AJP - Heart and Circulatory Physiology, Vol 253, Issue 5 1215-H1223, Copyright © 1987 by American Physiological Society
High-energy phosphates and function in isolated, working rabbit hearts
E. D. Lewandowski, Sr. Devous MD and R. L. Nunnally
Nuclear Medicine Center, University of Texas Health Science Center at Dallas 75235.
An isolated, working, rabbit heart has been developed for use with nuclear
magnetic resonance (NMR) spectroscopy. This model is functionally stable
over a 4-h period and displays classic hemodynamic responses to work-load
changes. Control 31P spectra of this preparation (n = 5) were obtained with
simultaneous recordings of left ventricular pressure (LVP), LVP
differentiated with respect to time (dP/dt), heart rate (HR), and cardiac
output (CO). ATP, phosphocreatine (PCr), and hemodynamics remained stable
over a 90-min perfusion. Hearts were also subjected to 13.5 min of global
ischemia (IS) at 37 degrees C followed by 60 min of reperfusion (RE, n = 7)
or 45 min of chronic IS (n = 6). Contraction ceased within 60 s of IS. PCr
loss was rapid, reaching undetectable limits by 11 min. ATP loss was
gradual and bore no relationship to functional loss. ATP fell to 60 +/- 4%
(means +/- SE) of pre-IS levels after 13.5 min of IS. With RE, PCr returned
to control levels, whereas ATP values remained depressed for the entire 60
min. Functional activity resumed with RE, but dP/dt did not rise above 85
+/- 7% of preischemic values. No correlation between residual ATP at the
end of IS and functional recovery during RE was evident.
