Regulation of Respiration and Pyruvate Dehydrogenase in Isolated Cardiac Myocytes and Hepatocytes

1988 ◽  
pp. 235-244 ◽  
Author(s):  
Richard G. Hansford ◽  
Rafael Moreno-Sánchez ◽  
James Staddon
Keyword(s):  
Cardiac Myocytes ◽  
Pyruvate Dehydrogenase ◽  
Regulation Of Respiration ◽  
Isolated Cardiac Myocytes

scholarly journals Relation between cytosolic free Ca2+ concentration and the control of pyruvate dehydrogenase in isolated cardiac myocytes

1987 ◽  
Vol 241 (1) ◽  
pp. 145-151 ◽  
Author(s):  
R G Hansford
Keyword(s):  
Cardiac Myocytes ◽  
Pyruvate Dehydrogenase ◽  
Energy Supply ◽  
Supply And Demand ◽  
Active Form ◽  
Chelating Agent ◽  
Work Load ◽  
Ruthenium Red ◽  
Isolated Cardiac Myocytes ◽  
Physiological Values

The proportion of pyruvate dehydrogenase existing in the active form (PDHA) in suspensions of unstimulated cardiac myocytes oxidizing glucose is approx. 30%. Depolarization of the cells with concentrations of K+ above physiological values leads to an increase in the content of PDHA. Overloading of the cells with Na+ by treatment with veratridine and ouabain gives the same result. Each of these interventions is shown in experiments with Quin 2-loaded myocytes to lead to an increase in cytosolic free Ca2+ concentration ([Ca2+]c). Treatment of the cells with Ruthenium Red, an inhibitor of Ca2+ transport into mitochondria, largely prevents an increase in PDHA in response to addition of KCl or of veratridine plus ouabain. Ruthenium Red does not attenuate the increase in [Ca2+]c that occurs under these conditions. By contrast, treatment of the cells with ryanodine, an inhibitor of sarcoplasmic-reticulum Ca2+ transport and therefore of contraction, does not diminish the response of PDHA content to agents which raise [Ca2+]c; nor does loading of the cells with the Ca2+-chelating agent Quin 2, which also prevents contraction, at appropriate concentrations. It is concluded that an increase in [Ca2+]c causes an increase in PDHA content of cardiac myocytes independently of an increase in mechanical work. In the normal physiological situation the activation of dehydrogenases by Ca2+ is thought to help to maintain the balance of energy supply and demand during periods of increased work-load, which are associated with an increased myoplasmic [Ca2+]c.

l-Arginine ameliorates effects of ischemia and reperfusion in isolated cardiac myocytes

2003 ◽  
Vol 476 (1-2) ◽  
pp. 45-54 ◽  
Author(s):  
Adrian Au ◽  
William E. Louch ◽  
Gregory R. Ferrier ◽  
Susan E. Howlett
Keyword(s):  
Cardiac Myocytes ◽  
Ischemia And Reperfusion ◽  
Isolated Cardiac Myocytes

Differential effects of phospholamban and Ca2+/calmodulin-dependent kinase II on [Ca2+]i transients in cardiac myocytes at physiological stimulation frequencies

2008 ◽  
Vol 294 (5) ◽  
pp. H2352-H2362 ◽  
Author(s):  
Andreas A. Werdich ◽  
Eduardo A. Lima ◽  
Igor Dzhura ◽  
Madhu V. Singh ◽  
Jingdong Li ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Sarcoplasmic Reticulum ◽  
Cardiac Myocytes ◽  
Wild Type ◽  
Dependent Protein Kinase ◽  
Frequency Dependent ◽  
Physiological Range ◽  
Dependent Protein ◽  
Isolated Cardiac Myocytes

In cardiac myocytes, the activity of the Ca2+/calmodulin-dependent protein kinase II (CaMKII) is hypothesized to regulate Ca2+ release from and Ca2+ uptake into the sarcoplasmic reticulum via the phosphorylation of the ryanodine receptor 2 and phospholamban (PLN), respectively. We tested the role of CaMKII and PLN on the frequency adaptation of cytosolic Ca2+ concentration ([Ca2+]i) transients in nearly 500 isolated cardiac myocytes from transgenic mice chronically expressing a specific CaMKII inhibitor, interbred into wild-type or PLN null backgrounds under physiologically relevant pacing conditions (frequencies from 0.2 to 10 Hz and at 37°C). When compared with that of mice lacking PLN only, the combined chronic CaMKII inhibition and PLN ablation decreased the maximum Ca2+ release rate by more than 50% at 10 Hz. Although PLN ablation increased the rate of Ca2+ uptake at all frequencies, its combination with CaMKII inhibition did not prevent a frequency-dependent reduction of the amplitude and the duration of the [Ca2+]i transient. High stimulation frequencies in the physiological range diminished the effects of PLN ablation on the decay time constant and on the maximum decay rate of the [Ca2+]i transient, indicating that the PLN-mediated feedback on [Ca2+]i removal is limited by high stimulation frequencies. Taken together, our results suggest that in isolated mouse ventricular cardiac myocytes, the combined chronic CaMKII inhibition and PLN ablation slowed Ca2+ release at physiological frequencies: the frequency-dependent decay of the amplitude and shortening of the [Ca2+]i transient occurs independent of chronic CaMKII inhibition and PLN ablation, and the PLN-mediated regulation of Ca2+ uptake is diminished at higher stimulation frequencies within the physiological range.

