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Contribution of mitochondria to cardiac muscle water/macromolecule proton magnetization transfer

Kathleen Ward1, Adam E Schussheim, Robert S Balaban

  • 1Laboratory of Cardiac Energetics, National Heart Lung and Blood Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20817, USA.

Magnetic Resonance in Medicine
|December 4, 2003
PubMed

Insights

Mitochondria macromolecules significantly contribute to proton magnetization transfer (MT) in heart tissue. Their structure is not critical, as isolated mitochondria show similar MT effects to intact tissue.

Area of Science:

  • Biophysics
  • Biochemistry
  • Cardiovascular Science

Background:

  • Proton magnetization transfer (MT) is a biophysical process crucial for understanding water-macromolecule interactions in biological tissues.
  • Mitochondria are vital organelles within cells, playing key roles in cellular respiration and energy production.
  • The specific contribution of mitochondria to the overall MT effects in complex tissues like the heart remains incompletely understood.

Purpose of the Study:

  • To quantify the contribution of mitochondria to water-macromolecule proton magnetization transfer (MT) in porcine heart tissue.
  • To investigate the role of mitochondrial structure in MT effects.
  • To determine if mitochondrial macromolecules are a significant source of MT in the intact heart.

Main Methods:

  • Proton MT imaging was performed on intact porcine heart tissue.
  • MT effects of isolated porcine mitochondria in suspension were measured at physiological concentrations.
  • Mitochondrial structure was disrupted using freeze-thaw cycles and detergent treatment to assess their impact on MT.

Main Results:

  • Isolated mitochondria exhibited MT effects comparable in magnitude and bandwidth to those observed in intact heart tissue.
  • Disruption of mitochondrial structure led to only minor decreases (approximately 25%) in MT effects.
  • These findings indicate that the macromolecular content of mitochondria, rather than their intact structure, is primarily responsible for their MT contribution.

Conclusions:

  • Mitochondrial macromolecules are a significant contributor to the overall water-macromolecule proton magnetization transfer (MT) in intact heart tissue.
  • The structural integrity of mitochondria is not essential for their substantial contribution to MT.
  • This study highlights the importance of considering mitochondrial contributions when interpreting MT imaging data of cardiac tissue.

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