Bosentan attenuated norepinephrine-induced increases in ventricular weight, RNA to protein ratio, and specific hypertrophy marker mRNAs, suggesting ET-1 mediates ventricular hypertrophy in vivo.
Norepinephrine-induced ventricular hypertrophy (n=70)
Bosentan vs Sham operation and/or norepinephrine alone (100 mg/kg once daily)
Physical and molecular markers of ventricular hypertrophy (ventricular weight, RNA to protein ratio, mRNA expression)
BACKGROUND: Endothelin-1 (ET-1) has potent effects on cell growth and induces hypertrophy of cultured ventricular myocytes. Catecholamines increase expression of ET-1 mRNA by cultured myocytes. We investigated the role of endogenous ET-1 in catecholamine-induced hypertrophy in vivo by studying the effects of continuous norepinephrine infusion on physical and molecular markers of ventricular hypertrophy, ventricular and noncardiac expression of ET-1 mRNA, and the acute effects of bosentan, an orally active ETA and ETB receptor antagonist. METHODS AND RESULTS: Seventy male Sprague-Dawley rats (175 to 200 g) were divided into four groups: (1) sham-operated rats, (2) norepinephrine-infused rats (600 micrograms.kg-1.h-1 by subcutaneous osmotic pump, up to 7 days), (3) sham-operated rats given bosentan, and (4) norepinephrine-infused rats given bosentan. Bosentan (100 mg/kg once daily) was administered by gavage for 6 days starting 1 day before operation. Norepinephrine caused increases in absolute ventricular weight and ratios of ventricular weight to body weight and ventricular RNA to protein. Ventricular expression of mRNAs for atrial natriuretic factor, skeletal alpha-actin, and beta-myosin heavy chain, which in adult rat ventricle are indicators of hypertrophy, also increased. Ventricular expression of ET-1 mRNA was elevated in the norepinephrine group at 1, 2, and 3 days. By 5 days, this had fallen to control levels. In lung, kidney, and skeletal muscle, norepinephrine did not significantly increase expression of ET-1 mRNA. Bosentan attenuated norepinephrine-induced increases in ventricular weight, ratio of RNA to protein, and expression of skeletal alpha-actin mRNA and beta-myosin heavy chain mRNA at 5 days, but it did not attenuate increased ventricular expression of atrial natriuretic factor mRNA. CONCLUSIONS: These data suggest that endogenous ET-1 plays a direct role in mediating norepinephrine-induced ventricular hypertrophy in vivo.
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Samer Kaddoura
University of London
John D. Firth
Institute of Medical Ethics
Kenneth R. Boheler
Cross-Cutting Cardiology
Circulation
Royal Brompton Hospital
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Kaddoura et al. (Sat,) conducted a other in Norepinephrine-induced ventricular hypertrophy (n=70). Bosentan vs. Sham operation and/or norepinephrine alone was evaluated on Physical and molecular markers of ventricular hypertrophy (ventricular weight, RNA to protein ratio, mRNA expression). Bosentan attenuated norepinephrine-induced increases in ventricular weight, RNA to protein ratio, and specific hypertrophy marker mRNAs, suggesting ET-1 mediates ventricular hypertrophy in vivo.
synapsesocial.com/papers/6a091d694c1e2db30bd257f1 — DOI: https://doi.org/10.1161/01.cir.93.11.2068