Robitaille P M, Merkle H, Sako E, Lang G, Clack R M, Bianco R, From A H, Foker J, Uğurbil K
Department of Biochemistry, University of Minnesota, Navarre 55392.
Magn Reson Med. 1990 Jul;15(1):8-24. doi: 10.1002/mrm.1910150103.
The ability to measure ATP synthesis rates using 31P-NMR spectroscopy is demonstrated in the normal, ischemic, and postischemic myocardium in vivo. Cardiopulmonary bypass (CBP) was employed to induce 20 min of global myocardial ischemia, and to conduct magnetization transfer measurements during the ischemic episode and following reperfusion and return to normal circulation. For the first few minutes of ischemia, transfer of magnetization from ATP gamma to Pi was extensive and the resultant fractional reduction (delta M/M0) in the Pi resonance intensity reached approximately 100%. Subsequent to reperfusion and stabilization off CPB and on normal circulation, both the fractional reduction and the spin-lattice relaxation time, T1*, of the Pi resonance were determined when ATP gamma spins were saturated. Under these conditions, the unidirectional ATP synthesis rate was 0.41 +/- 0.09 (SEM, N = 4) mumol/s/g wet wt. The data suggest that in the canine myocardium in vivo, glycolytic enzymes mediate a very rapid exchange between Pi and ATP gamma-phosphates during early phases of ischemia; in the postischemic reperfused myocardium, however, the glycolytic contribution to the unidirectional Pi----ATP rate measured by NMR in vivo is relatively small compared to that observed in glucose-perfused, postischemic rat hearts.
利用31P - NMR光谱法测量ATP合成速率的能力在正常、缺血和缺血后心肌的体内实验中得到了证实。采用体外循环（CBP）诱导20分钟的全心肌缺血，并在缺血期、再灌注期以及恢复正常循环期间进行磁化转移测量。在缺血的最初几分钟内，磁化从ATPγ向Pi的转移非常广泛，Pi共振强度的分数降低（δM/M0）达到约100%。在再灌注、脱离CBP并稳定在正常循环后，当ATPγ自旋饱和时，测定Pi共振的分数降低和自旋晶格弛豫时间T1*。在这些条件下，单向ATP合成速率为0.41±0.09（标准误，N = 4）μmol/s/g湿重。数据表明，在犬类心肌的体内实验中，糖酵解酶在缺血早期介导了Pi与ATPγ - 磷酸之间非常快速的交换；然而，在缺血后再灌注的心肌中，与在葡萄糖灌注的缺血后大鼠心脏中观察到的情况相比，糖酵解对通过NMR在体内测量的单向Pi→ATP速率的贡献相对较小。
