The findings suggest that altered Ca2+ current, but not altered Na(+)-Ca2+ exchange current or altered transient outward current, significantly prolongs action potential duration in diabetic rat ventricular muscles.
To evaluate the effects of weight reduction on the autonomic nervous system in obese patients, we investigated heart rate variability (HRV) based on 24-hr ambulatory electrocardiogram (ECG) recordings before and after weight reduction. To aim for weight reduction, 16 obese patients were treated with the verylow-calorie conventional Japanese diet (VLCD-CJ) therapy combined with behavior therapy. Percent weight reduction was 17.8%:t 1.5% (means:t SEM), but mean blood pressure did not change significantly after VLCD-CJ therapy. The mean normal R-R interval (mNN) of the 24-hr ECG and all other five tlmedomain Indices increased after weight reduction. Spectral analysis revealed that weight reduction increased the high frequency (HF) component, but decreased the ratio of low to high (LF/HF) components. Rate of change In mNN or HF correlated positively with reduction rate of body mass Index, but not that In LF/HF. Analysis of dally fluctuations In each HRV parameter showed that significant Improvement after weight loss occurred mainly during the nocturnal period, but an HF component was Improved throughout the day and night periods. These findings Indicate that functional Impairment of the autonomic nervous system in obese subjects, particularly in the nocturnal period, Is improved by effective weight reduction after VLCD-CJ therapy.
Summary:The relationship between QT interval and serum calcium concentration (s-Ca) was examined in 9 hypedcemic (&a > 11 mg/dl) patients. Thnx QT intervals corrected by Bazett's formula were used for the analysis: the intervals from the beginning of the QRS to the onset (QoTc), the apex (QaTc), and the end of T wave (QeTc). The measurements of s-Ca and other electrolytes were made on the blood sample taken on the same day of the electrocardiogram (ECG) recordings. The n o d range of s-Ca and three QTc intervals was determined in 50 outpatients with no cardiac disease. Three QT intervals in the hypedcemic patients were significantly shortened with a diminution in the s-Ca. The QTc intervals showed significant negative correlation with s-Ca. Sensitivity of QoTc, QaTc, and QeTc in predicting high s-Ca was 83 %, 57 %, and 39%, respectively, and specificity was loo%, loo%, and 89%. The PQ interval tended to be prolonged in the case of hypercalcemia, but the change was statistically insignificant. These observations suggest that QT intervals can serve as an indicator of high s-Ca and that the QoTc seems to be a good indicator of the three QTc's.
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