The role of magnesium in the endothelial dysfunction caused by global ischemia followed by reperfusion: in vitro study of canine coronary arteries

Objective—To study the role of magnesium in the endothelial dysfunction of canine coronary arteries caused by cardiopulmonary bypass (CPB) global ischemia followed by reperfusion. Design—Segments of canine coronary arteries were suspended in organ chambers to measure isometric contraction by prostaglandin F 2α , and relaxed by acetylcholine (ACh), sodium fluoride (NaF), calcium ionophore (A 23187 ) and sodium nitroprusside (SNP) in crescent concentrations. The investigation protocol had groups with six dogs: CONTROL group (without CPB), CPB group (105 min of CPB without aortic cross‐clamping), ISCH group (45 min of CPB with aortic cross‐clamping), ISCH/REP group (45 min of aortic cross‐clamping followed by 60 min of reperfusion). The coronary relaxations were evaluated with (phase I), without (phase II) and restored magnesium (phase III) to the organ bath. Results—The presence of magnesium in the organ bath was associated with the greater relaxation in response to agonists of the nitric oxide production. ...