Long-term protection of ischaemic myocardium by nitroglycerin ointment

To assess whether the reduction in ischaemic injury during acute myocardial infarction induced by nitroglycerin (NTG) results in a decrease in tissue necrosis, 96 rats were assigned to two groups. The first group (n = 34) was sham-operated. The second group of 62 rats was randomised in a ratio of 2:1 into control (n = 43) and treated (n = 19) subgroups following coronary artery occlusion. Treated animals received an application of 2% NTG ointment every 8 h immediately post-occlusion. All rats were killed 48 h after coronary artery occlusion and total creatine kinase activity (CK) of the left ventricle (LV) was measured. Infarct size calculated by CK depletion was 65.2 +/- 14.3% (mean +/- SD) of LV in control rats, and 51.6 +/- 14.0% of LV in NTG-treated (p less than 0.02). In a further series of 46 rats with coronary occlusion, the area of infarcted myocardium 21 days post-occlusion was assessed by planimetry on histological sections. In rats with control occlusion (n = 22), the extent of infarction was 30.6 +/- 4.8% of LV, and in NTG-treated rats (n = 24) it was 16.2 +/- 5.8% of LV (p less than 0.001). The amount of scar tissue in the infarcted myocardium 21 days post-occlusion was also determined by measuring LV hydroxyproline and collagen content in an additional 32 rats randomly assigned to a control (n = 11), a NTG-treated (n = 9) and a sham-operated group (n = 12).(ABSTRACT TRUNCATED AT 250 WORDS)