Journal of Applied Physiology, Vol 74, Issue 4 1549-1554, Copyright © 1993 by American Physiological Society
31P-NMR spectroscopy of isolated perfused rat lung
Y. Hayashi, T. Inubushi, S. Nioka and R. E. Forster
Department of Physiology, School of Medicine, University of Pennsylvania, Philadelphia 19104.
We obtained 202.5-MHz 31P-nuclear magnetic resonance (NMR) spectra of
isolated perfused rat lungs, degassed and inflated, and of lung extract.
The spectra included those of ATP, ADP, phosphocreatine (PCr), inorganic
phosphate (Pi), phosphomonoesters, phosphodiesters, and a broad component
due to the membrane phospholipids. The line width at one-half peak height
for beta-ATP was 1.0 ppm for the degassed lung and 1.2 ppm for the inflated
lung. This suggests that the air-water interfaces in inflated lung, which
produce proton NMR line broadening, do not act prominently in 31P-NMR
spectroscopy. In a degassed lung, when perfusion was stopped for up to 30
min, PCr and ATP peaks decreased progressively with time while Pi and
phosphomonoester peaks increased. On return of flow, these changes
reversed. The intracellular pH values calculated from the difference in
magnetic field between PCr and Pi peaks of inflated and degassed lungs were
7.16 +/- 0.10 (SD; n = 4) and 6.99 +/- 0.10 (n = 4), respectively. The
change of intracellular pH caused by 30 min of ischemia was -0.2 pH units.
Our findings indicate that air-water interfaces should not broaden lung 31P
peaks in vivo.
