Is vasopressin an important hypertensive hormone?

Area of Science:

• Cardiovascular Physiology
• Endocrinology
• Renal Physiology

Background:

• Arginine vasopressin (AVP) plays a role in blood pressure regulation.
• Understanding AVP's hypertensive potential is crucial for managing cardiovascular conditions.
• Existing research on AVP's chronic effects on blood pressure is limited.

Purpose of the Study:

• To quantitatively assess the hypertensive activity of chronic arginine vasopressin (AVP) infusion.
• To investigate AVP's effects in both normotensive and pre-hypertensive canine models.
• To compare AVP's impact on mean arterial pressure (MAP) under different hormonal conditions.

Main Methods:

• Chronic infusion of AVP at 140 and 560 microunits/kg/min in normotensive dogs.
• Chronic infusion of AVP in dogs with angiotensin II (AII) or aldosterone-induced hypertension.
• Continuous monitoring of mean arterial pressure (MAP) and daily fluid/electrolyte balance.
• Controlled daily saline infusion to all dogs.

Main Results:

• In normotensive dogs, AVP initially caused water retention and increased MAP, followed by diuresis and a decrease in MAP.
• In AII or aldosterone-hypertensive dogs, AVP infusion resulted in attenuated natriuresis and minimal or transient increases in MAP.
• Cessation of AVP in hypertensive models led to a transient drop in MAP, followed by fluid retention and return to baseline hypertension.

Conclusions:

• Chronic high plasma AVP levels exhibit weak long-term hypertensive effects, particularly in established hypertension models.
• AVP has pronounced acute effects on MAP but minimal sustained hypertensive impact.
• The interplay between AVP and other pressor systems (AII, aldosterone) significantly modulates AVP's hypertensive role.