| Summary: | Background: Ventricular arrhythmia therapy in postmenopausal women using
antiarrhythmic aggravate the risk of arrhythmia, whereas the use of estrogen
replacement therapy is still controversial. Ventricular arrhythmias can prevented
with regular and measurable physical exercise because the effect on heart rate,
action potential duration, repolarization duration, expression of Ca and K ion
channels in cardiac ventricular muscle. Regular and measurable physical exercise
also stimulate extragonadal synthesis of estrogen. Regularly and measurable physical
exercise of the ovariectomized rats needs to be proven prevent ventricular
arrhythmias through electrical activity changes and estrogen synthesis in cardiac
ventricular muscle.
Method: The subjects are Sprague Dawley rats aged 4-5 weeks were ovariectomized
and given regularly and measurable physical exercise using a treadmill (Gamatread
version 2006) for 12 weeks at an intensity equivalent to 60-70% VO2max achieved by
graded exercise. Determination of the QTc interval using a special formula for rats
(Kmecova & Klimas). Expression of Ca and K ion channels, CYP19aromatase, COX2
and estrogen receptor α in cardiac muscle using IHC. To determine the effects of
exercise on Ca and K ion channel using diphenylalkylamin and amiodarone.
Statistical analysis using paired t test, ANOVA and correlation analysis.
Results: The ovariectomized and exercise group that given regular and measurable
physical exercise for 12 weeks lead to QTc interval prolongation (61.58+4.84 to
69.11+2.63 ms) following the RR interval prolongation (125.63+6.23 to
142.19+7,49ms) and a decrease in heart rate (471.69 +24.49 to 414.24 +24.36
x/min) and is correlated (r=0,358) with serum estrogen levels (16.64+5.42 to
18.40+6.3 pg/dL). Ovariectomized with exercise group have a Ca ion channel
expression (85.64 +3.46%) which is higher than group without exercise (67.26
+2.33%), as well as the expression of K ion channels 48.12 +0.55% compared to
39.36 +3.00%, both closely related to QTc interval (r=0,508 and r=0,517).
Ovariectomized with exercise group has CYP19aromatase expression (44.43
+5.56%) which is higher than group without exercise (34.09 +2.62%), as well as
estrogen receptor α 47.80+1.86 % compared to 42.29 +4.56%.
Conclusion: Regular and measurable physical exercise of postovariectomized rats prevent ventricular arrhythmias by causing prolongation of the QTc interval 7,8%
through the increase expressions of Ca and K ion channels. Regular and measurable
physical exercise of postovariectomized rats lead to cardiac muscle cells estrogen
synthesis through the increase of COX2 and CYP19aromatase expression Regular
and measurable physical exercise of postovariectomized rats lead to increase the
expression of estrogen receptor α in the heart muscle.
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