Effect of esmolol on oxidant status and antioxidant activity in acute myocardial infarction.

AIMS AND OBJECTIVES: The role of oxygen free radicals in reperfusion injury to the heart in myocardial infarction (MI) has been postulated. In this study, the clinical and antioxidant effects of esmolol, an ultra-short acting beta blocker in patients of acute MI was studied. MATERIAL AND METHODS: This was a randomized, double-blind, controlled, prospective study. Total 30 patients with acute MI were included. All patients were thrombolysed with streptokinase. Fifteen of these patients were randomly selected to receive esmolol while other 15 patients served as controls. The parameters compared at 0, 2 and 24 hours between the esmolol group and the controls were--malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPX). RESULTS: Patients with MI had 5.16 times higher MDA level at 0 hours (20.34 +/- 6.12 nmol/ml vs. 3.94 +/- 0.70 nmol/ml, p < 0.0001) than MDA level in normal healthy population. At 2 hours, patients with MI had 5.71 times higher MDA level compared to normal healthy population (22.51 +/- 5.51 nmol/ml vs. 3.94 +/- 0.70 nmol/ml, p < 0.0001). A statistically significant difference in MDA levels at 2 and 24 hours was observed in MI patients given esmolol (mean change 2.06 +/- 5.39 nmol/ml vs. -4.47 +/- 6.93 nmol/ml, p = 0.009). Esmolol infusion also caused significant difference in GPX level at 2 hours compared to controls (23.79 + 14.68 U/gm Hb vs 38.3 +/- 8.95 U/gm Hb, p = 0.003). CONCLUSION: Free radical levels are raised in patients with MI which may contribute to reperfusion injury. The antioxidant action of esmolol was clearly observed by significant difference in MDA level and GPX sparing effect. Large scale clinical trials may establish conclusively role of beta blockers as antioxidants as adjuvant to thrombolytic therapy in MI.

Effects of exogenous vitamin E supplementation on the levels of oxidants and antioxidants in chronic obstructive pulmonary disease.

Oxidative stress has been recognized as a central feature of smoke induced chronic obstructive pulmonary disease (COPD). Imbalance between oxidant and antioxidant enzymes is also an established fact in these patients. But studies in regard to stable COPD patients and effect of vitamin E supplementation are lacking. Thirty patients with COPD were included in the study. Their baseline clinical examination, spirometry, plasma malondialdehyde (MDA), alpha-tocopherol and red blood cell superoxide dismutase (SOD) levels were mea sured. Twenty healthy non-smokers who were matched for age and sex served as controls. All the above parameters were repeated after 12 weeks of supplementation with 400 IU of vitamin E daily. The mean malondialdehyde levels in the patients at baseline were higher than controls (5.91 +/- 1.23 nmol/ml vs 4.55 +/- 1.51 nmol/ml, P = 0 001), so also was plasma alpha-tocopherol levels (P < 0 001), while SOD levels were lower in the patients compared to controls (1692 +/- 259 units g/Hb vs 2451 +/- 131 units g/Hb, P < 0 001). Exogenous vitamin E (400 IU per day) supplementation did not bring about any significant change in plasma alpha-tocopherol and SOD levels. The Pearson s co-efficient of correlation between the levels of MDA, vitamin E, SOD; and spirometric measurements were not significant either on day 1 or after 12 weeks of vitamin E supplementation. The present study shows that initially the plasma lipid peroxide (MDA) levels are high and antioxidants (alpha-tocopherol and SOD) are low in patients with COPD. Exogenous supplementation with vitamin E does not have any significant effect on the spirometric measurements though it brings down the levels of MDA showing attenuation of further damage. However, inclusion of larger number of patients and supple mentation with vitamin E for longer periods may throw more light on free radical injury and protective effects of antioxidants.