To explore the effect of dietary copper supplementation on the expression of myocardial matrix metalloproteinase 2 (MMP-2) and hemodynamics after myocardial infarction (MI) in rats.

Forty adult male Sprague-Dawley rats, aged 6-8 weeks and weighing (260±15)g, were selected. Rats were divided into a sham operation control group (control group, n=10), an MI group (n=15), and a dietary copper supplementation group (MI-Cu group, n=15) using the method of random number table. MI models were made in MI group and MI-Cu group, and control group performed sham MI operation. The MI-Cu group was given an adequate copper diet (20 mg/kg), and the control group and the MI group were given a copper diet (6 mg/kg). After 4 weeks of careful feeding, the pre-and post-operative ST segment deviation values of rats was exported from the electrophysiological instrument. The left ventricular end diastolic pressure (LVDEP), left ventricular systolic pressure (SYS), mean arterial pressure (MBP), maximal rate of increase of left ventricular pressure (+ LVdp/dtmax), and maximal rate of decrease of left ventricular pressure (-LVdp/dtmax) were detected. The pathological changes after MI in rats were observed under a microscope after Masson staining. The expression of myocardial MMP-2 in rats was detected by enzyme linked immunosorbent assay. Paired t-test was used to compare the ST segment deviation values before and after surgery. One-way analysis of variance and LSD-t test were used to compare the hemodynamic indexes and MMP-2 expression levels between groups.

After the model was established, 8 rats survived in the control group, 8 rats survived in the MI group, and 10 rats survived in the MI-Cu group. The ST segment deviation value of the electrocardiogram in the MI group and MI-Cu group after surgery [(33.00±3.24)mV] was significantly higher than that before surgery [(2.90±1.14)mV] (t=-44.303, P<0.01). LVDEP in the MI-Cu group [(24.10±0.75)mmHg, 1 mmHg=0.133 kPa] was significantly lower than that in the MI group [(32.49±1.82)mmHg] (t=-15.93, P<0.01). LVDEP in the MI group and the MI-Cu group were significantly higher than that in the control group [(1.41±0.09)mmHg] (t=55.93, 43.03, all P<0.001). SYS [(75.18±2.33)mmHg], MBP [(62.54±1.86)mmHg], + LVdp/dtmax[(2 592.00±192.52)mmHg/s], and -LVdp/dtmax [(2 188.00±286.15)mmHg/s] in the MI-Cu group were significantly higher than those in the MI group [(65.20±1.63)mmHg, (55.90±1.66)mmHg, (1 722.5±162.28)mmHg/s, (1 643.75±101.55)mmHg/s](t=6.12, 4.41, 10.36, 5.76, all P<0.01). SYS, MBP, + LVdp/dtmax, and -LVdp/dtmax in the MI group and MI-Cu group were significantly lower than those in the control group [(112.31±5.42)mmHg, (104.19±5.10)mmHg, (5 839.75±170.21)mmHg/s, (4 693.75±120.70)mmHg/s] (t=-27.35, 30.40, -46.52, -30.65, -22.72, -27.64, -38.68, -26.54, all P<0.01). In the control group, the left ventricular myocardial thickness was uniform and the ventricular cavity was normal. In the MI group and MI-Cu group, the MI area of the left ventricle was significantly thinner, and the collagen fibers were blue. The pathological damage of ventricular myocardium in the MI-Cu group was improved to some extent compared with the MI group. The expression level of MMP-2 in the MI-Cu group[(116.12±14.33)μg/L] was significantly lower than that in the MI group [(147.27±1.79) μg/L] (t=-5.37, P<0.01). The expression levels of MMP-2 in the MI group and MI-Cu group were significantly higher than that in the control group [(83.93±9.34)μg/L] (t=10.53, 5.73, all P<0.01).

Dietary copper supplementation can inhibit the expression level of myocardial MMP-2, improve the hemodynamic indexes of the heart after MI in rats, and reduce myocardial pathological damage to a certain extent.