Cellular response to reperfused oxygen in the postischemic
myocardium.
Chung, Youngran, and Thomas Jue.
Biological Chemistry Department, University of California Davis,
Davis, CA 95616-8635
APStracts 3:0015H, 1996.
Perfused rat heart experiments focused on determining the critical
oxygen level in postischemic myocardium. After a 20 min global
ischemia, reperfusion began with oxygen saturated, saline buffer
reflowing at different rates (0.5-12 ml/min). The 1H NMR signal of
the Val E11 Mb gave an index of the intracellular oxygenation, while
the 31P NMR spectra reflected the high energy phosphate and pH
status. At the same time, physiological monitors recorded both
contractile function and oxygen consumption. Biochemical analysis
determined the lactate concentration. Within 6-12 minutes of
reperfusion, the O2 reached a new steady state, which depended
directly on the flow rate. Below 12ml/min reflow, the postischemic O2
level was consistently lower than the corresponding control values.
PCr, Pi, pH, MVO2, and lactate formation rate exhibited similar
linear relationship with MbO2 saturation in both the control and
postischemic myocardium. It appears that neither the cellular energy
production nor the steep intracellular oxygen gradient has changed
substantially in the postischemic myocardium.
Received 17 April 1995; accepted in final form 19 December 1995.
APS Manuscript Number H366-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96