Role of prostaglandins in the cardiovascular effects of bradykinin and angiotensin-converting enzyme inhibitors.
The cardiovascular effects of bradykinin require additional vasoactive mediators for a fully balanced response. This includes arachidonic acid (eicosatetraenoic acid) and its metabolites, the eicosanoids (prostaglandins, leukotrienes, thromboxanes, and others). Eicosanoid generation by bradykinin is started by binding of the peptide to specific B2 receptors at the plasma membrane. This initiates G-protein coupled stimulation of phospholipase C, IP3-induced increases in cytosolic Ca2+, and stimulation of protein kinase C. Arachidonic acid is liberated from membrane phospholipids primarily via Ca(2+)-induced stimulation of phospholipase A2 and converted into tissue-specific eicosanoids by enzymes in the vicinity. In vascular tissue, most of the available arachidonic acid is converted into vasodilator prostaglandins, i.e., prostacyclin (PGI2) and prostaglandin E2 (PGE2). These prostaglandins are involved in vasodilator actions of the kinins. There is also some evidence for generation of vasoconstrictor eicosanoids, such as thromboxane A2, under certain conditions. The biological significance of kinin-related prostaglandin formation becomes apparent after inhibition of kinin breakdown by ACE inhibitors. These compounds prevent generation of vasoconstrictor angiotensin II and stimulate endothelial eicosanoid formation via local kinin accumulation. There is evidence suggesting that kinin-induced prostaglandin generation contributes to anti-ischemic, inotropic, and blood pressure-lowering effects of the compounds. This also includes inhibition of polymorphonuclear leukocyte (PMN) accumulation in injured myocardial tissue, which is antagonized by PGI2-related pathways, stimulated by ACE inhibition and/or bradykinin.
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology*; D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002319:Cardiovascular System / Q000187:drug effects*; D006333:Heart Failure / Q000503:physiopathology; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D017202:Myocardial Ischemia / Q000503:physiopathology; D011453:Prostaglandins / Q000378:metabolism* / Q000502:physiology; D018002:Receptors, Bradykinin; D017981:Receptors, Neurotransmitter / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects
D000806:Angiotensin-Converting Enzyme Inhibitors; D011453:Prostaglandins; D018002:Receptors, Bradykinin; D017981:Receptors, Neurotransmitter; D001920:Bradykinin