Myocardial infarct size reduction by single high dose or repeated low dose vitamin E supplementation in rabbits

Abstract

Objective: To determine whether myocardial infarct size in rabbits could be reduced by pretreatment with vitamin E, either as a dietary supplement over 10 days or as a single oral dose either 24 or 72 h before coronary artery occlusion and reperfusion.

Design: Control and treated rabbits underwent 3 h of coronary artery ligation and 6 h of reperfusion. Region at risk was defined by colloidal carbon and necrosis by triphenyl tetrazolium chloride and light microscopy. Percentage necrosis of the region at risk was determined by planimetry of gross tissue sections by a blinded observer. Analysis of variance and Scheffé's F test compared results.

Setting: The animal research facilities of the Toronto Hospital (General Division).

Animals: Adult New Zealand rabbits.

Interventions: Controls (n = 8) received standard feed; treated groups (n = 8) were given supplemental vitamin E doses of 2000 IU 24 h preoperation (group 24-E), 2000 IU 72 h preoperation (group 72-E) or 200 IU.day-1 for 10 days preoperation (group Lo-E, n = 8).

Main results: Percentage necrosis of the region at risk was: control mean, 76.2 +/- 13.0 (mean +/- SD); Lo-E group, 21.8 +/- 10.6; 24-E group, 67.6 +/- 15.1; 72-E group, 47.1 +/- 21.5. Myocardial infarct size was reduced significantly (P < 0.05) versus control in groups Lo-E and 72-E, but not in group 24-E.

Conclusions: Myocardial infarct size in rabbits can be reduced by 10 days of supplemental dietary vitamin E or a single oral dose of vitamin E 72 h before ischemia. The current results suggest possible clinical potential for oral vitamin E to be used as prophylaxis against myocardial ischemia and reperfusion injury.