338
J. Magyar et al
Effect of thymol on cardiac cells
Although the concentration of thymol is relatively low
(0.01%) in the original halothane-thymol mixture, its
concentration may dramatically increase due to accumulation
of thymol in the vaporizer in case of improper use. In a
perioperative cardiac arrest registry performed in pediatric
patients two third of cases of cardiac arrest due to medication
was considered to be a consequence of application of
halothane (Morray et al., 2000). Indeed, halothane was
shown to block ICa and IK in guinea-pig ventricular myocytes
with little eect on IK1 (Hirota et al., 1989). Similar results
were obtained by Baum et al. (1994), where suppression of
ICa was associated with a 711 mV leftward shift of the
steady-state inactivation curve. Davies et al. (2000) found
halothane to depress Ito in rat ventricular cells. These eects
obtained with liquid halothane (containing also thymol)
resembles our present results with thymol, raising the
possibility that some of the cardiac eects ascribed previously
to halothane may probably be attributed to the concomitant
presence of thymol in the superfusate.
Financial support for the studies was obtained from grants to J.
Magyar and P.P. Nanasi and from the Hungarian Ministry of
Health (ETT-52/2000, ETT-244/2000), the Hungarian Ministry of
Education (FKFP-0243/2000) and Hungarian Research Fund
(OTKA-T037334).
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British Journal of Pharmacology vol 136 (2)