We previously determined that residual left ventricular (LV) myocardium of middle‐aged rats had sex‐related differences in regional tissue properties 4 weeks after a large myocardial infarction (MI). However, the impact of such differences on cardiac performance remained unclear. Therefore, our current study aimed to elucidate whether sex‐related changes in MI‐induced myocardial remodeling can influence cardiac function. A similar‐sized MI was induced in 12‐month‐old male (M‐MI) and female (F‐MI) Sprague–Dawley rats by ligation of the left coronary artery. The cardiac function was monitored for 2 months after MI and then various LV parameters were compared between sexes. We found that although two sex groups had a similar pattern of MI‐induced decline in LV function, F‐MI rats had greater cardiac performance compared to M‐MI rats, considering the higher values of EF (39.9 ± 3.4% vs. 26.7 ± 7.7%, P < 0.05), SW index (40.4 ± 2.1 mmHg • mL/kg vs. 20.2 ± 3.3 mmHg • mL/kg, P < 0.001), and CI (139.2 ± 7.9 mL/min/kg vs. 74.9 ± 14.7 mL/min/kg, P < 0.01). The poorer pumping capacity in M‐MI hearts was associated with markedly reduced LV compliance and prolonged relaxation. On the tissue level, F‐MI rats revealed a higher, than in M‐MI rats, density of cardiac myocytes in the LV free wall (2383.8 ± 242.6 cells/mm2 vs. 1785.7 ± 55.9 cells/mm2, P < 0.05). The latter finding correlated with a lower density of apoptotic cardiac myocytes in residual LV myocardium of F‐MI rats (0.18 ± 0.08 cells/mm2 vs. 0.91 ± 0.30 cells/mm2 in males, P < 0.01). Thus, our data suggested that F‐MI rats had markedly attenuated decline in cardiac performance compared to males due to ability of female rats to better retain functionally favorable intrinsic myocardial properties.
Our previous study on post‐MI male and female middle‐aged rats has revealed that although both sexes had a similar scale of LV remodeling, the females showed a greater density of cardiac myocytes in the epimyocardium. However, the mechanism of this structural alteration, as well as its impact on LV function, remained unclear. Our current study was aimed at determining whether the sex‐specific difference in the density of cardiac myocytes is related to the rate of their death and whether it affects the cardiac performance in post‐MI rats. A large MI was induced in 12‐month‐old male (M‐MI) and female (F‐MI) Sprague‐Dawley rats by ligation of the left coronary artery. The cardiac function was monitored for two months post‐MI. At the end of the experiment, various LV parameters were compared between sexes. We found that although both groups had a similar pattern of decline in LV function, the F‐MI rats exhibited a less deteriorated cardiac performance compared to M‐MI rats, as indicated by the values of stroke volume (0.18±0.01 vs. 0.14±0.02 mL, P<0.05), ejection fraction (39.9±3.4 vs. 26.7±7.7 %, P<0.05) and cardiac output (57.8±3.1 vs. 44.6±8.7 mL/min, P<0.05). Moreover, the F‐MI rats displayed a higher density of cardiac myocytes in the epimyocardium than the males (2383.8±242.6 vs. 1785.7±55.9 cells/mm2, P<0.05). This was associated with a lower rate of myocyte apoptosis in the F‐MI rats (0.18±0.08 vs. 0.91±0.30 apoptotic cells/mm2, P<0.01). Thus, our data showed that the F‐MI rats had a better preserved LV function compared to M‐MI rats, and that this might be caused by an increased myocyte survival in females.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.