BACKGROUND: Magnesium sulfate (MgSO4) has been used in the treatment of pre-eclampsia, hypertension and arrhythmia. This study was been conducted to evaluate the potency and time course of rocuronium-induced neuromuscular block after prolonged pretreatment with MgSO4 in rabbits. METHODS: Forty rabbits were randomly assigned to two groups; the control group: normal saline 0.1 ml/kg sq for 6 weeks; and the study group: 50% MgSO4 60 mg/kg sq for 6 weeks. The dose-response relationships of rocuronium were studied during thiopental anesthesia in twenty rabbits. Each group received rocuronium 40, 60 and 80microgram/kg rocuronium, respectively, and the time course of rocuronium, at 0.6 mg/kg, evaluated in the twenty rabbits in each group. RESULTS: The mean serum magnesium concentration were 2.3-2.6 and 3.3-3.9 mEq/L in the control and study groups, respectively (P < 0.001). The calculated ED50s for rocuronium were 52.7 and 61.2microgram/kg in the control and study groups, respectively (P < 0.05). The times after rocuronium administration until the 95% twitch recovery were 49.3 and 34.8 min in the control and study groups, respectively (P < 0.05). CONCLUSIONS: Rocuronium, following prolonged MgSO4 pretreatment had a decreased effect and short duration of action compared with the control, for which increased doses of nondepolarizing muscle relaxants would be required to obtain a similar effect.
Anesthesia ; Arrhythmias, Cardiac ; Hypertension ; Magnesium Sulfate* ; Magnesium* ; Neuromuscular Blockade* ; Pre-Eclampsia ; Rabbits* ; Thiopental

BACKGROUND: Pneumoperitoneum for a gynecologic laparoscopic surgery induces hemodynamic changes. We evaluated the effects of nicardipine on induction, maintenance, and recovery. METHODS: Thirty patients scheduled for gynecologic laparoscopic surgery were randomly allocated to two groups: control group (placebo group, n = 15), group N (nicardipine group, 10 microgram/kg followed by 0.5-2.0 microgram/kg/min). The systolic arterial pressure, mean arterial pressure, and heart rate were measured at preinduction, induction, intubation and 5, 10, 15, 20 min after insufflation. Loss of consciousness, induction dose, effective site concentration, propofol maintenance dose (the maintenance dose of propofol from intubation to end of anesthesia, PMD) were also measured. Propofol was titrated to maintain a bispectal index value of 40-60. RESULTS: There was a significant difference in PMD between two groups. The PMD of group N was significantaly less than group C. Nicardipine adminstration attenuated increase in the blood pressure, but did not affect on heart rates during CO2 insufflation. CONCLUSIONS: Co-administration of nicardipine was effective in attenuating the hemodynamic changes after pneumoperitoneum during gynecologic laparoscopic surgery, without changes of induction and recovery.
Anesthesia ; Arterial Pressure ; Blood Pressure ; Heart Rate ; Hemodynamics ; Humans ; Insufflation ; Intubation ; Laparoscopy* ; Nicardipine* ; Pneumoperitoneum ; Propofol ; Unconsciousness