Mechanism of preconditioning: Ionic alterations

Charles Jr Steenbergen, Michael E. Perlman, Robert E. London, Elizabeth Murphy

Research output: Contribution to journalArticle

Abstract

The mechanism by which preconditioning (brief intermittent periods of ischemia and reflow) improves recovery of function and reduces enzyme release after a subsequent 30-minute period of ischemia was investigated in perfused rat hearts. Specifically, it was hypothesized that ischemia after preconditioning would result in a decreased production of H+ and therefore a smaller rise in [Na+]i and [Ca2+]i via Na+-H+ and Na+-Ca2+ exchange. To test this hypothesis we measured pHi, [Na+]i, [Ca2+]i, and cell high-energy phosphates during ischemia and reflow, and we correlated this with recovery of contractile function and release of creatine kinase during reflow. 31P nuclear magnetic resonance (NMR) was used to measure pHi and cell phosphates. [Na+]i was measured by 23Na NMR using the shift reagent thulium 1,4,7,10-tetraazacyclododecane-N,N,′N″,N‴- tetramethylenephosphonate to distinguish intracellular from extracellular sodium. [Ca2+]i was measured by 19F NMR using hearts loaded with 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N′,N′-tetraacetic acid, termed 5F-BAPTA. Basal time-averaged levels of pHi, [Na+]i, and [Ca2+]i were 7.07±0.08, 9.4±0.8 mM, and 715±31 nM, respectively. After 30 minutes of ischemia, in preconditioned hearts, PHi was 6.5±0.06, [Na+]i was 20.9±4.4 mM, [Ca2+]i was 2.1±0.4 μM, and ATP was negligible. In untreated hearts, after 30 minutes of ischemia, pH, was 6.3±0.08, [Na+]i was 26.7±3.8 mM, [Ca2+]i was 3.2±0.6 μM, and ATP was undetectable. During reperfusion after 30 minutes of ischemia, preconditioned hearts had significantly better recovery of contractile function than untreated hearts (71±9% versus 36±8% initial left ventricular developed pressure), and after 60 minutes of ischemia, preconditioned hearts had significantly less release of the intracellular enzyme creatine kinase (102±12 versus 164±17 IU/g dry wt). We also found that unpreconditioned hearts arrested with 16 mM MgCl2 (to inhibit calcium entry via calcium channels and Na+-Ca2+ exchange) before 30 minutes of ischemia recover function on reflow to the same extent as preconditioned hearts with or without magnesium arrest. Thus, preconditioning has no additional benefit in addition to magnesium arrest. In addition, in hearts that received 16 mM MgCl2 just before the 30-minute period of ischemia, preconditioning had no effect on the rise in [Ca2+]i during the 30-minute period of ischemia. These data support the hypothesis that preconditioning attenuates the increase in [Ca2+]i, [Na+]i, and [H+]i during ischemia, most likely because of reduced stimulation of Na+-H+ and Na+-Ca2+ exchange. The data suggest that interventions that minimize ionic derangements during ischemia are associated with improved recovery of contractility and less enzyme release on reflow.

Original languageEnglish (US)
Pages (from-to)112-125
Number of pages14
JournalCirculation Research
Volume72
Issue number1
StatePublished - Jan 1993
Externally publishedYes

Fingerprint

Ischemia
Recovery of Function
Magnesium Chloride
Magnetic Resonance Spectroscopy
Creatine Kinase
Magnesium
Thulium
Enzymes
Adenosine Triphosphate
Phosphates
Ethane
Ventricular Pressure
Calcium Channels
Reperfusion
Sodium
Calcium
Acids

Keywords

  • Cytosolic free calcium concentration
  • Intracellular sodium concentration
  • Myocardial ischemia
  • Nuclear magnetic resonance
  • Preconditioning

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Steenbergen, C. J., Perlman, M. E., London, R. E., & Murphy, E. (1993). Mechanism of preconditioning: Ionic alterations. Circulation Research, 72(1), 112-125.

Mechanism of preconditioning : Ionic alterations. / Steenbergen, Charles Jr; Perlman, Michael E.; London, Robert E.; Murphy, Elizabeth.

In: Circulation Research, Vol. 72, No. 1, 01.1993, p. 112-125.

