There is much evidence regarding autonomic dysfunction in obesity in adults, but information on autonomic status in obese children is scant. In the present study autonomic function tests were conducted in 30 normal and 30 obese children aged between 5 and 10 years. We performed tests for parasympathetic function (resting heart rate, S:L ratio (standing to lying ratio), 30:15 ratio and Valsalva ratio) and tests to assess sympathetic function (blood pressure response to hand grip test and cold pressor response). The children were classified as normal and obese on the basis of BMI (body mass index). Children with BMI between 20 to 24.9 were classified as normal and those with BMI > 30 as obese. The mean values of hand grip test and cold pressor response were significantly lower in the study group compared with controls (P < 0.05), however the Valsalva ratio was higher in the obese compared with normal children. Hence, our study showed compromised autonomic nervous system functions in the obese group compared with controls

We compared the role of vegetarian and non-vegetarian diet on vascular reactivity in response to mental stress. Vegetarian under-graduate medical students (n = 100) were compared with non-vegetarian students (n = 100) both at rest and after examination stress. The measured parameters included systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), mean blood pressure (MBP) and heart rate (HR). Both groups showed significant vascular re- activity to mental stress but the non-vegetarians had higher BP and HR values both at rest and after exposure to stress. Under resting conditions, the SBP, DBP, PP, MBP (mmHg), HR (bpm) in the vegetarians were 127.7 ± 6.4, 77.8 ± 4.4, 49.9 ± 5.9, 94.5 ± 4.3, 77.1 ± 2.1 and in the non-vegetarian group were 133.7 ± 7.7, 86.0 ± 5, 47.7 ± 6.8, 101.9 ± 5.1, 82.3 ± 2.7, respectively. All the values except PP in the non-vegetarian group were significantly higher when compared with the vegetarian group (p < 0.05). After exposure to stress, the SBP, DBP, PP, MBP (mmHg), HR in the vegetarian group were 132.2 ± 6.5, 80.3 ± 4.6, 51.8 ± 6.8, 97.6 ± 4.2, 82.3 ± 2.7 and in the non-vegetarian group were 141.9 ± 7.9, 91.8 ± 6.7, 50.0 ± 7.5, 108.5 ± 6.2, 86.4 ± 3.0, respectively. All the values except PP in the non-vegetarian group were signifi- cantly higher when compared with the vegetarians (p < 0.05). The post-stress values were significantly greater than those taken at rest (p<0.05). This study showed better coping to mental stress in vegetarians and suggests a greater risk to develop future hypertension in non-vegetarians according to the reactivity hypothesis. Prospective follow-up studies are needed to test this hypothesis.

Women have a slower cardiac repolarization than men, which manifests as longer heart rate corrected QT in- terval (QTc) on the ECG. This study was undertaken to identify cyclical variations of QTc and to detect whether it can further be modulated by handgrip exercise. ECG changes were recorded before and after handgrip exercise during different phases of menstrual cycle in 30 healthy women (25-40 yrs) with a regular menstrual cycle. The different menstrual cycle phases were assigned on the basis of dates and confirmed by plasma levels of estrogen and progesterone. Daily basal body temperature was recorded to con- firm the ovulatory phase. ECG parameters (in lead II) were recorded before and immediately after release of handgrip. During the menstrual phase, the basal RR interval was 0.765 ± 0.03 sec and after handgrip exercise, it increased to 0.829 ± 0.02 sec (p<0.05). The QTc interval was maximal in the menstrual phase (0.44 ± 0.007). There was a significant decrease in QTc interval in the menstrual phase (0.41 ± 0.009 sec, p<0.05) after handgrip exercise. This study confirms the cyclic variation of the QTc interval. The prolonged QTc interval during the menstrual phase is likely to produce arrhythmias if women are exposed to agents which further prolong the refractory period. A fall in the QTc interval was seen after handgrip exercise during the menstrual phase, females may be advised to engage themselves in isometric activities so as to decrease their susceptibility to arrhythmias.

Hypertension (HT) has been known since times immemorial to be one of the major causes of morbidity and mortality. It contributes to atherosclerotic cardiovascular disease, increasing its risk 2-3 times and is also associated with dyslipidemia, insulin resistance, glucose intolerance and obesity (1). The age of onset of hypertension is now earlier than before, making it essential that early detection of people who could be future hypertensives is done. Therefore, cardiovascular reactivity to stress in predicting future hypertension becomes important. In this fast paced age most people are exposed to mental stress which is the most common and prevalent form of stress. Increase in blood pressure (BP) in response to emotional arousal is well known, but support for this hypothesis of reactivity in predicting future hypertension is limited. We are attempting here to put forth a review of the various endeavours done so far to support this hypothesis.