Search

The effect of four different blood pressure reducers (antihypertensives) on blood pressure during everyday life stress and during stress induced in a laboratory was studied. Sixty middle-aged men with mild to moderate high blood pressure (hypertension), never previously treated, were treated with low dose clonidine, oxprenolol, nitrendipine, or enalapril. All four groups were similar in age, weight, degree of obesity and blood pressure. After six months of therapy, diastolic (i.e., while the heart is at rest, between beats) blood pressure was the same in all four groups. Systolic blood pressure (during the pumping phase) was lower in patients treated with clonidine or oxprenolol than those treated with enalapril. Blood pressure under stress was lowest in patients treated with oxprenolol and nitrendipine together. Oxprenolol was not as effective as nitrendipine or enalapril during mental stress tests.

Obese persons suffer from an increased mortality risk supposedly due to cardiovascular disorders related to either continuously lowered parasympathetic or altered sympathetic activation. Our cross-sectional correlation study establishes the relationship between obesity and autonomic regulation as well as salivary cortisol levels. Three patient cohorts were sampled, covering ranges of body mass index (BMI) of 27-32 (n=17), 33-39 (n=13) and above 40 kg/m(2)(n=12), and stratified for age, sex and menopausal status. Autonomic cardiovascular regulation was assessed by use of heart rate variability and continuous blood pressure recordings. Spectral analytical calculation (discrete Fourier transformation) yields indices of sympathetic and parasympathetic activation and baroreflex sensitivity. Morning salivary cortisol was concurrently collected. Contrary to expectation, BMI and waist/hip ratio (WHR) were inversely correlated with sympathetic activity. This was true for resting conditions (r=-0.48, P<0.001; r=-0.33, P<0.05 for BMI and WHR respectively) and for mental challenge (r=-0.42, P<0.01 for BMI). Resting baroreflex sensitivity was strongly related to the degree of obesity at rest (BMI: r=-0.35, P<0.05) and for mental challenge (r=-0.53, P<0.001). Salivary cortisol correlated significantly with waist circumference (r=-0.34, P=0.05). With increasing weight, no overstimulation was found but a depression in sympathetic and parasympathetic activity together with a significant reduction in baroreflex functioning and in salivary cortisol levels.

The effects of the calcium antagonist isradipine and the ß-blocker metoprolol, which are based on different antihypertensive therapeutic principles, were evaluated in 52 men with mild-to-moderate hypertension in a 6-week, double-blind, randomized study. Mental stress-testing was performed before and after active treatment. With isradipine (n= 26), the stress-induced responses of cardiac output and total peripheral resistance were not significantly changed, but the blood pressure (BP) response, specifically the diastolic response, was decreased. With metoprolol (n= 26), there was a decreased response of cardiac output and an increased response of total peripheral resistance, and the BP response was even greater than it had been before treatment. Thus, these results indicate that ß-blockade is effective in reducing cardiac responsiveness but, because of vascular counterregulatory mechanisms, BP responsiveness is not decreased. In contrast, calcium antagonism preserves the physiological hemodynamic profile while reducing BP responsiveness to stress.