Research output: Contribution to journalArticle

Steenbergen, CJ, Perlman, ME, London, RE & Murphy, E 1993, 'Mechanism of preconditioning: Ionic alterations', Circulation Research, vol. 72, no. 1, pp. 112-125.
Steenbergen CJ, Perlman ME, London RE, Murphy E. Mechanism of preconditioning: Ionic alterations. Circulation Research. 1993 Jan;72(1):112-125.
Steenbergen, Charles Jr ; Perlman, Michael E. ; London, Robert E. ; Murphy, Elizabeth. / Mechanism of preconditioning : Ionic alterations. In: Circulation Research. 1993 ; Vol. 72, No. 1. pp. 112-125.
@article{3fa24a534d1f463eab75f9909015019a,
title = "Mechanism of preconditioning: Ionic alterations",
abstract = "The mechanism by which preconditioning (brief intermittent periods of ischemia and reflow) improves recovery of function and reduces enzyme release after a subsequent 30-minute period of ischemia was investigated in perfused rat hearts. Specifically, it was hypothesized that ischemia after preconditioning would result in a decreased production of H+ and therefore a smaller rise in [Na+]i and [Ca2+]i via Na+-H+ and Na+-Ca2+ exchange. To test this hypothesis we measured pHi, [Na+]i, [Ca2+]i, and cell high-energy phosphates during ischemia and reflow, and we correlated this with recovery of contractile function and release of creatine kinase during reflow. 31P nuclear magnetic resonance (NMR) was used to measure pHi and cell phosphates. [Na+]i was measured by 23Na NMR using the shift reagent thulium 1,4,7,10-tetraazacyclododecane-N,N,′N″,N‴- tetramethylenephosphonate to distinguish intracellular from extracellular sodium. [Ca2+]i was measured by 19F NMR using hearts loaded with 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N′,N′-tetraacetic acid, termed 5F-BAPTA. Basal time-averaged levels of pHi, [Na+]i, and [Ca2+]i were 7.07±0.08, 9.4±0.8 mM, and 715±31 nM, respectively. After 30 minutes of ischemia, in preconditioned hearts, PHi was 6.5±0.06, [Na+]i was 20.9±4.4 mM, [Ca2+]i was 2.1±0.4 μM, and ATP was negligible. In untreated hearts, after 30 minutes of ischemia, pH, was 6.3±0.08, [Na+]i was 26.7±3.8 mM, [Ca2+]i was 3.2±0.6 μM, and ATP was undetectable. During reperfusion after 30 minutes of ischemia, preconditioned hearts had significantly better recovery of contractile function than untreated hearts (71±9{\%} versus 36±8{\%} initial left ventricular developed pressure), and after 60 minutes of ischemia, preconditioned hearts had significantly less release of the intracellular enzyme creatine kinase (102±12 versus 164±17 IU/g dry wt). We also found that unpreconditioned hearts arrested with 16 mM MgCl2 (to inhibit calcium entry via calcium channels and Na+-Ca2+ exchange) before 30 minutes of ischemia recover function on reflow to the same extent as preconditioned hearts with or without magnesium arrest. Thus, preconditioning has no additional benefit in addition to magnesium arrest. In addition, in hearts that received 16 mM MgCl2 just before the 30-minute period of ischemia, preconditioning had no effect on the rise in [Ca2+]i during the 30-minute period of ischemia. These data support the hypothesis that preconditioning attenuates the increase in [Ca2+]i, [Na+]i, and [H+]i during ischemia, most likely because of reduced stimulation of Na+-H+ and Na+-Ca2+ exchange. The data suggest that interventions that minimize ionic derangements during ischemia are associated with improved recovery of contractility and less enzyme release on reflow.",
keywords = "Cytosolic free calcium concentration, Intracellular sodium concentration, Myocardial ischemia, Nuclear magnetic resonance, Preconditioning",
author = "Steenbergen, {Charles Jr} and Perlman, {Michael E.} and London, {Robert E.} and Elizabeth Murphy",
year = "1993",
month = "1",
language = "English (US)",
volume = "72",
pages = "112--125",
journal = "Circulation Research",
issn = "0009-7330",
publisher = "Lippincott Williams and Wilkins",
number = "1",

}

TY - JOUR

T1 - Mechanism of preconditioning

T2 - Ionic alterations

AU - Steenbergen, Charles Jr

AU - Perlman, Michael E.

AU - London, Robert E.

