| Autor: |
Stoll, H., Bay, W., Vogel, W., Özbek, C., Hanser, A., Schieffer, H., Harbauer, G. |
| Zdroj: |
Basic Research in Cardiology; Jul1994, Vol. 89 Issue 4, p354-365, 12p |
| Abstrakt: |
Purpose: The purpose of the study was to verify that theRubidium/krypton (Rb/Kr) method allows the quantitative measurement of myocardial perfusion. Principle: The potassium analogous cationRb is accumulated in the myocardium by the cell membrane-bound Na−K-ATPase. After accumulation an intracellular equilibrium establishes betweenRb and its radioactive daughter nuclideKr. The flow-sensitive method evaluates the disturbance of this equilibrium by perfusion which washes out the short-lived diffusable daughter nuclideKr while the mother nuclideRb remains cell-bound. Methods: Isolated rabbit hearts were prepared in a modified Langendorff technique which allowed quantitative collection of the coronary sinus efflux. The myocardium was labeled with pureRb by bolus injection into the aortic cannula. Spectroscopic measurements ofRb andKr gamma radiation were performed using a germanium detector. Perfusion was varied in the range between 0 and 4 ml/min/g. The activity ratioRb/Kr was determined and compared with coronary sinus effusion. Results: Rb/Kr activity ratio was closely related (r=0.98) to perfusion as described by the predicted equation Rb/Kr=(F/2.96 P)+1. (Rb/Kr=activity ratio betweenRb andKr in the myocardium; F=myocardial perfusion (ml/min/g); P=partition coefficient (myocardium/perfusate) for Krypton gas.) The constant P was found to be 1.14±0.06 (mean±SEM). No saturation of this ratio at high flow rates was observed. Conclusion: The activity ratioRb/Kr is a valid quantitative measure for myocardial perfusion in isolated hearts. The main limitation of the method before application in man is the correction of the different gamma ray tissue absorption of both nuclides. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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