Background:
Thymol is widely used as a general antiseptic and antioxidant compound in the medical practice and industry, and also as a stabilizer to several therapeutic agents, including halothane. thus intoxication with thymol may occur in case of ingestion or improper anesthesia. in the present study, therefore, concentration-dependent effects of thymol (30-600 micro-grams) were studied on calcium and potassium currents in enzymatically isolated rat skeletal muscle fibers using the double vaseline gap voltage clamp technique.
Results:
Thymol suppressed both ca and k currents in a concentration-dependent manner, the ec50 values were 193 +/- 26 and 93 +/- 11 microm, with hill coefficients of 2.52 +/- 0.29 and 1.51 +/- 0.18, respectively. thymol had a biphasic effect on ca current kinetics: time to peak current and the time constant for inactivation increased at lower (100-200 microm) but decreased below their control values at higher (600 microm) concentrations. inactivation of k current was also significantly accelerated by thymol (200-300 microm). these effects of thymol developed rapidly and were partially reversible. in spite of the marked effects on the time-dependent properties, thymol caused no change in the current-voltage relationship of ca and k peak currents.
Conclusions:
Present results revealed marked suppression of ca and k currents in skeletal muscle, similar to results obtained previously in cardiac cells. furthermore, it is possible that part of the suppressive effects of halothane on ca and k currents, observed experimentally, may be attributed to the concomitant presence of thymol in the superfusate.