Hypotensive and sympathoinhibitory responses to selective central AT2 receptor stimulation in spontaneously hypertensive rats

The type 2 angiotensin (AT2) receptor has been suggested to counterbalance the type 1 angiotensin (AT1) receptor in the central regulation of blood pressure and sympathetic tone. We here investigated the blood pressure responses to stimulation of central AT2 receptors by the selective agonist Compound 21 in conscious SHR and normotensive WKY rats. We also assessed the impact on norepinephrine plasma levels, autonomic function, spontaneous baroreflex sensitivity, and the possible involvement of the nitric oxide-pathway and the AT1 receptor. Chronic intracerebroventricular Compound 21 infusion lowered blood pressure and norepinephrine plasma levels in both rat strains. The nighttime hypotensive effect was greater in SHR compared to WKY. Compound 21 improved spontaneous baroreflex sensitivity more in SHR than in WKY. These effects were abolished by co-administration of AT2 receptor antagonist PD123319 or nitric oxide-synthase inhibitor L-NAME. Central AT1 receptor blockade did not enhance the hypotensive response to Compound 21. Chronic selective stimulation of central AT2 receptors lowers blood pressure through sympatho-inhibition, and improves spontaneous baroreflex sensitivity more in SHR than in WKY. These responses appear to require a functioning central nitric oxide-pathway, but are not modified by central AT1 receptor blockade. Collectively, the data demonstrate specific beneficial effects of stimulation of central AT2 receptors in hypertension associated with increase...
Source: Clinical Science - Category: Biomedical Science Authors: Source Type: research

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AbstractPurpose of ReviewThe present paper will review the results of experimental and clinical studies aimed at defining the functional behavior of the central and peripheral nervous system in adrenal pheochromocytoma.Recent FindingsThe contribution of sympathetic neural influences to the development of high blood pressure values in pheochromocytoma is complex. Studies performed in experimental animal models have shown that hypertension and the concomitant high circulating levels of catecholamines can lead to inhibition of central sympathetic neural outflow by reflex mechanisms and direct stimulation of central adrenergic...
Source: Current Hypertension Reports - Category: Primary Care Source Type: research
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Source: Current Hypertension Reports - Category: Primary Care Source Type: research
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Source: Clinical and Experimental Hypertension - Category: Cardiology Authors: Tags: Clin Exp Hypertens Source Type: research
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Source: American Journal of Hypertension - Category: Cardiology Authors: Tags: Am J Hypertens Source Type: research
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Source: Cardiology Journal - Category: Cardiology Authors: Tags: Cardiol J Source Type: research
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Source: Journal of the Association of Physicians of India - Category: General Medicine Tags: J Assoc Physicians India Source Type: research
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Source: European Journal of Pharmacology - Category: Drugs & Pharmacology Authors: Tags: Eur J Pharmacol Source Type: research
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Source: American Journal of Hypertension - Category: Cardiology Authors: Tags: Am J Hypertens Source Type: research
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Source: Cardiovascular Journal of Africa - Category: Cardiology Authors: Tags: Cardiovasc J Afr Source Type: research
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Source: Clinical Research in Cardiology - Category: Cardiology Source Type: research
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