Myocardial kinetics of carbon-11-epinephrine in the isolated working rat heart
- Univ. of Michigan, Ann Arbor, MI (United States); and others
The kinetics of EPI were studied in the isolated rat heart model to evaluate {sup 11}C-epinephrine (EPI) as a radiotracer for the assessment of sympathetic neuronal function in the heart. Isolated rat hearts were perfused in a working mode. Carbon-11-EPI was added to the perfusate during wash-in period of 20 min, followed by a washout period of 40 min. Radioactivity in the heart was externally monitored and time-activity curves were recorded as a function of time. Effluent samples were collected throughout each study to determine the fraction of {sup 11}C radioactivity as intact tracer. Time-activity curves of control hearts showed that {sup 11}C-EPI is taken up and retained by the myocardium. Desipramine inhibition (DMI) of uptake-1 resulted in a significant decrease in myocardial uptake and retention of {sup 11}C-EPI by 91% compared to controls. Addition of DMI to the perfusion medium during washout did not affect kinetics of {sup 11}C-EPI compared to control hearts. Reserpine pretreated rat hearts also showed significant decrease in tracer retention of 95% compared to controls. The metabolic data showed that, in control conditions, about 61% of {sup 11}C-EPI taken up by the rat heart is rapidly metabolized and released. Carbon-11-EPI traces sympathetic nerve terminals in the isolated rat heart. Uptake blockade by DMI and reserpine suggest that uptake and storage of {sup 11}C-EPI appear to be similar to that of norepinephrine. However, the prominent metabolic pathway warrants further consideration. These results suggest that {sup 11}C-EPI may be a suitable radiolabeled tracer for the evaluation of sympathetic vesicular function of the heart by PET. 23 refs., 3 figs., 3 tabs.
- DOE Contract Number:
- FG02-90ER61091
- OSTI ID:
- 471493
- Journal Information:
- Journal of Nuclear Medicine, Journal Name: Journal of Nuclear Medicine Journal Issue: 5 Vol. 38; ISSN 0161-5505; ISSN JNMEAQ
- Country of Publication:
- United States
- Language:
- English
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