Intracellular pH and inorganic phosphate content of heart in vivo: a 31P-NMR study

Katz, L. A.; Swain, Julie A.; Portman, Michael A.; Balaban, R. S.

doi:10.1152/ajpheart.1988.255.1.h189

Cited by 52 publications

(55 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Errors in impalement or severe disruption of cell membranes may yield "tissue" pH readings which are actually from a hybrid of interstitial and intracellular environment. This results in higher intracellular pH readings than found during nuclear magnetic resonance studies (5,19,20), as well as the assumption that myocardial intracellular pH is closely related to tissue (19,20). Results of in vivo pH electrode studies generally show that intracellular pH changes in magnitude similar to extracellular pH.…”

Section: Discussionmentioning

confidence: 88%

“…3"Phosphorous nuclear magnetic resonance spectroscopy (31P NMR)' is now the primary tool for studying these relations in vivo (1)(2)(3)(4)(5). NMR yields dynamic measurements of intracellular phosphate and avoids overestimation errors associated with freeze clamp and acid extraction techniques (6).…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, intracellular pH can be calculated concomitantly from the chemical shift of the monophosphate resonance peak (7,8). NMR analysis of myocardial intracellular monophosphate levels and pH has been complicated by the contamination of the Pi resonance peaks by phosphomonoesters, particularly 2,3-diphosphoglycerate (2,3-DPG), present in blood perfusing the myocardium or within the ventricular chamber (5). This problem has been circumvented in mature myocardium by studying sheep (1,9), a species in which blood 2,3-DPG levels drop dramatically after the first week of life (10).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Developmental adaptations in cytosolic phosphate content and pH regulation in the sheep heart in vivo.

Portman

Xue

1990

J. Clin. Invest.

View full text Add to dashboard Cite

This study examines adaptations in myocardial cytosolic phosphate content and buffering capacity that occur in vivo as a function of development. Phosphate metabolites were monitored in an open chest sheep preparation using a 31p magnetic resonance surface coil over the left ventricle. Newborn lambs (aged 4-9 d, n = 5) underwent exchange transfusion with adult blood to reduce blood-borne 2,3-diphosphoglycerate contamination of the heart monophosphate and phosphomonoester resonances, thus allowing determination of these phosphate concentrations. The blood-exchanged newborns and mature controls (aged 30-60 d, n = 5) were infused with 0.4 N hydrochloric acid to decrease pH from > 7.35 to < 7.00. Simultaneously, intracellular and extracellular pH were determined from the chemical shifts of the respective phosphate peaks and compared to arterial blood pH. Findings were as follows: (a) diphosphoglycerate contribution to the cardiac spectrum was found to be negligible, (b) significant decreases in cytosolic phosphate (P < 0.03) and phosphomonoester (P < 0.01) content occurred with maturation, and (c) large decreases in extracellular pH (> 0.5 U) in both groups were similarly associated with only small changes in intracellular pH (< 0.1 U).

show abstract

Section: Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Developmental adaptations in cytosolic phosphate content and pH regulation in the sheep heart in vivo.

Portman

Xue

1990

J. Clin. Invest.

View full text Add to dashboard Cite

show abstract

“…Therefore, it is likely that subepicardial areas of the left ventricle contributed more to the signal than other regions (18). Lack of 2,3 diphosphoglycerate peaks in sheep heart phosphorous spectra does not indicate that signal is obtained primarily from epicardium.…”

Section: F102(%)mentioning

confidence: 93%

Relation of myocardial oxygen consumption and function to high energy phosphate utilization during graded hypoxia and reoxygenation in sheep in vivo.

