Simultaneous cardiac mechanics and phosphorus‐31 NMR spectroscopy during myocardial ischemia and reperfusion in the intact dog

Miller, D. Douglas; Salinas, F.; Walsh, Richard A.

doi:10.1002/mrm.1910170109

Cited by 7 publications

(7 citation statements)

References 27 publications

(25 reference statements)

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“…However, it has been shown that results from experiments performed in closed-chest dogs are in accordance with results from experiments performed in open-chest dogs (157,158), thereby paving the way for longitudinal studies. After the onset of 5-min occlusion and during 30 min of reperfusion therapy, no change in PCr/ATP ratio was found in dogs (121). In swine, it has been shown that the PCr/ATP ratio is reduced at 4 weeks post-myocardial infarction (120).…”

Section: P-mrs: Results From Animal Studiesmentioning

confidence: 99%

MRS: a noninvasive window into cardiac metabolism

et al. 2015

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A well-functioning heart requires a constant supply of a balanced mixture of nutrients to be used for the production of adequate amounts of adenosine triphosphate, which is the main energy source for most cellular functions. Defects in cardiac energy metabolism are linked to several myocardial disorders. MRS can be used to study in vivo changes in cardiac metabolism noninvasively. MR techniques allow repeated measurements, so that disease progression and the response to treatment or to a lifestyle intervention can be monitored. It has also been shown that MRS can predict clinical heart failure and death. This article focuses on in vivo MRS to assess cardiac metabolism in humans and experimental animals, as experimental animals are often used to investigate the mechanisms underlying the development of metabolic diseases. Various MR techniques, such as cardiac (31) P-MRS, (1) H-MRS, hyperpolarized (13) C-MRS and Dixon MRI, are described. A short overview of current and emerging applications is given. Cardiac MRS is a promising technique for the investigation of the relationship between cardiac metabolism and cardiac disease. However, further optimization of scan time and signal-to-noise ratio is required before broad clinical application. In this respect, the ongoing development of advanced shimming algorithms, radiofrequency pulses, pulse sequences, (multichannel) detection coils, the use of hyperpolarized nuclei and scanning at higher magnetic field strengths offer future perspective for clinical applications of MRS.

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Section: P-mrs: Results From Animal Studiesmentioning

confidence: 99%

MRS: a noninvasive window into cardiac metabolism

et al. 2015

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“…These investigators18, 19) demonstrated that the phosphocreatine to inorganic phosphate ratio (PCr/Pi) was sensitive to reductions in myocardial blood flow and closely correlated with changes in contractile function. On the other hand, although significant correlations between changes in energy metabolism and myocardial contractility during ischemia were found in these previous studies,15,18-20) the duration of ischemia was insufficient to produce stunning [18][19][20] or the monitoring during reperfusion was intermittent and of short duration.5)…”

mentioning

confidence: 89%

Simultaneous Evaluations of Contractility and Energy Metabolism of Stunned Myocardium Using 31P Magnetic Resonance Spectroscopy.

Geshi

Sordahl²,

Ito

et al. 1998

Jpn Heart J

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A canine model of postischemic myocardial dysfunction (15 min ischemia, 60 min reperfusion) was used to evaluate the relationship between energy metabolism and myocardial contractile function by on-line measurements of ECG, left ventricular pressure, coronary blood flow and regional segment shortening (%SS) with the continuous acquisition of 31PMR spectra. Two groups emerged from these studies; the first (n=7) in which regional myocardial %SS remained significantly depressed after 60 min of reperfusion (stunned) and the second (n=5) in which regional %SS returned to control levels after 60 min of reperfusion (non-stunned). Both groups exhibited rapid, similar decreases in %SS and parallel rapid decreases in the phosphocreatine to inorganic phosphate (PCr/Pi) ratio with the onset of ischemia. The PCr/ATP ratio exceeded control levels in the stunned group immediately upon reperfusion and remained significantly above control after 60 min of reperfusion. Measurements of tissue myocardial creatine kinase (CK) revealed a significant decrease in total tissue CK activity in stunned myocardium compared to control. A significant inverse relationship (r=-0.904, p<0.003) was found between myocardial tissue CK specific activity and the PCr/ATP ratios. We postulate that the elevated PCr/ATP ratio caused by the impairment of energy transfer to the contractile apparatus constitutes a contractile dysfunction in the postischemic heart.

