RESUMO
OBJECTIVE: To explore the effects of Rho-kinase inhibitor on cardiac hypertrophy of left ventricle in spontaneously hypertensive rats (SHR). METHODS: SHRs (n = 30) were randomly divided into 5 groups (n = 6 each): SHR control group, 5 mg/kg fasudil group (SHRL), 10 mg/kg fasudil group (SHRM), 20 mg/kg fasudil group (SHRH) and nifedipine group (XBDP, 10 mg/kg). Six male Wistar-Kyoto rats were selected as normal control group (WKY group). Systolic blood pressure (SBP) was measured before and after treatment every 2 weeks. The hypertrophic parameters of left ventricular weight index (LVWI) and cardiomyocyte transverse diameter (TDM) were measured. In addition, the expression levels of Rho kinase mRNA and protein in cardiomyocytes were observed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. RESULTS: The levels of LVWI and TDM in WKY group were significantly lower than those in SHR control group [(2.98 ± 0.05) vs (3.16 ± 0.08) mg/g, (18.18 ± 0.75) vs (21.32 ± 1.25) µm, P < 0.01]. After 8 weeks, the levels of LVWI and TDM in three fasudil groups were markedly lower than those in SHR control group [SHRL group: (3.12 ± 0.05) mg/g, SHRM group: (3.10 ± 0.07) mg/g, SHRH group: (3.08 ± 0.09) mg/g vs SHR control group: (3.16 ± 0.08) mg/g, SHRL group: (20.11 ± 1.15) µm, SHRM group: (19.63 ± 1.62) µm, SHRH group: (18.91 ± 1.05) µm vs SHR control group: (21.32 ± 1.25) µm, P < 0.05 or P < 0.01]. But the levels of LVWI and TDM were not different between SHR control and XBDP groups [(3.14 ± 0.08) mg/g,(21.42 ± 1.23) µm, P > 0.05]. Compared with SHR control group, the expression of Rho kinase mRNA and protein in cardiomyocytes significantly decreased in three fasudil groups [SHRL group mRNA: (0.45 ± 0.08), SHRM group mRNA: (0.37 ± 0.07), SHRH group mRNA: (0.32 ± 0.07) vs SHR control group mRNA: (0.63 ± 0.07), SHRL group protein: 0.78 ± 0.11), SHRM group protein: (0.73 ± 0.10), SHRH group protein: (0.68 ± 0.10) vs SHR control group protein: (0.90 ± 0.1), P < 0.05 or P < 0.01], but showed no obvious change in XBDP group [mRNA: (0.56 ± 0.07), protein: (0.85 ± 0.10), P > 0.05]. CONCLUSIONS: Rho kinase inhibitor may significantly down-regulate the expression of Rho kinase in cardiomyocytes of SHR. The mechanism is probably due to the favorable effects of Rho kinase inhibitor in the prevention of cardiac hypertrophy of left ventricle.