Inhibitory Effect of Ldegrees Cal Anesthetics on Voltage-Dependent Calcium Current; Relationship Between Potency and Hydrophobicity / 대한마취과학회지

BACKGROUND: The primary mode of conduction bldegrees Ckade by ldegrees Cal anesthetics degrees Ccurs through the inhibition of voltage-dependent sodium current and, inhibitory potency of ldegrees Cal anesthetics are correlated with their hydrophobicity, expressed as degrees Ctanol/buffer partition coefficients(PC). The homologous structural bidegrees Chemistry and analogous physiology of voltage-dependent sodium and calcium channels prompted us to examine the relationship between potency of various ldegrees Cal anesthetics for the inhibition of voltage-dependent calcium channels(VDCC) and their PC values. METHODS: Whole cell patch clamp recordings were made from acutely dissdegrees Ciated rat dorsal root ganglion neurons, and voltage dependent calcium current(ICa) was evoked by depolarizing pulse. The concentrations of various ldegrees Cal anesthetics(bupivacaine, liddegrees Caine, prildegrees Caine, prdegrees Caine, tetracaine) that bldegrees Ck 50% of the control ICa(IC50) were calculated from dose-response curves. The relationship between IC50 and PC values of various ldegrees Cal anesthetics were investigated. RESULTS: Ldegrees Cal anesthetics inhibited ICa with neglegible effect on the current- voltage relatonship. IC50 values of tetracaine, bupivacaine, liddegrees Caine, prildegrees Caine and prdegrees Caine were 98, 142, 2710, 10400, 16900 uM respectively, and linear regression of the plot of log(IC50) against log(PC) was statistically significant (p<0.001). CONCLUSIONS: It is speculated that inhibitory effects of ldegrees Cal anesthetics on the VDCC when used in epidural and spinal anesthesia may contribute to their analgesic and anesthetic actions. Inhibitory potency of ldegrees Cal anesthetics on the VDCC, as for voltage-dependent sodium channels, was correlated with their hydrophobicity.

The Prophylactic Effect of Propofol on the Side Effects of Intrathecal Morphine / 대한마취과학회지

While intrathecal morphine in small doses has been effective in controlling postoperative pain, many patients have been suffered from the side effects. In recent studies, it has been suggested that small dose of propofol can attenuate these side effects of intrathecal morphine. We have studied the effect of propofol and tried to find the optimum dose that can reduce side effects of intrathecal morphine. Sixty patients of ASA class 1 scheduled for anorectal surgery were allocated randomly to receive either a bolus dose of propofol 0.5 mg/kg followed by an infusion of 1 mg/kg/24hr(group Pl) or 2 mg/kg/24hr(group P2) and no bolus dose followed by 1,000 ml 5% dextrose water(control group). In this study, postoperartive sedation, nausea, vomiting, pruritus and urinary retention were evaluated immediate postoperatively, 12 hour, 24 hour and 48 hour after spinal anesthesia using 1% tetracaine 5 mg with 10% dextrose water 5 ml and morphine 0.3 mg. As time passed, all the complications subsided significantly. However, there was no significant difference among 3 groups except pruritus. The incidence of pruritus was lower in the group P1 and group P2(80%, 50% respectively) than the control group(90%). In the 12 hour-after evaluation, there was no patient of grade 3 pruritus in the group P2 but 5 patients in the control group(p<0.001) and 3 patients in the group Pl had itching(p<0.05). The higher doses of propofol, the greater sedative effect observed. However, there was no clinicaliy serious problem (e.g. respiratory depression, deep sedation). In conclusion, we recommend that an adequate infusion dose of propofol for reducing the incidence and severity of pruritus is 2 mg/kg/24hr.