Right ventricular performance after monocrotaline-induced pulmonary hypertension

Area of Science:

• Cardiovascular Physiology
• Pulmonary Hypertension Research
• Cardiac Hypertrophy Studies

Background:

• Chronic pulmonary hypertension triggers compensatory right ventricular (RV) hypertrophy.
• RV performance in hypertrophy varies based on overload type, severity, species, age, and sex.
• Understanding RV adaptation to pressure overload is crucial for cardiovascular disease research.

Purpose of the Study:

• To investigate the functional consequences of chronic RV pressure overload and hypertrophy in male Sprague-Dawley rats.
• To utilize novel methods for assessing hypertrophied RV performance in vivo and in vitro.
• To determine if RV hypertrophy induced by monocrotaline (MCT) leads to impaired cardiac function or enhanced performance.

Main Methods:

• Induction of chronic pulmonary hypertension and RV hypertrophy using monocrotaline (MCT) in male Sprague-Dawley rats.
• Measurement of RV-to-(left ventricle + septum) ratio and isolated right ventricular myocyte dimensions.
• Adaptation of an isolated, working heart preparation to assess in vitro RV function under varying preloads.

Main Results:

• MCT treatment significantly increased the RV-to-(left ventricle + septum) ratio by 94% after 5 weeks.
• Isolated right ventricular myocytes showed increased volume, primarily due to enhanced cell cross-sectional area.
• In vitro studies revealed elevated ventricular performance in hypertrophied RVs, with enhanced pressure development and relaxation rates (dP/dtmax).

Conclusions:

• Monocrotaline-induced RV hypertrophy in rats results in enhanced, not diminished, ventricular performance.
• The hypertrophied right ventricle demonstrates improved pressure generation and relaxation capabilities.
• This study provides evidence against RV failure in chronic pressure overload models using MCT, suggesting adaptive mechanisms.