Effects of isoflurane on nitric oxide metabolism and oxidant status of guinea pig myocardium

Background: Volatile anesthetics (VAs) have been shown to enhance myocardia l recovery during reperfusion, the mechanism of which has not been clarifie d yet. It has been supposed that this effect of VAs may appear through anti oxidative mechanisms. Methods: Thirty guinea pigs were used in the study. There were three groups with 10 animals in each: I - control, II isoflurane+oxygen and III - oxyge n. Isoflurane (2.0% v/v) and oxygen (100%) mixture was given to the animals via a face mask in the isoflurane+oxygen group at the rate of 21 per min f or 30 min a day for three consecutive days. In the oxygen group, oxygen alo ne (100%) was given under the same conditions as in the isoflurane+oxygen g roup. At the end of the experiments, the animals were killed and their hear ts were removed. In the heart tissues, nitric oxide synthase (NOS) activity , nitric oxide (NO) pool (NO.+NO2-) and malondialdehyde (MDA) levels were m easured. Results: NOS activity was found to be higher and the NO pool lower in the i soflurane+oxygen group compared with those of control and oxygen groups. In the oxygen group, MDA level was found to be higher compared to the other g roups. There was, however, no significant difference between MDA levels of the control and isoflurane+oxygen groups. Conclusion: Our results suggest that isoflurane prevents peroxidation react ions in heart tissue, possibly by scavenging toxic oxygen radicals produced under hyperoxygenation conditions as occurs with general anesthesia.