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“…Nonetheless, while it seems obvious that perturbation of cardiac energetics contributes to the failure of an oxygen-starved heart, the exact mechanisms underlying the decline in cardiac contractile function during oxygen deprivation remain equivocal despite decades of research (1,81). Some studies propose that depletion of high-energy phosphates [ATP and phosphocreatine (PCr)] and/or accumulation of metabolic by-products such as H ϩ , ADP, and inorganic phosphate (P i ) causes cardiac function to deteriorate (2,15,16,22,26,27,50,63,81). Others argue against such mechanisms (3,14,44,50,62).…”

mentioning

confidence: 99%

“…Some studies propose that depletion of high-energy phosphates [ATP and phosphocreatine (PCr)] and/or accumulation of metabolic by-products such as H ϩ , ADP, and inorganic phosphate (P i ) causes cardiac function to deteriorate (2,15,16,22,26,27,50,63,81). Others argue against such mechanisms (3,14,44,50,62). Moreover, the potential roles of decreased turnover of high-energy phosphate compounds (7), reduced phosphorylation potential (i.e., [ATP]/[ADP] ϫ [P i ]) (14), and the decrease in free energy released from ATP hydrolysis (dG/d) (41,42,49) are equally ambiguous.…”

mentioning

confidence: 99%

Correlation of cardiac performance with cellular energetic components in the oxygen-deprived turtle heart

Stecyk¹,

Bock²,

Overgaard³

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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The relationship between cardiac energy metabolism and the depression of myocardial performance during oxygen deprivation has remained enigmatic. Here, we combine in vivo (31)P-NMR spectroscopy and MRI to provide the first temporal profile of in vivo cardiac energetics and cardiac performance of an anoxia-tolerant vertebrate, the freshwater turtle (Trachemys scripta) during long-term anoxia exposure (approximately 3 h at 21 degrees C and 11 days at 5 degrees C). During anoxia, phosphocreatine (PCr), unbound levels of inorganic phosphate (effective P(i)(2-)), intracellular pH (pH(i)), and free energy of ATP hydrolysis (dG/dxi) exhibited asymptotic patterns of change, indicating that turtle myocardial high-energy phosphate metabolism and energetic state are reset to new, reduced steady states during long-term anoxia exposure. At 21 degrees C, anoxia caused a reduction in pH(i) from 7.40 to 7.01, a 69% decrease in PCr and a doubling of effective P(i)(2-). ATP content remained unchanged, but the free energy of ATP hydrolysis (dG/dxi) decreased from -59.6 to -52.5 kJ/mol. Even so, none of these cellular changes correlated with the anoxic depression of cardiac performance, suggesting that autonomic cardiac regulation may override putative cellular feedback mechanisms. In contrast, during anoxia at 5 degrees C, when autonomic cardiac control is severely blunted, the decrease of pH(i) from 7.66 to 7.12, 1.9-fold increase of effective P(i)(2-), and 6.4 kJ/mol decrease of dG/dxi from -53.8 to -47.4 kJ/mol were significantly correlated to the anoxic depression of cardiac performance. Our results provide the first evidence for a close, long-term coordination of functional cardiac changes with cellular energy status in a vertebrate, with a potential for autonomic control to override these immediate relationships.

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Simultaneous cardiac mechanics and phosphorus‐31 NMR spectroscopy during myocardial ischemia and reperfusion in the intact dog

Cited by 7 publications

References 27 publications

MRS: a noninvasive window into cardiac metabolism

MRS: a noninvasive window into cardiac metabolism

Simultaneous Evaluations of Contractility and Energy Metabolism of Stunned Myocardium Using 31P Magnetic Resonance Spectroscopy.

Correlation of cardiac performance with cellular energetic components in the oxygen-deprived turtle heart

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