Portman¹,

Standaert²,

Ning³

1995

J. Clin. Invest.

View full text Add to dashboard Cite

IntroductionThis study investigates the relation between myocardial oxygen consumption (MV 02), function, and high energy phos- Severe hypoxia ultimately leads to contractile failure, which is attributed to an imbalance between myocardial oxygen supply and demand (1)(2)(3)(4). Sudden extreme oxygen deprivation causes rapid depletion of energy stores in the form of the high energy phosphates, phosphocreatine, and ATP, as well as accumulation of ATP hydrolysis products. In isolated myocytes (5) and buffer-perfused hearts (5, 6) anoxia or hypoxia results in a reduced oxidative phosphorylation rate. Myocardial respiration wanes despite increasing ADP and intracellular phosphate (Pi),' which both stimulate mitochondrial ATP production under aerobic conditions. The intact animal generally maintains or increases myocardial oxygen consumption during early or moderate hypoxia (7-9). Small decreases in myocardial phosphocreatine content with no depletion of the cytosolic ATP pool have been documented during moderate hypoxic conditions (10, 11). However, myocardial oxygen consumption rates have not been directly measured during periods of rapid high energy phosphate depletion and repletion in the intact animal. The purpose of this study was to examine the relation between myocardial oxygen consumption, function, and high energy phosphates during severe hypoxia and reoxygenation in vivo. Additionally, rephosphorylation parameters were measured to determine if evidence of respiratory uncoupling or mitochondrial damage occurs during reoxygenation in vivo. Graded hypoxia was performed in an effort to gradually reduce arterial oxygen tension to attain the P02 at which high energy phosphate stores rapidly decreased. Highly time-resolved 31P nuclear magnetic resonance (NMR) spectroscopy enabled monitoring of myocardial phosphates throughout hypoxia and recovery with simultaneous measurement of oxygen consumption. Consequently, these measurements enhanced analysis of mitochondrial function in vivo during reoxygenation. MethodsAnimal preparation. Animals used in this study were handled in accordance with institutional and National Institutes of Health animal care and use guideline. Sheep between 30 and 70 d old (mean 47 d±6.8) were sedated with an intramuscular injection of 10 mg/kg ketamine, and 0.2-0.4 mg/kg xylazine, intubated, and then ventilated (C-900 pediatric ventilator; Siemens Corp., Schaumberg, IL) with room air and oxygen, followed by an intravenous dose of alpha-chloralose (40 mg/ kg). Femoral arterial cannulation was performed for monitoring systemic blood pressure and sampling blood. Arterial pH was maintained between 7.35 and 7.45 by adjustment of ventilatory tidal volume and 1. Abbreviations used in this paper: FIo2, fractional inspiratory oxygen

show abstract

“…There was, in other words, a response to changes in arterial pH, such as the hypoxic state, which demonstrated an effective myocardial intracelluar protonbuffering mechanism. In experimental study (29) in which a linear function was applied to the results, the relationship between arterial pH and pHi was as follows: pHi=0.23 arterial pH +5.43…”

mentioning

confidence: 99%

(31)P MR Spectroscopic Measurement of Intracellular pH in Normal Human Hearts

Kwon

Lee

Jang

et al. 2002

J Korean Radiol Soc

View full text Add to dashboard Cite

Purpose:To assess the usefulness of intracellular pH (pHi), calculated by determining the shift of a high-energy metabolite such as inorganic phosphate (Pi) or -ATP after performing MRS with ECG-gated two-dimensional 31 P CSI (chemical shift imaging), as a parameter for the overall state of the intracellular milieu. Materials and Methods: Proton decoupled 31 P CSI was performed on a 1.5-T scanner using a 1 H-31 P dual-tuned surface coil. Cardiac MRS data were obtained from eight normal volunteers aged 24 32 years with no history of heart disease. From the spectra obtained from several regions of the heart, peak position and peak area were estimated. The metabolic ratios of -, -, -ATP, PCr, Pi, phosphodiester and diphosphoglycerate were calculated, and pHi was estimated from the chemical shift of Pi and -ATP resonance. We then compared the data for the anterior myocardium with those previously published. Results: The major phosphorous metabolites identified in these human hearts were as follows: PCr, at 0.1 to +0.1 ppm; three phosphate peaks from ATP, with a chemical shift centered at about 2.7 ppm ( -ATP), 7.8 ppm ( -ATP), and 16.3 ppm ( -ATP); and phosphodiester (PDE) at 2 3 ppm, inorganic phosphate (Pi) at 4.5 5.4 ppm, and diphosphoglycerate (DPG) at 5.4 6.3 ppm. The PCr/ -ATP ratio was 2.20 0.17 and the PDE/ -ATP ratio, 1.04 0.09. pHi readings were 7.31 0.23 (calculated by the shift of Pi) and 6.81 0.20 (calculated by the shift of -ATP). Pi/PCR was 0.539, a ratio higher than that mentioned in previously published reports. Conclusion: The measurement of intracelluar metabolism was affected by various kinds of factors. We believe, however, that pHi readings indicate the overall state of the cardiac intracelluar milieu. An unexpected pHi readings, seen at MRS, may reflect errors in the MR procedure itself and, or in the alanytical method.

show abstract

Intracellular pH and inorganic phosphate content of heart in vivo: a 31P-NMR study

Cited by 52 publications

References 0 publications

Developmental adaptations in cytosolic phosphate content and pH regulation in the sheep heart in vivo.

Developmental adaptations in cytosolic phosphate content and pH regulation in the sheep heart in vivo.

Relation of myocardial oxygen consumption and function to high energy phosphate utilization during graded hypoxia and reoxygenation in sheep in vivo.

(31)P MR Spectroscopic Measurement of Intracellular pH in Normal Human Hearts

Contact Info

Product

Resources

About