. Plasma magnesium concentrations after magnesium administration in both groups were significantly higher than those prior to magnesium administration. However, there was no significant difference in increased magnesium concentrations between the two groups. The median effective dose of magnesium obtained by cumulative dose-response study, were 33.4+/-11.9 mg/kg, 24.9+/-12.0 mg/kg in both groups, respectively. The ED(50) of vecuronium after magnesium pretreatment in group I and II were 11.25+/-3.39 ug/kg and 11.26+/-2.54 ug/kg respectively. The duration of magnesium-induced neuromuscular block in group II (12.10+/-4.53 min) was not different from that of group I (8.37+/-4.25 min). The recovery index of magnesium-induced neuromuscular block in group II (3.98+/-1.51 min) was significantly prolonged when compared to that of group I (2.08+/-1.32 min). The duration of vecuronium-induced neuromuscular block with magnesium pretreatment in group II (22.39+/-11.41 min) was not significantly prolonged from that of group I (21.18+/-9.81 min). Also, the recovery index of vecuronium in group II (6.78+/-1.79 min) was not significantly different from that of group I (7.19+/-4.62 min). These results suggested that magnesium by itself had neuromuscular blocking effect, which was considered as one thousand potency of vecuronium As compared with normal renal function, there was no significant increase of plasma concentration of magnesium by acute renal failure after magnesium administration. Also, vecuronium-induced neuromuscular block with magnesium pretreatment was potentiated as much as three times in the both. groups equally. However, vecuronium-induced neuromuscular blocking effect was not changed by acute renal failure, as compared with normal renal function.