logarithm of the concentration of angiotensin II at which the force of blood vessel contraction is half the maximum value (Log EC50) 2013-06-20T14:24:41Z A calculated value for logarithm of the concentration of angiotensin II (AngII), the octapeptide, Asp-Arg-Val-Tyr-Ile-His-Pro-Phe, that is derived from angiotensinogen and acts as a powerful vasopressor and stimulator of aldosterone secretion, at which the energy produced by the active reduction in the diameter of a blood vessel in response to the application of AngII is halfway between the baseline value and the highest achievable value of such AngII-induced contractile energy. The logarithm of the concentration is the exponent indicating the power to which 10 must be raised to obtain that concentration value. Ang2 Log half maximal effective concentration AngII Log half maximal effective concentration JSmith angiotensin 2 Log half maximal effective concentration angiotensin II Log half maximal effective concentration (EC50) angiotensin II response/sensitivity measurement logarithm of the concentration of vasoconstrictor at which the force of blood vessel contraction is half the maximum value (Log EC50)