Multiple quantum filtered 23Na NMR spectroscopy in the perfused heart

Area of Science:

• Biophysics
• Cardiovascular Research
• Nuclear Magnetic Resonance (NMR) Spectroscopy

Background:

• Distinguishing intracellular and extracellular sodium (Na+) in vivo is crucial for understanding cell function and disease.
• Multiple Quantum Filtered (MQF) 23Na NMR spectroscopy has been proposed as a non-toxic method for this differentiation.
• Previous studies lacked definitive validation of the spatial origin of MQF 23Na NMR signals.

Purpose of the Study:

• To investigate the origin of MQF 23Na NMR signals in perfused rat hearts.
• To determine whether MQF 23Na NMR can reliably distinguish between intra- and extracellular sodium compartments in vivo.
• To assess the influence of ischemia on sodium compartment signals.

Main Methods:

• Utilized perfused rat hearts for in vivo NMR experiments.
• Employed shift reagents to selectively label and differentiate extracellular sodium signals.
• Applied MQF 23Na NMR spectroscopy to analyze sodium distribution under normal and ischemic conditions.

Main Results:

• The MQF 23Na NMR signal predominantly originated from the extracellular space in normal hearts.
• In ischemic hearts, the MQF signal shifted to originate primarily from the intracellular space.
• The quenching effect of shift reagents potentially obscured some extracellular signals, particularly during ischemia.

Conclusions:

• MQF 23Na NMR spectroscopy shows potential for distinguishing between intracellular and extracellular sodium in vivo.
• The spatial origin of the MQF signal is sensitive to the physiological state of the heart, shifting from extracellular to intracellular during ischemia.
• Further investigation is needed to fully characterize signal origins and account for potential signal masking by shift reagents.