AJP - Heart and Circulatory Physiology, Vol 253, Issue 5 1184-H1191, Copyright © 1987 by American Physiological Society
Phosphorylation potential and adenosine release during norepinephrine infusion in guinea pig heart
M. X. He, R. D. Wangler, P. F. Dillon, G. D. Romig and H. V. Sparks
Department of Physiology, Michigan State University, East Lansing 48824.
This study tested the hypothesis that adenosine released from isolated
guinea pig hearts (n = 5) in response to norepinephrine is related to the
cellular phosphorylation potential (PP; [ATP]/[ADP][Pi]), where Pi is
inorganic phosphate. 31P-nuclear magnetic resonance (NMR) was used to
measure the relative concentrations of Pi, phosphocreatine (PCr), and ATP.
Hearts were Langendorff perfused with a physiological salt solution
containing 0.1 mM Pi. The venous effluent was collected for measurement of
adenosine and partial pressure of oxygen (PO2). After a control period,
norepinephrine (6 X 10(-8) M) was infused for 20 min during which 31P-NMR
spectra and samples of venous effluent were collected every minute. With
norepinephrine infusion, PCr decreased rapidly to 72% of control (P less
than 0.05) by 8 min and then recovered to 80% of control for the remaining
12 min. ATP fell slowly to 70% of control (P less than 0.01) over 20 min.
Pi increased to a peak at 2 min (P less than 0.01), then declined slowly to
a steady state (60% of the peak and 3.5 X control) from 8 to 20 min.
Adenosine release increased from 11 +/- 6 to a peak of 250 +/- 68
pmol.min-1.g-1 (P less than 0.01) at 7 min and then slowly fell (P less
than 0.05) to a steady state of approximately 110 pmol.min-1.g-1 (P less
than 0.01 vs. control) from 10 to 20 min.(ABSTRACT TRUNCATED AT 250 WORDS)
