Local release of myocardial norepinephrine during acute ischemia: an experimental study in the isolated perfused rat heart.
The appearance of an early ischemia-induced local release of myocardial norepinephrine (NE) was examined in the isolated Langendorff-perfused rat heart prelabeled with [3H]NE. Either glucose or lactate was used as the perfusion substrate. Ischemia for a 60-min period was produced by global flow reduction (by 90%) or left coronary artery ligation followed by a 15-min reperfusion period. During the first 20 min of ischemia both the concentration of [3H]NE and the fraction of total 3H representing nonmetabolized [3H]NE were increased in the coronary venous effluent. This early increase in [3H]NE concentration was most pronounced in hearts with global ischemia perfused with lactate as substrate (from 19 +/- 2 to 524 +/- 76 fmol/ml/g after 20 min of ischemia). The quantity of [3H]NE released was then further increased during the 60-min period of ischemia. Reperfusion of the ischemic myocardium was associated with a marked outflow of [3H]NE and [3H]NE metabolites, primarily representing a washout from the ischemic tissue. Under the present experimental conditions the ischemia-induced release of NE was attenuated by glucose, probably owing to an ongoing glycolytic ATP formation. This effect was most pronounced during global low-flow ischemia. It is concluded that ischemia is associated with a local release of myocardial NE. In the nonworking Langendorff heart preparation, clear evidence of such a local release was already obtained after 10-20 min of ischemia.
L
L
Carlsson
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T
Abrahamsson
O
O
Almgren
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003326:Coronary Circulation; D003327:Coronary Disease / Q000378:metabolism*; D066298:In Vitro Techniques; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000097:blood / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D001786:Blood Glucose; D007773:Lactates; D019344:Lactic Acid; D009638:Norepinephrine