Naloxone prevents increased atrial natriuretic peptide release during regional myocardial ischaemia and stunning in awake dogs.
BACKGROUND
Atrial natriuretic peptide (ANP) release is increased in patients with ischaemic left ventricular dysfunction. A beneficial effect of naloxone on recovery from myocardial stunning was shown previously. The aim of this study was to investigate the effects of naloxone on ANP release during regional myocardial ischaemia and stunning in awake dogs.


METHODS
Ten dogs were chronically instrumented for measurement of heart rate, left atrial, aortic, and left ventricular pressure (LVP), LV dP x dtmax/min(-1), and myocardial wall-thickening fraction. An occluder around the left anterior descending artery (LAD) allowed induction of reversible ischaemia in the LAD-perfused myocardium. Each dog underwent two ischaemic episodes (randomized crossover fashion; separate days): 10 min of LAD occlusion (1) after application of naloxone (63 microg kg(-1)), and (2) without naloxone. ANP levels were measured at baseline (BL) and at predetermined time points until complete recovery of myocardial stunning occurred.


RESULTS
LAD ischaemia-induced release of ANP (peak level: 182 (30) vs 27 (7) pg ml(-1) BL) only in the control group without naloxone. Between 1 and 180 min of reperfusion, ANP levels were significantly higher only in the control group (P<0.05).


CONCLUSIONS
Pre-ischaemic application of naloxone prevents this ischaemia-induced ANP-release in conscious dogs.
Weber
T P
TP
Klinik und Poliklinik für Anästhesiologie und Operative Intensivmedizin, Westfälische Wilhelms-Universität Münster, Germany.
Raufbake
C
C
Grosse Hartlage
M A
MA
Rolf
N
N
Stypmann
J
J
Van Aken
H
H
Berendes
E
E
Meissner
A
A
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood*; D001783:Blood Flow Velocity / Q000187:drug effects; D018592:Cross-Over Studies; D004285:Dogs; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D017202:Myocardial Ischemia / Q000097:blood*; D017682:Myocardial Stunning / Q000097:blood; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D020097:Natriuretic Peptide, Brain / Q000097:blood
D009292:Narcotic Antagonists; D020097:Natriuretic Peptide, Brain; D009270:Naloxone; D009320:Atrial Natriuretic Factor