A gating 31P NMR method triggered by pulses for cardiac pacing.
A new gating NMR technique triggered by pulses for the cardiac pacing of isolated, perfused rat heart is described. This technique is suitable for obtaining spectra at the same positions over the cardiac cycle with the same RF pulse repetition time and with constant heart rate. Accordingly, each recovered magnetization level at these positions during the cycle can be kept constant. It also allows a qualitative analysis of the myocardial energy level during the cycle under the condition of the same or different cardiac workload (rate pressure product, HR x LVP). This method was used to observe cyclical changes in the concentration of adenosine triphosphate (ATP), phosphocreatine (PCr), P(i), and in pH during the cardiac cycle, and confirmed that the levels of ATP and PCr showed reversible decreases, and P(i) showed an antiphasic increase at the peak systole. On the other hand, no significant changes in pH were noted during the cardiac cycle. This pacing-gated technique is an improvement over other gated NMR techniques triggered by the blood pressure or by ECG traces.
Tanaka
K
K
Central Laboratory for Research and Education, Asahikawa Medical College, Japan.
Honda
H
H
Akita
N
N
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002304:Cardiac Pacing, Artificial; D006329:Heart Conduction System / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D009206:Myocardium / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism; D011674:Pulse; D051381:Rats; D017208:Rats, Wistar
D010725:Phosphocreatine; D010758:Phosphorus; D000255:Adenosine Triphosphate