Central mechanisms in DOC-salt hypertensive rats

Area of Science:

• Cardiovascular Physiology
• Neuroendocrinology
• Renal Physiology

Background:

• Deoxycorticosterone (DOC) and salt administration in rats induces sustained hypertension.
• Central nervous system mechanisms are implicated in the maintenance of this hypertension.
• The role of central angiotensin II (AII) signaling in DOC-salt hypertension requires further elucidation.

Purpose of the Study:

• To investigate the central effects of angiotensin II (AII) on systemic arterial blood pressure and arginine vasopressin (AVP) release in DOC-salt hypertensive rats.
• To determine the contribution of central sympathetic pathways to DOC-salt induced hypertension.

Main Methods:

• DOC-salt treatment in rats to induce hypertension.
• Central and intravenous administration of AII, AVP, and norepinephrine (NE).
• Measurement of systemic arterial blood pressure, plasma AVP levels, and hindquarter vascular resistance.
• Assessment of baroreflex sensitivity.

Main Results:

• DOC-salt rats exhibited augmented pressor responsiveness to centrally injected AII, but not increased AII-induced AVP release.
• Pressor responses to intravenous AII, AVP, and NE were potentiated in DOC-salt rats.
• Baroreflex bradycardia was attenuated, indicating impaired baroreflex function.
• Central AII pressor potentiation exceeded that explained by peripheral factors.

Conclusions:

• Selective central amplification of sympathetic vasomotor responses to AII may contribute to DOC-salt hypertension.
• Baroreflex dysfunction and peripheral mechanisms do not fully account for the heightened pressor response to central AII.
• Central neural circuits play a significant role in mediating hypertension induced by DOC-salt treatment.