Phosphorylation potential and adenosine release during norepinephrine infusion in guinea pig heart.
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)
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Department of Physiology, Michigan State University, East Lansing 48824.
Wangler
R D
RD
Dillon
P F
PF
Romig
G D
GD
Sparks
H V
HV
D000241:Adenosine / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology*; D010766:Phosphorylation; D012016:Reference Values
D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000241:Adenosine; D009638:Norepinephrine