Objective: To study the effects of hyperhomocysteinemia on cardiac remodeling and systolic function.
Methods: Twenty-four Wistar rats were divided randomly into experiment and control group. 12 rats of experiment group were bred with 1 g/(kg.d) L-methionine. After 4 weeks, 6 of them were killed (HHcy), others were continuously bred with normal diet for 4 weeks (Quit hcy, QHcy). Twelve rats of control group with normal diet for 4 and 8 weeks. The plasma Hcy concentrations were measured by immuno-fluorescence technique. Left ventricular structure and systolic function were assessed by echocardiography. The cardiac morphology and collagen were studied by optical microscopy and image analysis system after hematoxylin eosin-staining and picrosirius red-staining. Immuno-histochemistry for actin-smooth muscle and factor VIII-related antigen was performed to identify changes in cardiac smaller arteriolar and microvascular numbers.
Results: The plasma Hcy concentration was (106.19+/-19.75) micromol/L in HHcy, (6.52+/-0.94) micromol/L in QHcy and (4.90+/-0.10) micromol/L in the control. Left ventricular systolic function was decreased 10.7% in HHcy. Left ventricular wall strain and cardiac smaller arteriolar wall thickness were increased by 62.1% and 2.9 fold in HHcy, 27.1% and 2.4 fold in QHcy as compared with the control. Cardiomyocyte diameter was not changed in HHcy and increased by 15.4% in QHcy as compared with the control. Microvascular number was decreased by 45.9% in HHcy as compared with the control, but smaller arteriolar number did not differ among the groups. Left ventricular systolic function and microvascular number resumed in QHcy. Interstitial and perivascular collagen deposition was significantly increased in HHcy and QHcy.
Conclusion: Hyperhomocysteinemia may increase cardiomyocyte diameter, cardiac smaller arteriolar wall thickness and left ventricular wall strain; decrease microvascular number; induce interstitial and perivascular collagen deposition, directly and indirectly affect on cardiac remodeling and systolic function. The cardiac remodeling couldn't resume completely with plasma Hcy concentration being decreased.