Atrial fibrillation after coronary artery bypass surgery: association with changes in G protein levels in mononuclear leukocytes.
Atrial fibrillation (AFib) is a frequent complication of coronary artery bypass grafting (CABG). Its cause, however, is unknown. As the adrenergic system is involved in some types of AFib, we hypothesized that a change in guanine nucleotide-binding protein (G protein) expression plays a role in the development of post-CABG AFib. In 28 patients undergoing CABG surgery, the G(s alpha)/G(i alpha) ratio (stimulatory/inhibitory G protein alpha) at the protein (Western blotting) and mRNA (reverse transcription polymerase chain reaction) levels was measured before and after surgery. As a suitable test system allowing multiple analysis mononuclear leukocytes (MNL) were chosen. The perioperative change of the G(s alpha)/G(i alpha) ratio of protein and mRNA was significantly different in patients who subsequently developed AFib (eight patients) and in patients who did not (20 patients; P<0.01 and <0.001, respectively). On average, the protein G(s alpha)/G(i alpha) ratio decreased from 1.79+/-1.13 (mean+/-SD) to 1.32+/-0.69 in patients without AFib (P=0.1, n.s.) whereas a significant increase from 0.86+/-0.44 to 1.62+/-0.65 (P<0.01) was observed in patients subsequently developing AFib. The mRNA G(s alpha)/G(i alpha) ratio decreased significantly from 0.53+/-0.24 to 0.36+/-0.11 in patients without AFib (P<0.01) whereas a significant increase from 0.31+/-0.14 to 0.47+/-0.13 was observed in those who subsequently developed AFib (P<0.05). These results indicate that an increase of the G(s alpha)/G(i alpha) ratio in MNL is associated with AFib after CABG surgery and possibly may be used as a prognostic indicator of this complication.
Tittelbach
V
V
Department of Clinical Pathology, Robert Bosch Krankenhaus, Stuttgart, Germany.
Schwab
M
M
Volff
J N
JN
Mörike
K
K
Lemke
P
P
Giray
J
J
Lee
P
P
Ratge
D
D
Hellberg
K
K
Wisser
H
H
D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology*; D015415:Biomarkers; D015153:Blotting, Western; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D005260:Female; D019204:GTP-Binding Proteins / Q000145:classification / Q000378:metabolism*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D015415:Biomarkers; D012333:RNA, Messenger; D019204:GTP-Binding Proteins