Showing papers by "Tomi Laitinen published in 2002"

Gender influence on vasoactive hormones at rest and during a 70° head-up tilt in healthy humans

Abstract: To evaluate the influence of age and gender on the neuroendocrine control of blood pressure in normal subjects, a 13-min 70° head-up tilt (HUT) was applied after 3 h of recumbency to 109 healthy me

Baroreflex sensitivity in essential and secondary hypertension.

Abstract: Baroreceptor reflex regulation has been shown to reset towards a higher blood pressure level and to operate with reduced sensitivity in hypertension. Whether this is secondary to elevated blood pressure or whether it plays a role in the development of hypertension is not known. In addition, only limited data exist on baroreflex sensitivity (BRS) in patients with long-lasting medically treated essential hypertension and in patients who have blood pressure elevation with similar severity, but of different etiology. The purpose of this study was to examine BRS in patients with different severity and forms of chronic, medically treated hypertension. Patients with renovascular hypertension (RVHT, n = 14), severe essential hypertension (SEHT, n = 36) and mild essential hypertension (MEHT, n = 29) as well as healthy age- and sex-matched control subjects were studied. BRS was measured with the phenylephrine method. BRS in the RVHT (3.7 ± 0.6 ms/mmHg) and SEHT (7.6 ± 0.8 ms/mmHg) groups did not differ from each other after age, gender and left ventricular mass index were taken into consideration. On the contrary, BRS in the RVHT (p = 0.008) and SEHT (p = 0.016) groups were lower than in the MEHT (8.5 ± 1.2 ms/mmHg) group. BRS was also significantly reduced in the RVHT (P = 0.004) and SEHT groups (P = 0.006) when compared to the healthy age- and sex-matched controls. BRS in the MEHT group did not differ from the control subjects. In conclusion, BRS was equally impaired in patients with renovascular and severe essential hypertension, which was similar in severity but different in etiology. BRS in patients with long-lasting medically treated mild essential hypertension did not differ from the healthy subjects. Our study suggests that baroreflex dysfunction in hypertensive patients is related to the clinical severity of hypertension, rather than its etiology.

Effects of endurance training on heart rate and blood pressure variability.

Abstract: Purpose: To study the influences of a 1-year controlled, randomized endurance exercise training period on heart rate (HR) and blood pressure variability in a representative sample of Finnish men in their late middle age. Methods and results: Subjects were 140 sedentary men aged 53–63 years. The men were randomized into two identical groups: an intervention (EX) and a reference (CO) group. One hundred and twelve of them remained in the final analysis (EX: n=59, CO: n=53). EX trained for 30–60 min three to five times a week with the intensity of 40–60% of maximal oxygen consumption. In EX, 1 year of regular exercise training increased oxygen consumption at respiratory compensation threshold by 11% (P ≤ 0·001) in a maximal cardiorespiratory test. Total power and very low frequency power of R–R interval variability (ms2) tended to increase in the EX group by 26 and 42% and to decrease in the CO group by 13 and 10% (interaction P<0·05 and P<0·01), respectively. There were no significant changes in blood pressure variability. Conclusion: Regular low- to moderate-intensity exercise training could retard the decli-ning tendency in cardiac autonomic nervous function in older men during 1 year.

Does postmenopausal hormone replacement therapy affect cardiac autonomic regulation in osteoporotic women

Abstract: OBJECTIVE Postmenopausal hormone replacement therapy (HRT) has been associated with reduced risk of cardiovascular disease; however, the mechanisms remain obscure, and it is not known whether this applies to regimens containing both estrogen and progestin. One possibility is that estrogen would act via enhancement of cardiac autonomic regulation. DESIGN In this prospective, controlled study of 6-months duration, 22 osteoporotic, postmenopausal women in the intervention group were treated with combined estradiol hemihydrate corresponding to estradiol 2 mg and norethisterone acetate 1 mg with or without clodronate (HRT group). Nine women in the control group received clodronate only. Indices of heart rate variability (HRV) by power spectral analyses and baroreceptor sensitivity (BRS) by phenylephrine test were measured before and after 3 and 6 months of treatment. RESULTS The total power of HRV remained identical within the groups, although it was higher at 3 and 6-month measurements in the control group than the HRT group. This was mainly due to lower very low frequency and high frequency power in the HRT group. However, no changes in the low frequency/high frequency-ratio of HRV, an index of sympathovagal balance, were observed between and within the groups. Further, during the intervention, no significant changes in BRS (baseline and 6 months: 5.0 +/- 2.1 and 5.1 +/- 2.5 ms/mmHg) within the HRT group was observed. CONCLUSIONS The impact of estrogen and progesterone on cardiac autonomic regulation seems to be quite modest. Therefore, cardiac morbidity and mortality are probably not mediated by their effects on cardiac autonomic regulation. However, the effects of estrogen alone or more selective estrogen receptor modulators need yet to be clarified in future studies.

Taichiquan acutely increases heart rate variability.

Abstract: A group of 15 elderly men and 14 young male students of physical education made twice a series of Taichiquan (TCQ) practices. Their electrocardiograms were recorded on tape-recorder and heart rates and heart rate variability (HRV) were calculated from digitized data. Here we report the results of recordings in supine positions before and after the first and second series of TCQ. Intervals between heart beats (RRIs) and their standard deviation (SDNN) increased in older men from recordings before the exercise to postexercise. In young subjects the SDNN and total variance (TV) of RRIs increased. HRV increases immediately after TCQ-exercise in young and old male healthy subjects. Whether these practices have permanent effects and effects in patients need controlled and prospective studies.