Nadir Askenasy

Optimal level of hypothermia for prolonged myocardial protection assessed by 31P nuclear magnetic resonance.

The optimal level of hypothermia during myocardial preservation for cardiac transplantation is not known. Phosphorus 31 nuclear magnetic resonance spectroscopy was used to assess the effect of different preservation temperatures (15 degrees C in group 1, 4 degrees C in group 2) on the myocardial high-energy phosphate profiles during prolonged global ischemia and subsequent reperfusion of isolated rat hearts. Adenosine triphosphate depletion during ischemia was more gradual in group 2, leading to significant differences in myocardial adenosine triphosphate concentrations between the two groups after 3 hours of ischemia. The fall in intracellular pH during ischemia was significantly less pronounced in hearts preserved at 4 degrees C as compared with those at 15 degrees C. The postischemic recovery of both the left ventricular peak systolic pressure and the maximum rate of increase of left ventricular pressure was enhanced in group 2, although the ischemic period was 3 hours longer than in group 1. Hypothermia at 4 degrees C as compared with 15 degrees C appears to prolong myocardial protection with respect to adenosine triphosphate preservation, prevention of the fall in intracellular pH, and the enhancement of postischemic hemodynamic recovery.

Two-Dimensional 31P-1H Correlation Spectroscopy in Intact Organs and Their Extracts

2D 31P-1H correlation spectroscopy is a useful technique for the assignment of 31P-NMR resonances. It allows the separation of overlapping 31P peaks by spreading them in the 1H dimension and gives the chemical shifts of the protons which are spin-spin coupled to the phosphorus atoms. In this chapter we give a short survey of the various 2D heteronuclear techniques with an emphasis on those that might be useful for 31P-1H correlation in extracts, intact tissues, and in vivo. Examples are given for such applications in intact pancreases excised from healthy rats and from rats with experimental pancreatitis, in excised pancreatic carcinoma, as well as for extracts from rat pancreas and liver. The potential of 2D 31P-1H correlation spectroscopy for the study of isolated and in-vivo systems is discussed.