Inhibición de la hipertrofia ventricular izquierda, normalización de la respuesta contráctil cardíaca y estrés oxidativo en hipertensión experimental

摘要

Background and objectives: Left ventricular hypertrophy secondary to hypertension has been perceived as a protective mechanism to reduce wall stress and prevent heart failure. However, its presence is paradoxically associated with increased cardiovascular morbidity and mortality The aim of this study was to evaluate whether chronic antihypertensive treatment inhibits the development of left ventricular hypertrophy and normalize the reverting impaired cardiac beta-adrenergic response, and its possible association with changes in myocardial oxidative metabolism. Methods: Spontaneously hypertensive male rats (SHR, 2 months old) were divided into groups (n grupo= 18) according to (mg/ group kg, p.o): losartan 30 (L), hydralazine-11 (H), rosuvastatin 10 (R), carvedilol 20 (C), and water (control treatment). The control hypertension group consisted of 18 normotensive rats (Wistar-Kyoto, WKY). Systolic blood pressure (SBP) (plethysmography in awake animals) and body weight (BW) were measured periodically. The animals were sacrificed at 16 months and 50% of the hearts were mounted in a Langendorff system to measure contractility before and after beta-adrenergic stimulation [isoproterenol (Iso): 10-9 M, 10-7 M, and 10-5 M]. In the remaining hearts left ventricular weight (LVW) was measured and normalized by B W. Immunohistochemical expression of thioredoxin 1 (Trx-1), peroxyredoxin 2 (Prx-2) and glutaredoxin 3 (Grx-3) (antioxidant indicators) was quantified. Results: Body weight was similar in all groups. Systolic blood pressure (mm Hg) was 154 ± 3 (L), 137 ± 1 (H), 190 ± 3 (R)**, 206 ± 3 (SHR)*, 183 ± 1 (C)**, and 141 ± 1 (WKY) (* p < 0.05 vs. L, H, WKY, ** p < 0.05 vs. L, H, WKY, SHR). LVW/BW was higher in SHR and R (p < 0.05) compared with L, H, C and WKY. In C, there was no correlation between hypertension and left ventricular hypertrophy. SHR, R and C evidenced baseline contractile depression vs. L, H and WKY. The response to 10-5 M Iso was similar in WKY and L, and reduced in C, H, R and SHR. The expression of Trx-1, Prx-2 and Grx-3 increased in C, H, R and L (average increase: 1.5-2 times; p < 0.01 vs. SHR and WKY). Conclusions: Treatment with losartan, hydralazine, and carvedilol prevented the development of left ventricular hypertrophy. Losartan normalized the response to isoproterenol in SHR. Additional factors might participate in the development of left ventricular hypertrophy with impaired inotropic response to beta-adrenergic stimulation in hypertension. The increased ex-pression of thioredoxins as a result of antihypertensive treatment suggests an additional benefit, increasing the antioxidant response against oxidative stress in hypertension.