Abstract: AIM: To investigate the effects of hydro-chlorothiazide and indapamide on cardiac remodeling and the expression of endothelial nitric oxide synthase (eNOS) in spontaneous hypertensive rats (SHR).METHODS: Fifteen female SHRs were randomly divided into 3 groups (n =5):control group, hydrochlorothiazide(HCTZ, 10 mg·kg^-1 ·d^-1)group and indapamide (IND, 0.625 mg·kg^-1 ·d^-1)group.Systolic blood pressure (SBP)of the rats in each group was measured at pretreatment and each week during the study.Four weeks later, rats were sacrificed and the ratio of heart weight to body weight was calculated, collagen deposition in the heart was deter-mined histochemically using Sirius red staining, and eNOS protein expression of the heart was determined by Western blot.RESULTS: Both HCTZ and IND reduced the SBP of SHRs significantly (P<0.05).The drug group showed normal myocardium structure as compared with control rats which showed myocardium cell hypertro-phy, derangement, interstitial proliferation and mass col-lagen deposition.HCTZ and IND increased the eNOS ex-pression significantly.CONCLUSION: Both HCTZ and IND can protect the heart by reversing cardiac remodel-ing, upregulate the eNOS expression and reduce collagen deposition.

Key words: hydrochlorothiazide, indapamide, spon-taneous hypertensive rats, left ventricular hypertrophy, endothelial nitric oxide synthase