Inhibition of pyruvate dehydrogenase kinase by pyruvate in cultured cardiac myocytes

1997 ◽  
Vol 25 (1) ◽  
pp. 101S-101S ◽  
Author(s):  
DAVID A. PRIESTMAN ◽  
KAREN A. ORFALI ◽  
MARY C. SUGDEN
Keyword(s):  
Cardiac Myocytes ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Kinase

scholarly journals The kinetics of transport of lactate and pyruvate into isolated cardiac myocytes from guinea pig. Kinetic evidence for the presence of a carrier distinct from that in erythrocytes and hepatocytes

1989 ◽  
Vol 264 (2) ◽  
pp. 409-418 ◽  
Author(s):  
R C Poole ◽  
A P Halestrap ◽  
S J Price ◽  
A J Levi
Keyword(s):  
Guinea Pig ◽  
Cardiac Myocytes ◽  
Ventricular Myocytes ◽  
Silicone Oil ◽  
Free Acid ◽  
Competitive Inhibitor ◽  
Isolated Cardiac Myocytes ◽  
Lactate And Pyruvate ◽  
Time Courses ◽  
Kinetics Of

1. Time courses for the uptake of L-lactate, D-lactate and pyruvate into isolated cardiac ventricular myocytes from guinea pig were determined at 11 degrees C or 0 degrees C (for pyruvate) in a citrate-based buffer by using a silicone-oil-filtration technique. These conditions enabled initial rates of transport to be measured without interference from metabolism of the substrates. 2. At a concentration of 0.5 mM, transport of all these substrates was inhibited by approx. 90% by 5 mM-alpha-cyano-4-hydroxycinnamate; at 10 mM-L-lactate a considerable portion of transport could not be inhibited. 3. Initial rates of L-lactate and pyruvate uptake in the presence of 5 mM-alpha-cyano-4-hydroxycinnamate were linearly related to the concentration of the monocarboxylate and probably represented diffusion of the free acid. The inhibitor-sensitive component of uptake obeyed Michaelis-Menten kinetics, with Km values for L-lactate and pyruvate of 2.3 and 0.066 mM respectively. 4. Pyruvate and D-lactate inhibited the transport of L-lactate, with Ki values (competitive) of 0.077 and 6.6 mM respectively; the Ki for pyruvate was very similar to its Km for transport. The Ki for alpha-cyano-4-hydroxycinnamate as a non-competitive inhibitor was 0.042 mM. 5. These results indicate that L-lactate, D-lactate and pyruvate share a common carrier in guinea-pig cardiac myocytes; the low stereoselectivity for L-lactate over D-lactate and the high affinity for pyruvate distinguish it from the carrier in erythrocytes and hepatocytes. The metabolic roles for this novel carrier in heart are discussed.

Abstract 1076: Conditional Fkbp12.6 Overexpression In Mouse Cardiac Myocytes Protects From Triggered Ventricular Arrhythmia Through Specific Alteration In Ec Coupling

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Barnabas Gellen ◽  
Ana-Maria Gomez ◽  
Khai Le Quang ◽  
Francois Briec ◽  
Laurent Vinet ◽  
...  
Keyword(s):  
Cardiac Myocytes ◽  
Antiarrhythmic Effect ◽  
Adrenergic Stimulation ◽  
Patch Clamp Technique ◽  
Ec Coupling ◽  
Before And After ◽  
Isolated Cardiac Myocytes ◽  
Pre Treatment ◽  
Specific Alteration ◽  
Ventricular Tachycardias

In cardiac myocytes, Ca2+ release from the sarcoplasmic reticulum (SR) into the cytoplasm via the ryanodine receptor (RyR2) activates cell contraction. During diastole, RyR2 are closed and prevent Ca2+ efflux from the SR. One of the major regulators of RyR2 function is FKBP12.6. Binding of FKBP12.6 stabilizes RyR2 in the closed formation in diastole and contributes to synchronized RyR2 opening in systole. Beta-adrenergic stimulation dissociates FKBP12.6 from RyR2, leading to diastolic Ca2+ leak that can trigger ventricular tachycardias (VT). We tested the hypothesis whether FKBP12.6 overexpression in the myocardium can reduce the susceptibility to VT in stress conditions. We developed a mouse model with conditional cardiac specific overexpression of FKBP12.6 using the Tet-Off system. Transgenic (TG) mice and controls (CT) were examined by echocardiography, PV-catheterization, ECG, and underwent intracardiac stimulation to trigger VT before and after pre-treatment with isoproterenol. In isolated cardiac myocytes, SR Ca2+ load, Ca2+ sparks and Ca2+ transient were measured using confocal microscopy, and L-type Ca2+ current was determined by the patch-clamp technique. Echocardiography, PV-catheterization and ECG recording did not reveal differences between Tg (n=11) and CT (n=13) mice. Burst pacing (figure 1) could induce TV in 4 of 24 controls and in 0 of 14 TG mice (n.s.). Following pre-treatment with isoproterenol, TV could be induced in 10 of 23 controls, but only in 1 of 14 TG animals (figure 2, p<0.05). In isolated myocytes, decreased Ca2+ spark frequency, increased Ca2+ spark size, unchanged SR Ca2+ load and decreased Ca2+ transient were observed in TG cells (n=19) as compared to controls (n=48, p<0.05). L-type Ca2+ channel current was found to be decreased in Tg myocytes (n=29 vs n=32, p<0.01). We conclude that myocardial FKBP12.6 overexpression has a protective effect against VT induced by rapid pacing after pretreatment with catecholamines. This antiarrhythmic effect is probably, at least in part, linked to decreased diastolic SR Ca2+ leak. Our results support the hypothesis that increased FKBP12.6 binding to RyR2 might represent a potential therapeutical target in the prevention and treatment of ventricular arrhythmias.

Sign in / Sign up

Export Citation Format

Share Document