Serum magnesium and potassium in acute myocardial infarction: relationship to existing beta-blockade and infarct size.
Patients (n = 314) with acute myocardial infarction (AMI) were divided into three groups according to the time elapsed from onset of chest pain to when the first sample for determination of magnesium (s-Mg1) and potassium (s-K1) was drawn (A: hours 0-6; B: hours 6-10, and C: hours 10-24). Potassium and Mg were also measured in a second sample drawn three to twelve days (mean 6.3 days) later (s-Mg2, s-K2). Whereas s-Mg1 was lower than s-Mg2 in all three groups, s-K1 was reduced only in group A. Ten patients in group A receiving nonselective beta-blockers had an attenuated drop in s-Mg1, whereas the drop in s-K1 was completely inhibited. The differences between s-Mg2 and s-Mg1 (delta s-Mg) in all groups, and between s-K2 and s-K1 (delta s-K) in group A, increased with increasing mean peak creatine kinase (CKmax) levels to approximately 1300-1800 U/L. In conclusion, these observations suggest that the initial drop in s-Mg and s-K in the early phase of AMI is due to increased stimulation of beta 2-adrenergic receptors; these changes can be prevented partly or completely by the use of nonselective beta-blockers.
Landmark
K
K
Department of Internal Medicine, Ullevål University Hospital, Oslo, Norway.
Urdal
P
P
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008274:Magnesium / Q000097:blood*; D008297:Male; D009203:Myocardial Infarction / Q000097:blood* / Q000188:drug therapy / Q000473:pathology; D011188:Potassium / Q000097:blood*; D013997:Time Factors
D000319:Adrenergic beta-Antagonists; D008274:Magnesium; D011188:Potassium