Medical Pharmacology Chapter 24: Vasoactive Peptides
Sites of Action: Angiotensin II
Vascular smooth muscle
Arterial blood pressure regulation
Fluid and electrolyte balance regulation
Blood Pressure/Cardiovascular Effects: Angiotensin II
Very potent vasopressor (40 times more potent than norepinephrine).
Following IV administration, rapid pressor effect.
Vasopressor response: Mechanisms of Action
Direct arteriolar smooth muscle contraction.
Minimal reflex bradycardia (angiotensin II CNS action resets baroreceptor reflex system, making it less sensitive).
Stimulates autonomic ganglia
Promoting release of epinephrine and norepinephrine.
Enhances adrenergic nerve terminal neurotransmission.
Iincreases norepinephrine release; reduces norepinephrine re-uptake.
Acts on zona glomerulosa, increasing aldosterone synthesis.
At higher doses angiotensin II increases glucocorticoid synthesis.
Enhanced sodium reabsorption at proximal tubule
Inhibition of renin secretion
Central blood-pressure effects
Stimulates drinking (dipsogenic effect)
Stimulates vasopressin and ACTH secretion
Vascular and cardiac muscle cell mitogen
May cause myocardial hypertrophy
Angiotensin converting enzyme inhibitors may reduce or prevent morphological changes following myocardial infarction (remodeling), which may lead to cardiac failure (CHF).
Reid, I.A., Vasoactive Peptides, in Basic and Clinical Pharmacology, (Katzung, B. G., ed) Appleton-Lange, 1998, pp 287-303.