The Morphology of Right Ventricular Papillary Muscle from Rats Exposed to 28 Days of Hypoxia

1990 ◽  
Vol 78 (s22) ◽  
pp. 5P-5P
Author(s):  
SV Baudouin ◽  
N Darius ◽  
NT Bateman
Keyword(s):  
Right Ventricular ◽  
Papillary Muscle

Contractile and Ca2+-handling properties of the right ventricular papillary muscle in the late-gestation sheep fetus

2006 ◽  
Vol 101 (3) ◽  
pp. 728-733 ◽  
Author(s):  
T. N. Spencer ◽  
K. J. Botting ◽  
J. L. Morrison ◽  
G. S. Posterino
Keyword(s):  
Right Ventricular ◽  
Papillary Muscle ◽  
Late Gestation ◽  
Postnatal Life ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Force Development ◽  
Uptake Rates ◽  
Significant Difference ◽  
The Right

The force-generating capacity of cardiomyocytes rapidly changes during gestation and early postnatal life coinciding with a transition in cardiomyocyte nucleation in both mice and rats. Changes in nucleation, in turn, appear to coincide with important changes in the excitation-contraction coupling architecture. However, it is not clear whether similar changes are observed in other mammals in which this transition occurs prenatally, such as sheep. Using small (70–300 μM diameter) chemically skinned cardiomyocyte bundles from the right ventricular papillary muscle of sheep fetuses at 126–132 and 137–140 days (d) gestational age (GA), we aimed to examine whether changes in cardiomyocyte nucleation during late gestation coincided with developmental changes in excitation-contraction coupling parameters (e.g., Ca2+ uptake, Ca2+ release, and force development). All experiments were conducted at room temperature (23 ± 1°C). We found that the proportion of mononucleate cardiomyocytes decreased significantly with GA (126–132d, 45.7 ± 4.7%, n = 7; 137–140d, 32.8 ± 1.6%, n = 6; P < 0.05). When we then examined force development between the two groups, there was no significant difference in either the maximal Ca2+-activated force (6.73 ± 1.54 mN/mm2, n = 14 vs. 6.55 ± 1.25 mN/mm2, n = 7, respectively) or the Ca2+ sensitivity of the contractile apparatus (pCa at 50% maximum Ca2+-activated force: 126–132d, 6.17 ± 0.06, n = 14; 137–140d, 6.24 ± 0.08, n = 7). However, sarcoplasmic reticulum (SR) Ca2+ uptake rates (but not Ca2+ release) increased with GA ( P < 0.05). These data reveal that during late gestation in sheep when there is a major transition in cardiomyocyte nucleation, SR Ca2+ uptake rates increase, which would influence total SR Ca2+ content and force production.

Chronic intermittent hypobaric hypoxia decreases β-adrenoceptor activity in right ventricular papillary muscle

2010 ◽  
Vol 298 (4) ◽  
pp. H1267-H1272 ◽  
Author(s):  
Yue Guan ◽  
Lu Gao ◽  
Hui-Jie Ma ◽  
Qian Li ◽  
Hao Zhang ◽  
...  
Keyword(s):  
Action Potential ◽  
Right Ventricular ◽  
Papillary Muscle ◽  
Action Potential Duration ◽  
Adrenergic Receptor ◽  
Hypobaric Hypoxia ◽  
Radioligand Binding ◽  
Ischemia Reperfusion ◽  
Intermittent Hypobaric Hypoxia ◽  
Membrane Bound

Chronic intermittent hypobaric hypoxia (CIHH) has an effective cardiac protection against ischemia-reperfusion injury. However, the underlying mechanisms are not fully known. It has been shown that blockade of β-adrenergic receptor exerts anti-arrhythmic action and improves cardiac remodeling in ischemic myocardium. Thus we determined the influence of CIHH on β-adrenergic receptor activity in right ventricular papillary muscle of rats. We found that the action potential duration in right ventricular papillary muscle was significantly longer in CIHH rats than in control rats. Activation of β-adrenergic receptor with dl-isoproterenol dose-dependently increased action potential duration and the contractility in right ventricular papillary muscle. In CIHH rats, the prolonged effect of dl-isoproterenol on action potential duration and the positive inotropic effect were significantly decreased compared with that in control rats. Furthermore, radioligand-binding experiments revealed that the density and affinity of β-adrenergic receptor in right ventricular myocardium was significantly lower in CIHH rats. In addition, Western blot analysis revealed that the membrane-bound G protein Gsα expression level in cardiac myocardium was significantly lower in CIHH rats than that in control rats. Collectively, these data suggest that CIHH suppresses β-adrenergic receptor action in right ventricular papillary muscle through decreasing receptor density and affinity, as well as membrane-bound Gsα. This mechanism may be involved in the cardiac protective effect of CIHH.

scholarly journals Right ventricular papillary muscle approximation for functional tricuspid regurgitation associated with severe leaflet tethering†

2017 ◽  
Vol 26 (4) ◽  
pp. 700-702 ◽  
Author(s):  
Goro Matsumiya ◽  
Hiroki Kohno ◽  
Kaoru Matsuura ◽  
Tomoki Sakata ◽  
Yusaku Tamura ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Papillary Muscle ◽  
Tricuspid Regurgitation ◽  
Functional Tricuspid Regurgitation

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.

scholarly journals Hybrid Logistic Characterization of Isometric Twitch Force-Time Curve of Intact Blood-Perfused Canine Right Ventricular Papillary Muscle.

1997 ◽  
Vol 47 (3) ◽  
pp. 283-289 ◽  
Author(s):  
Taisuke SAKAMOTO ◽  
Miyako TAKAKI ◽  
Yoshiki HATA ◽  
Hiromi MATSUBARA ◽  
Junichi ARAKI ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Papillary Muscle ◽  
Time Curve ◽  
Twitch Force ◽  
Isometric Twitch ◽  
Force Time

scholarly journals Hybrid Logistic Characterization of Isometric Twitch Force Curve of Isolated Ferret Right Ventricular Papillary Muscle.

1999 ◽  
Vol 49 (2) ◽  
pp. 145-158 ◽  
Author(s):  
Ju MIZUNO ◽  
Takeshi MIKANE ◽  
Junichi ARAKI ◽  
Mineko HATASHIMA ◽  
Toshiyuki MORITAN ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Papillary Muscle ◽  
Force Curve ◽  
Twitch Force ◽  
Isometric Twitch
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