Abstract
Background: In a series of experiments, we have shown that the doxapram HCl inhibited the cardiac conduction system under urethane anesthesia in the adult Wister rats. The purpose of the present study is to evaluate the effect of doxapram HCl on the cardiac conduction system under sevoflurane anesthesia which has been clinically used. Materials and Methods: ECG and respiratory movements were recorded by Biopac MP-35 system with a sampling frequency of 1000 Hz. The doxapram HCl (0.3-10 mg/kg) was repeatedly injected into the right femoral vein with an appropriate interval in each animal. The effect of the drug was evaluated by measuring RR, PQ and QT intervals of ECG at 3 min after administration of the drug. Results: 1) RR interval was dose-dependently prolonged with administration of the doxapram HCl. Administration of 10 mg/kg of the drug showed significant prolongation (0.168±0.012 sec) as compared with the control (0.159±0.011 sec). 2) PQ interval showed no change in any dose of the doxapram HCl. 3) QTc value was significantly prolonged by administration of the drug (0.147±0.015 sec with 3.0 mg/kg and 0.154±0.018 sec with 10 mg/kg) as compared with the control (0.138±0.011 sec). Conclusion: We should carefully pay an attention to QT prolongation when we use the doxapram HCl for an accelerant of respiration under the sevoflurane anesthesia. [J Physiol Sci. 2008;58 Suppl:S178]