AU - Murphy, Elizabeth

PY - 1993/1

Y1 - 1993/1

N2 - The mechanism by which preconditioning (brief intermittent periods of ischemia and reflow) improves recovery of function and reduces enzyme release after a subsequent 30-minute period of ischemia was investigated in perfused rat hearts. Specifically, it was hypothesized that ischemia after preconditioning would result in a decreased production of H+ and therefore a smaller rise in [Na+]i and [Ca2+]i via Na+-H+ and Na+-Ca2+ exchange. To test this hypothesis we measured pHi, [Na+]i, [Ca2+]i, and cell high-energy phosphates during ischemia and reflow, and we correlated this with recovery of contractile function and release of creatine kinase during reflow. 31P nuclear magnetic resonance (NMR) was used to measure pHi and cell phosphates. [Na+]i was measured by 23Na NMR using the shift reagent thulium 1,4,7,10-tetraazacyclododecane-N,N,′N″,N‴- tetramethylenephosphonate to distinguish intracellular from extracellular sodium. [Ca2+]i was measured by 19F NMR using hearts loaded with 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N′,N′-tetraacetic acid, termed 5F-BAPTA. Basal time-averaged levels of pHi, [Na+]i, and [Ca2+]i were 7.07±0.08, 9.4±0.8 mM, and 715±31 nM, respectively. After 30 minutes of ischemia, in preconditioned hearts, PHi was 6.5±0.06, [Na+]i was 20.9±4.4 mM, [Ca2+]i was 2.1±0.4 μM, and ATP was negligible. In untreated hearts, after 30 minutes of ischemia, pH, was 6.3±0.08, [Na+]i was 26.7±3.8 mM, [Ca2+]i was 3.2±0.6 μM, and ATP was undetectable. During reperfusion after 30 minutes of ischemia, preconditioned hearts had significantly better recovery of contractile function than untreated hearts (71±9% versus 36±8% initial left ventricular developed pressure), and after 60 minutes of ischemia, preconditioned hearts had significantly less release of the intracellular enzyme creatine kinase (102±12 versus 164±17 IU/g dry wt). We also found that unpreconditioned hearts arrested with 16 mM MgCl2 (to inhibit calcium entry via calcium channels and Na+-Ca2+ exchange) before 30 minutes of ischemia recover function on reflow to the same extent as preconditioned hearts with or without magnesium arrest. Thus, preconditioning has no additional benefit in addition to magnesium arrest. In addition, in hearts that received 16 mM MgCl2 just before the 30-minute period of ischemia, preconditioning had no effect on the rise in [Ca2+]i during the 30-minute period of ischemia. These data support the hypothesis that preconditioning attenuates the increase in [Ca2+]i, [Na+]i, and [H+]i during ischemia, most likely because of reduced stimulation of Na+-H+ and Na+-Ca2+ exchange. The data suggest that interventions that minimize ionic derangements during ischemia are associated with improved recovery of contractility and less enzyme release on reflow.

AB - The mechanism by which preconditioning (brief intermittent periods of ischemia and reflow) improves recovery of function and reduces enzyme release after a subsequent 30-minute period of ischemia was investigated in perfused rat hearts. Specifically, it was hypothesized that ischemia after preconditioning would result in a decreased production of H+ and therefore a smaller rise in [Na+]i and [Ca2+]i via Na+-H+ and Na+-Ca2+ exchange. To test this hypothesis we measured pHi, [Na+]i, [Ca2+]i, and cell high-energy phosphates during ischemia and reflow, and we correlated this with recovery of contractile function and release of creatine kinase during reflow. 31P nuclear magnetic resonance (NMR) was used to measure pHi and cell phosphates. [Na+]i was measured by 23Na NMR using the shift reagent thulium 1,4,7,10-tetraazacyclododecane-N,N,′N″,N‴- tetramethylenephosphonate to distinguish intracellular from extracellular sodium. [Ca2+]i was measured by 19F NMR using hearts loaded with 1,2-bis(2-amino-5-fluorophenoxy)ethane-N,N,N′,N′-tetraacetic acid, termed 5F-BAPTA. Basal time-averaged levels of pHi, [Na+]i, and [Ca2+]i were 7.07±0.08, 9.4±0.8 mM, and 715±31 nM, respectively. After 30 minutes of ischemia, in preconditioned hearts, PHi was 6.5±0.06, [Na+]i was 20.9±4.4 mM, [Ca2+]i was 2.1±0.4 μM, and ATP was negligible. In untreated hearts, after 30 minutes of ischemia, pH, was 6.3±0.08, [Na+]i was 26.7±3.8 mM, [Ca2+]i was 3.2±0.6 μM, and ATP was undetectable. During reperfusion after 30 minutes of ischemia, preconditioned hearts had significantly better recovery of contractile function than untreated hearts (71±9% versus 36±8% initial left ventricular developed pressure), and after 60 minutes of ischemia, preconditioned hearts had significantly less release of the intracellular enzyme creatine kinase (102±12 versus 164±17 IU/g dry wt). We also found that unpreconditioned hearts arrested with 16 mM MgCl2 (to inhibit calcium entry via calcium channels and Na+-Ca2+ exchange) before 30 minutes of ischemia recover function on reflow to the same extent as preconditioned hearts with or without magnesium arrest. Thus, preconditioning has no additional benefit in addition to magnesium arrest. In addition, in hearts that received 16 mM MgCl2 just before the 30-minute period of ischemia, preconditioning had no effect on the rise in [Ca2+]i during the 30-minute period of ischemia. These data support the hypothesis that preconditioning attenuates the increase in [Ca2+]i, [Na+]i, and [H+]i during ischemia, most likely because of reduced stimulation of Na+-H+ and Na+-Ca2+ exchange. The data suggest that interventions that minimize ionic derangements during ischemia are associated with improved recovery of contractility and less enzyme release on reflow.

KW - Cytosolic free calcium concentration

KW - Intracellular sodium concentration

KW - Myocardial ischemia

KW - Nuclear magnetic resonance

KW - Preconditioning

UR - http://www.scopus.com/inward/record.url?scp=0027201253&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0027201253&partnerID=8YFLogxK

M3 - Article

C2 - 8380259

AN - SCOPUS:0027201253

VL - 72

SP - 112

EP - 125

JO - Circulation Research

JF - Circulation Research

SN - 0009-7330

IS - 1

ER -