Effects of emulsified isoflurane on haemodynamics and cardiomyocyte apoptosis in rats with myocardial ischaemia

Abstract

1. It has been shown that inhaled isoflurane limits the size of myocardial infarcts. The aim of the present study was to examine the effects of emulsified isoflurane on cardiac function and myocardial apoptosis in an ischaemia model of myocardial injury. 2. In the first study, 48 rats were randomly allocated to six groups (n = 8 in each): control (saline); emulsified isoflurane (EIso) at 1, 2 or 4 mL/kg; 30% intralipid (vehicle for EIso); and sham operated. Rats received isovolumetric intravenous infusions for 30 min and then, 30 min after cessation of the infusion, 90 min coronary occlusion. Haemodynamics and myocardial infarct size were measured. In the second study, another 48 rats were randomized into six groups (n = 8 in each). After 90 min ischaemia, rats were killed for histopathological study, immunohistochemical evaluation and apoptosis measurement. 3. Pretreatment with 2 and 4 mL/kg EIso significantly attenuated decreases in left ventricular systolic pressure and dP/dt(max), and increases in left ventricular end-diastolic pressure and -dP/dp(max), and alleviated myocardial injury compared with the control, intralipid and 1 mL/kg EIso groups (P < 0.05). Infusion of 1 mL/kg EIso and intralipid had no effect on haemodynamics, infarct size or histological variables. 4. Expression of Bcl-2 was increased, whereas expression of Bax and caspase 3 was decreased, after preconditioning with 2 and 4 mL/kg EIso (P < 0.05). The apoptotic index in the 2 and 4 mL/kg Eiso-treated groups was reduced compared with that in the control and intralipid groups (P < 0.01). 5. In conclusion, EIso ameliorates cardiac dysfunction, attenuates myocardial damage and inhibits apoptosis after ischaemia, which may be attributed, in part, to diminished expression of apoptosis-related protein.