Mechanism of Action
Blood pressure and fluid and electrolyte homeostasis is regulated by the renin-angiotensin-aldosterone-system. Renin, an enzyme released from the kidneys, converts the inactive plasma protein angiotensinogen into angiotensin I (Ang I). Then Ang I is converted to Ang II with angiotensin converting enzyme (ACE), see figure 2. Ang II in plasma then binds to AT-receptors.
ARBs are blocking the last part of the renin-angiotensin pathway and block the pathway more specifically than ACE inhibitors.
The AT1 receptor mediates Ang II to cause increased cardiac contractility, sodium reabsorption and vasoconstriction which all lead to increased blood pressure. By blocking AT1 receptors, ARBs lead to lower blood pressure.
An insurmountable inhibition of the AT1 receptor is achieved when the maximum response of Ang II cannot be restored in the presence of the ARB, no matter how high the concentration of Ang II is. The angiotensin receptor blockers can inhibit the receptor in a competitive surmountable, competitive insurmountable or noncompetitive fashion, depending upon the rate at which they dissociate from the receptor.
Read more about this topic: Discovery And Development Of Angiotensin Receptor Blockers
Famous quotes containing the words mechanism of, mechanism and/or action:
“A mechanism of some kind stands between us and almost every act of our lives.”
—Sarah Patton Boyle, U.S. civil rights activist and author. The Desegregated Heart, part 3, ch. 2 (1962)
“When one of us dies of cancer, loses her mind, or commits suicide, we must not blame her for her inability to survive an ongoing political mechanism bent on the destruction of that human being. Sanity remains defined simply by the ability to cope with insane conditions.”
—Ana Castillo (b. 1953)
“To play is nothing but the imitative substitution of a pleasurable, superfluous and voluntary action for a serious, necessary, imperative and difficult one. At the cradle of play as well as of artistic activity there stood leisure, tedium entailed by increased spiritual mobility, a horror vacui, the need of letting forms no longer imprisoned move freely, of filling empty time with sequences of notes, empty space with sequences of form.”
—Max J. Friedländer (1867–1958)