血管紧张素II

Most of the known actions of Angiotensin II (Ang II) are mediated by AT ₁ receptors, the AT ₂ receptor contributes to the regulation of blood pressure and renal function. Angiotensin II raises blood pressure (BP) by a number of actions, the most important ones being vasoconstriction, sympathetic nervous stimulation, increased aldosterone biosynthesis and renal actions. Other Angiotensin II actions include induction of growth, cell migration, and mitosis of vascular smooth muscle cells, increased synthesis of collagen type I and III in fibroblasts, leading to thickening of the vascular wall and myocardium, and fibrosis. These actions are mediated by type 1 Ang II receptors (AT ₁ ). At the cellular level, responsiveness to Angiotensin II is conferred by the expression of the two classes of angiotensin receptors (AT ₁ and AT ₂ ). The effects of Angiotensin II to increase blood pressure are mediated by AT1 receptors.

To distinguish the AT ₁ receptor population that is critical for the pathogenesis of hypertension, osmotic minipumps are implanted s.c. into each animal to infuse Angiotensin II (1,000 ng/kg/min) continuously for 4 weeks. Angiotensin II causes hypertension by activating AT ₁ receptors in the kidney promoting sodium reabsorption.