Adenosine Release and High Energy Phosphates in Intact Dog Hearts During Norepinephrine Infusion
作者:
Mark Gorman,
Xue-Han Ning,
Miao-Xiang He,
Michael Portman,
Harvey Sparks,
期刊:
Circulation Research
(OVID Available online 1992)
卷期:
Volume 70,
issue 6
页码: 1146-1151
ISSN:0009-7330
年代: 1992
出版商: OVID
关键词: 5'-nucleotidase;phosphocreatine;31P nuclear magnetic resonance spectroscopy;coronary circulation
数据来源: OVID
摘要:
Cardiac adenosine release is thought to depend on the oxygen supply/demand ratio, and this effect may be mediated by changes in high energy phosphate concentrations. Previous studies supporting this hypothesis have been done primarily in isolated hearts. We tested this hypothesis in intact dog hearts. Anesthetized, open-chest dogs were placed in a 4.7-T magnet where31P nuclear magnetic resonance spectra were acquired via a surface coil over the heart at 2-minute intervals (60 scans, 2-second interpulse delay). Coronary sinus flow was shunted through a flow probe and returned via a jugular vein. After a control period, intracoronary norepinephrine was infused (12 μg/min) for 16 minutes and plasma samples were taken every 5 minutes. The phosphocreatine/ATP peak area ratio was used as an index of high energy phosphate changes. During norepinephrine infusion, arterial pressure, heart rate, coronary sinus flow, oxygen consumption, and adenosine release all increased significantly. Adenosine release peaked at 5 minutes but remained elevated after 15 minutes. There was a transient fall in the phosphocreatine/ATP ratio (9.2±3.1%,p<0.05) during the first 7 minutes, but the ratio returned to control levels by 9 minutes. The oxygen supply/consumption ratio increased after 5 minutes of norepinephrine infusion and then returned to control levels. We conclude that during norepinephrine infusion in vivo, persistent adenosine release can occur with only small transient changes in high energy phosphate concentrations and with no decrease in the oxygen supply/demand ratio.
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