Effects of benazepril on stress testing blood pressure in essential hypertension

Brain angiotensin AT1 receptors as specific regulators of cardiovascular reactivity to acute psychoemotional stress

1. Cardiovascular reactivity, an abrupt rise in blood pressure (BP) and heart rate in response to psychoemotional stress, is a risk factor for heart disease. Pharmacological and molecular genetic studies suggest that brain angiotensin (Ang) II and AT(1) receptors are required for the normal expression of sympathetic cardiovascular responses to various psychological stressors. Moreover, overactivity of the brain AngII system may contribute to enhanced cardiovascular reactivity in hypertension. 2. Conversely, brain AT(1) receptors appear to be less important for the regulation of sympathetic cardiovascular responses to a range of stressors involving an immediate physiological threat (physical stressors) in animal models. 3. Apart from threatening events, appetitive stimuli can induce a distinct, central nervous system-mediated rise in BP. However, evidence indicates that brain AT(1) receptors are not essential for the regulation of cardiovascular arousal associated with positively motivated behaviour, such as anticipation and the consumption of palatable food. The role of central AT(1) receptors in regulating cardiovascular activation elicited by other types of appetitive stimuli remains to be determined. 4. Emerging evidence also indicates that brain AT(1) receptors play a limited role in the regulation of cardiovascular responses to non-emotional natural daily activities, sleep and exercise. 5. Collectively, these findings suggest that, with respect to cardiovascular arousal, central AT(1) receptors may be involved primarily in the regulation of the defence response. Therefore, these receptors could be a potential therapeutic target for selective attenuation of BP hyperreactivity to aversive stressors, without altering physiologically important cardiovascular adjustments to normal daily activities, sleep and exercise.

AT1 receptors in the RVLM mediate pressor responses to emotional stress in rabbits

In this study, we examined the role of angiotensin type 1 (AT1) receptors in the rostral ventrolateral medulla (RVLM) in mediating the pressor action of emotional stress in conscious rabbits. Rabbits were chronically instrumented with guide cannulas for bilateral microinjections into the RVLM and an electrode for measuring renal sympathetic nerve activity (RSNA). Airjet stress evoked increases in arterial pressure, heart rate, and RSNA, which reached a maximum (+9+/-1 mm Hg, +20+/-5 beats/min, and +93+/-17%, respectively) in the first 2 minutes of stress exposure. Then RSNA rapidly returned to prestress values, while arterial pressure and heart rate remained close to the maximal level until the conclusion of the 7-minute airjet exposure. Microinjections of the nonselective angiotensin receptor antagonist sarile (0.5 nmol, n=8) or AT1 receptor antagonists losartan (2 nmol, n=6) or candesartan (0.2 nmol, n=6) into the RVLM did not alter resting cardiovascular parameters. By contrast, the antagonists attenuated the sustained phase (4 to 7 minutes) of the pressor stress response by 55% to 89%. However, only sarile decreased the onset of this response. The antagonists affected neither the stress-induced tachycardia nor the pressor response to glutamate microinjections. Microinfusion of angiotensin II (4 pmol/min, n=8) into the RVLM did not change the pressor response to airjet stress but attenuated tachycardic response by 47%. Microinjections of vehicle did not alter the cardiovascular stress response. Sarile, losartan, and angiotensin II did not affect the sympathoexcitatory response to baroreceptor unloading. These results suggest that AT1 receptors in the RVLM are important in mediating the pressor effects of emotional stress in conscious rabbits.

Effects of fosinopril treatment on blood pressure during physical and mental stress test in essential hypertension

In this study the effects of once daily administration of 10 mg fosinopril on blood pressure response to mental and physical stress were evaluated in mild to moderate essential hypertension. A total of 25 patients (14 women, 9 men) with mild to moderate essential hypertension were enrolled in this study. Before the treatment and after 10 mg/day fosinopril treatment for 2 months, systolic and diastolic blood pressure and heart rate were recorded at rest and while performing a mental arithmetic test. In addition, exercise stress testing with Bruce protocol were performed before and after the treatment and systolic and diastolic blood pressure and heart rate were recorded at rest and during peak exercise. Statistical analysis were done by using the paired t-test. During the mental arithmetic test, systolic and diastolic blood pressure were significantly reduced (p < 0.005 and p < 0.001, respectively) after 2 months fosinopril treatment. Systolic and diastolic blood pressure were also significantly reduced during the exercise stress test (p < 0.005 and p < 0.05) after the treatment. Heart rate did not change during either the mental arithmetic or the exercise test. As a result, once daily 10 mg fosinopril may be effective in reducing blood pressure, not only at rest, but also during stressful situations.