scholarly journals Work and oxygen consumption of isolated right ventricular papillary muscle in experimental pulmonary hypertension

2021 ◽  
Author(s):  
Willem J. van der Laarse ◽  
Sylvia J.P. Bogaards ◽  
Ingrid Schalij ◽  
Anton Vonk Noordegraaf ◽  
Frédérick M. Vaz ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Oxygen Consumption ◽  
Cytochrome C ◽  
Right Ventricular ◽  
Mitochondrial Dysfunction ◽  
Papillary Muscle ◽  
Mechanical Efficiency ◽  
Cross Bridge ◽  
Cytosolic Cytochrome ◽  
Activation Heat

Right-sided myocardial mechanical efficiency (work output/metabolic energy input) in pulmonary hypertension can be severely reduced. We determined the contribution of intrinsic myocardial determinants of efficiency using papillary muscle preparations from monocrotaline-induced pulmonary hypertensive (MCT-PH) rats. The hypothesis was tested that efficiency is reduced by mitochondrial dysfunction in addition to increased activation heat reported previously. Right ventricular (RV) muscle preparations were subjected to 5 Hz sinusoidal length changes at 37°C. Work and suprabasal oxygen consumption (VO2) were measured before and after cross-bridge inhibition by blebbistatin. Cytosolic cytochrome c concentration, myocyte cross-sectional area, proton permeability of the inner mitochondrial membrane (PP IMM), and monoamine oxidase (MAO)-A and glucose 6-phosphate dehydrogenase (G-6-PDH) activities and phosphatidylglycerol (PG) and cardiolipin (CL) contents were determined. Mechanical efficiency ranged from 23 to 11% in control (n = 6) and from 22 to 1% in MCT-PH (n = 15) and correlated with work (r2 = 0.68, P < 0.0001) but not with VO2 (r2 = 0.004, P = 0.7919). VO2 for cross-bridge cycling was proportional to work (r2 = 0.56, P = 0.0005). Blebbistatin-resistant VO2 (r2 = 0.32, P = 0.0167) and IMM PP (r2 = 0.36, P = 0.0110) correlated inversely with efficiency. Together, these variables explained the variance of efficiency (coefficient of multiple determination R2 = 0.79, P = 0.0001). Cytosolic cytochrome c correlated inversely with work (r2 = 0.28, P = 0.0391), but not with efficiency (r2 = 0.20, P = 0.0867). G-6-PDH, MAO-A and PG/CL increased in the RV wall of MCT-PH but did not correlate with efficiency. Reduced myocardial efficiency in MCT-PH is due to activation processes and mitochondrial dysfunction. The variance of work and the ratio of activation heat reported previously and blebbistatin-resistant VO2 are discussed.

Effects of epinephrines on metabolism and contraction of cat papillary muscle

1964 ◽  
Vol 206 (3) ◽  
pp. 525-530 ◽  
Author(s):  
Kwang Soo Lee ◽  
Dai Hyun Yu
Keyword(s):  
Oxygen Consumption ◽  
Papillary Muscle ◽  
Heart Muscle ◽  
Mechanical Efficiency ◽  
Metabolic Efficiency ◽  
Metabolic State ◽  
Cat Papillary Muscle ◽  
Sympathomimetic Amines ◽  
Tissue Contents

The change of metabolic state and contractility of heart induced by epinephrine and norepinephrine was studied in in vitro preparations of cat papillary muscle. The oxygen consumption, glycogen content, energy-rich phosphate content, and contractility of muscles were measured simultaneously whenever possible by techniques described previously. It was found that these amines did not change significantly the tissue contents of energy-rich phosphate compounds and glycogen in these conditions. The oxygen consumption and contractility of muscles were markedly influenced by the sympathomimetic amines. The change of metabolic efficiency as measured by the ratio, contractile tension : total Qo2, following the administration of these amines were dependent on the condition of heart muscles at the time of administration of these agents. Thus, when muscles were fresh, the metabolic efficiency was not significantly changed by the amines. However, when muscles were in the hypodynamic state, the amines were found to increase the metabolic efficiency of the heart muscle significantly. This suggests that the metabolic state of heart muscle should be taken into consideration whenever the influence of these sympathomimetic amines on the mechanical efficiency of heart is investigated.

Skeletal muscle mitochondrial dysfunction precedes right ventricular impairment in experimental pulmonary hypertension

2012 ◽  
Vol 373 (1-2) ◽  
pp. 161-170 ◽  
Author(s):  
Irina Enache ◽  
Anne-Laure Charles ◽  
Jamal Bouitbir ◽  
Fabrice Favret ◽  
Joffrey Zoll ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Pulmonary Hypertension ◽  
Right Ventricular ◽  
Mitochondrial Dysfunction

scholarly journals Adaptive right ventricular performance in response to acutely increased afterload in a lamb model of congenital heart disease: evidence for enhanced Anrep effect

2014 ◽  
Vol 306 (8) ◽  
pp. H1222-H1230 ◽  
Author(s):  
Rebecca C. Johnson ◽  
Sanjeev A. Datar ◽  
Peter E. Oishi ◽  
Stephen Bennett ◽  
Jun Maki ◽  
...  
Keyword(s):  
Congenital Heart Disease ◽  
Pulmonary Hypertension ◽  
Heart Disease ◽  
Cardiac Index ◽  
Pulmonary Artery ◽  
Right Ventricular ◽  
Congenital Heart ◽  
Mechanical Efficiency ◽  
Ventricular Performance ◽  
Therapeutic Implications

Patients with pulmonary hypertension associated with congenital heart disease survive longer with preserved right ventricular (RV) function compared with those with primary pulmonary hypertension. The purpose of this study was to test the hypothesis that superior RV performance can be demonstrated, at baseline and when challenged with increased RV afterload, in lambs with chronic left-to-right cardiac shunts compared with control lambs. A shunt was placed between the pulmonary artery and the aorta in fetal lambs (shunt). RV pressure-volume loops were obtained 4 wk after delivery in shunt and control lambs, before and after increased afterload was applied using pulmonary artery banding (PAB). Baseline stroke volume (8.7 ± 1.8 vs. 15.8 ± 2.7 ml, P = 0.04) and cardiac index (73.0 ± 4.0 vs. 159.2 ± 25.1 ml·min−1·kg−1, P = 0.02) were greater in shunts. After PAB, there was no difference in the change in cardiac index (relative to baseline) between groups; however, heart rate (HR) was greater in controls (168 ± 7.3 vs. 138 ± 6.6 beats/min, P = 0.01), and end-systolic elastance (Ees) was greater in shunts (2.63 vs. 1.31 × baseline, P = 0.02). Control lambs showed decreased mechanical efficiency (71% baseline) compared with shunts. With acute afterload challenge, both controls and shunts maintained cardiac output; however, this was via maladaptive responses in controls, while shunts maintained mechanical efficiency and increased contractility via a proposed enhanced Anrep effect—the second, slow inotropic response in the biphasic ventricular response to increased afterload, a novel finding in the RV. The mechanisms related to these physiological differences may have important therapeutic implications.

Sign in / Sign up

Export Citation Format

Share Document