The Effects of Some Anaesthetics on the Electrocardiograms of Guinea Pigs


Abstract: This study was carried out to observe the effects on electrocardiography of using droperidol-fentanyl and ketamine-xylazine combinations, urethane and pentothal sodium as anaesthetic doses. In this study, thirty-five 4-5 months-old quinea pigs of both sexes weighing 540-600 g were used. The quinea pigs were divided equally into 5 groups. The first group was used as the control group and nothing was given to this group. The combination of droperidol (20 mg/ml)-fentanyl (0.4 mg/ml) in a dose of 0.8 ml/kg b.wt., was intramuscularly injected into the second group. The combination of ketamine-xylazine was intramuscularly injected into the third group in doses of 0.8 ml/kg and 35 mg/kg b.wt. and 0.2 mg/kg b.wt. respectively. The solutions of 30% urethane for the forth group and 2.5% pentothal sodium for the fifth group were intraperitoneally injected in doses of 0.5 g/kg b.wt. and 2.5 mg/kg b.w. respectively. Electrocardiograms were recorded on bipolar extremity leads (I, II and III). The quantitative measurements namely: heart rates, amplitudes of the P, R, S and T waves, the durations of the P and T waves, the QRS complex and finally the durations of the PR and QT intervals were evaluated from lead II. In addition the electrical axis of the QRS complex was obtained from leads I and III. The duration of the P wave was prolonged while its amplitude was decreased with the combination of ketamine-xylazine. However, any effects on the P wave caused by the others were not observed. All the anaesthetics except pentobarbiton sodium prolonged the duration of the PR and QT interval and decreased the heart rates. In contrast to this, all decreased the duration of the QRS complex, but the decrease caused by urethane was not signifnanty different from that of the control group. One of the observed results was that the electrical axis of the QRS complex was not affected by the anaesthetics. As a conclusion, it was observed that the combinations of droperidol-fentonyl and ketamine-xylazine had clear effects but urethane and pentothal had only limited effects on the ECG.

Keywords: Guinea pig, ECG, droperidol-fentanyl, ketamine-xylazine, ürethane, pentothal sodium

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