OBJECTIVETo identify the effect of ethanol and its metabolite acetaldehyde on acetylcholine-sensitive K(+) channel Kir3.1 protein expression, and explore the potential role of this channel and acetaldehyde in arrhythmia caused by acute alcoholic intoxication.

METHODSPrimary atrial cardiomyocytes were isolated from 150 newborn SD rats by typsin and type II collagenase, cultured and troponin I was determined by immunofluorescence. Cell survival in 200-800 mmol/L ethanol or 50-500 µmol/L acetaldehyde treated cells for 24 hours was measured by CCK-8 assay to determine the concentration of ethanol and acetaldehyde for inducing apoptosis in cardiomyocytes. The highest non-apoptotic concentration (200 mmol/L) of ethanol and acetaldehyde (100 µmol/L) was used in the main study. Kir3.1 protein expression was detected by Western blot.

RESULTS(1) Cellular immunofluorescence results showed that cultured cells are cardiomyocytes, and more than 90% of these cells are troponin I positive. (2) CCK-8 assay demonstrated that the survival rate of cardiomyocytes in the groups treated by ethanol over 400 mmol/L for 24 hours or acetaldehyde over 400 µmol/L was significantly lower than that of the control group (P < 0.05), while the survival rate was similar in cardiomyocytes treated by ethanol less than 200 mmol/L or acetaldehyde less than 350 µmol/L for 24 hours and the control group (P > 0.05). (3) Western-bolt assay revealed that ethanol and acetaldehyde treatment for 24 hours upregulated Kir3.1 protein expression in primary atrial cardiomyocytes of newborn SD rats by (44.52 ± 23.07)% and (45.04 ± 22.01)% respectively compared with the control group (all P < 0.01).

CONCLUSIONSAcute ethanol and acetaldehyde treatment could significantly upregulate the protein expression of acetylcholine-sensitive K(+) channel Kir3.1, this might serve as a potential mechanism for arrhythmia caused by acute alcoholic intoxication.