Magnesium causes nitric oxide independent coronary artery vasodilation in humans.
OBJECTIVE
To determine how magnesium affects human coronary arteries and whether endothelium derived nitric oxide (EDNO) is involved in the coronary arterial response to magnesium.


METHODS
Quantitative coronary angiography and Doppler flow velocity measurements were used to determine the effects of the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA) on magnesium induced dilation of the epicardial and resistance coronary arteries.


METHODS
Hiroshima University Hospital a tertiary cardiology centre.


METHODS
17 patients with angiographically normal coronary arteries.


METHODS
Magnesium sulfate (MgSO(4)) (0.02 mmol/min and 0.2 mmol/min) was infused for two minutes into the left coronary ostium before and after intracoronary infusion of L-NMMA.


METHODS
Diameter of the proximal and distal segments of the epicardial coronary arteries and coronary blood flow.


RESULTS
At a dose of 0.02 mmol/min, MgSO(4) did not affect the coronary arteries. At a dose of 0.2 mmol/min, MgSO(4) caused coronary artery dilation (mean (SEM) proximal diameter 3.00 (0.09) to 3.11 (0.09) mm; distal 1.64 (0.06) to 1.77 (0.07) mm) and increased coronary blood flow (79.3 (7.5) to 101.4 (9.9) ml/min, p < 0.001 v baseline for all). MgSO(4) increased the changes in these parameters after the infusion of L-NMMA (p < 0.001 v baseline).


CONCLUSIONS
Magnesium dilates both the epicardial and resistance coronary arteries in humans. Furthermore, the coronary arterial response to magnesium is dose dependent and independent of EDNO.
Teragawa
H
H
The First Department of Internal Medicine, Hiroshima University School of Medicine, 1-2-3 Kasumi, Minamiku, Hiroshima, Japan 734-8851. teragawa@mcai.med.hiroshima-u.ac.jp
Kato
M
M
Yamagata
T
T
Matsuura
H
H
Kajiyama
G
G
D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D008278:Magnesium Sulfate / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000502:physiology; D014664:Vasodilation; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*; D019323:omega-N-Methylarginine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D014665:Vasodilator Agents; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D008278:Magnesium Sulfate