Phosphorus J coupling constants of ATP in human myocardium and calf muscle.
Proton-decoupled 31P NMR spectroscopy of the heart and calf muscle of healthy volunteers was performed with a 1.5 T whole-body imager. By use of two-dimensional chemical-shift imaging in combination with slice-selective excitation, well-resolved localized spectra (elements of 38 ml) were obtained within 20 to 35 min from which the homonuclear J coupling constants of ATP could be determined. In myocardium, J gamma beta = 16.03 +/- 0.17 Hz and J alpha beta = 15.82 +/- 0.23 Hz were obtained, while the values in calf muscle were J gamma beta = 17.16 +/- 0.12 Hz and J alpha beta = 16.04 +/- 0.09 Hz. The difference in J gamma beta was significant. According to the literature, a possible reason for greater ATP J coupling constants is a smaller fraction of ATP complexed to magnesium. However, the chemical-shift difference between alpha- and beta-ATP, which is also a measure for the fraction of ATP complexed to magnesium, showed only a small difference in ATP complexation: 88% in myocardium and 90% in calf muscle. This small difference cannot account for the observed difference in J gamma beta.
Jung
W I
WI
Hypertension and Diabetes Research Unit, Max Grundig Clinic, Bühl, Germany.
Widmaier
S
S
Seeger
U
U
Bunse
M
M
Staubert
A
A
Sieverding
L
L
Straubinger
K
K
van Erckelens
F
F
Schick
F
F
Dietze
G
G
Lutz
O
O
D000255:Adenosine Triphosphate / Q000032:analysis*; D000293:Adolescent; D000328:Adult; D002614:Chelating Agents / Q000032:analysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007089:Image Enhancement; D008274:Magnesium / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D018482:Muscle, Skeletal / Q000737:chemistry*; D009206:Myocardium / Q000737:chemistry*; D010725:Phosphocreatine / Q000032:analysis; D010758:Phosphorus / Q000032:analysis*; D012815:Signal Processing, Computer-Assisted
D002614:Chelating Agents; D010725:Phosphocreatine; D010758:Phosphorus; D000255:Adenosine Triphosphate; D008274:Magnesium