Intracoronary magnesium is not protective against acute reperfusion injury in the regional ischaemic-reperfused dog heart.
Intravenous magnesium lowers mortality in patients with suspected myocardial infarction. We tested the hypothesis that the protective effect may be due to a direct, local influence of magnesium on myocardial reperfusion injury in a dog model of ischaemia/reperfusion. Ten anaesthetized open chest dogs underwent 1 h of left anterior descending artery (LAD) occlusion and 6 h of reperfusion. The animals received intracoronary (i.c.) magnesium aspartate (Mg, n = 5) or vehicle infusion (n = 5) for the first hour of reperfusion. Mg infusion was adapted to actual LAD flow (ultrasonic flow probe) to increase regional plasma concentration by 4 mmol L-1. Regional myocardial function was measured as percent systolic wall thickening (sWTh, sonomicrometry). Intracoronary Mg increased LAD flow during application (at 15 min reperfusion; Mg, 194 +/- 44 (mean +/- SD); control, 116 +/- 41 mL min-1 100 g-1, P < 0.01). sWTh decreased during coronary occlusion from 14.3 +/- 7.1% to -4.7 +/- 2.7% in the control group and from 14.8 +/- 2.5% to -4.1 +/- 3.1% in the Mg group. Throughout the reperfusion period wall function remained depressed in both groups to a similar degree (control, -3.5 +/- 1.8%; Mg, -3.0 +/- 1.9% at 6 h reperfusion). Global haemodynamics were not different. Infarct size after 6 h reperfusion (TTC staining) was similar in both groups (Mg, 20.6 +/- 5.0; control, 24.4 +/- 8.7% of area at risk). Regional magnesium application (i.c.) to post-ischaemic reperfused myocardium had no influence on infarct size or post-ischaemic regional wall function in this model.(ABSTRACT TRUNCATED AT 250 WORDS)
Schlack
W
W
Abt. für Herz- und Kreislaufphysiologie, Heinrich-Heine-Universität, Dusseldorf, Germany.
Bier
F
F
Schäfer
M
M
Uebing
A
A
Schäfer
S
S
Borchard
U
U
Thämer
V
V
D000818:Animals; D001224:Aspartic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D003326:Coronary Circulation; D003331:Coronary Vessels; D004285:Dogs; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007263:Infusions, Parenteral; D008297:Male; D009203:Myocardial Infarction / Q000473:pathology / Q000503:physiopathology; D015428:Myocardial Reperfusion Injury / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D010101:Oxygen Consumption / Q000187:drug effects
D001224:Aspartic Acid