RESUMEN
Atrial fibrillation (AF) is the most common supraventricular arrhythmia, and it corresponds highly with exercise intensity. Here, we induced AF in mice using acetylcholine (ACh)-CaCl2 for 7 days and aimed to determine the appropriate exercise intensity (no, low, moderate, high) to protect against AF by running the mice at different intensities for 4 weeks before the AF induction by ACh-CaCl2. We examined the AF-induced atrial remodeling using electrocardiogram, patch-clamp, and immunohistochemistry. After the AF induction, heart rate, % increase of heart rate, and heart weight/body weight ratio were significantly higher in all the four AF groups than in the normal control; highest in the high-ex AF and lowest in the low-ex (lower than the no-ex AF), which indicates that low-ex treated the AF. Consistent with these changes, G protein-gated inwardly rectifying K+ currents, which were induced by ACh, increased in an exercise intensity-dependent manner and were lower in the low-ex AF than the no-ex AF. The peak level of Ca2+ current (at 0 mV) increased also in an exercise intensity-dependent manner and the inactivation time constants were shorter in all AF groups except for the low-ex AF group, in which the time constant was similar to that of the control. Finally, action potential duration was shorter in all the four AF groups than in the normal control; shortest in the high-ex AF and longest in the low-ex AF. Taken together, we conclude that low-intensity exercise protects the heart from AF, whereas high-intensity exercise might exacerbate AF.
RESUMEN
The purpose of this cross-sectional study was to determine the differences in areal bone mineral density (aBMD) based on alcohol consumption behaviors, bone-loading history as assessed by a bone-specific physical activity questionnaire (BPAQ), and the body mass index (BMI). College-aged female students (N = 112) were recruited from the universities in Seoul and Gyeonggi province, South Korea. The aBMD of the lumbar spine and non-dominant side of the proximal femur (total hip, TH; femoral neck, FN; femoral trochanter, FT) were measured using dual energy X-ray absorptiometry (DXA). Alcohol consumption was determined by the frequency and amount of alcohol intake during the past 12 months using a self-reported questionnaire. The X-scan plus II was used to measure height (cm), body mass (kg), fat-free mass (FFM, kg), and % body fat. Drinking two or more times alcohol per week was associated with greater aBMD of the TH (p = 0.04-0.002) and FN (p = 0.043) compared to a lower frequency of alcohol consumption and 2-4 times per month, respectively. Based on the drinking amount per occasion, there were no significant group differences (p > 0.05) in aBMD at any of the sites. The highest group of total BPAQ had greater aBMD of the TH, FN, and FT versus the lowest (p = 0.023-0.009) and mid of total BPAQ groups (p = 0.004-0.009). Additionally, the highest group had greater aBMD of the lumbar spine compared to the mid group (p = 0.001). No significant group differences in aBMD at any of the sites were noted based on the BMI (p > 0.05). Young college-aged women with greater bone-loading physical activity showed greater aBMD at the TH, FN, FT, and lumbar spine, while a moderate alcohol intake was associated with greater aBMD of the TH and FN. These findings have clinical implications for young women who may not participate in high-impact physical activity and are binge drinkers.