concentration of acetylcholine at which the reduction in force during dilation of a blood vessel is half the maximum value (EC50) logarithm of the concentration of acetylcholine at which the reduction in force during dilation of a blood vessel is half the maximum value (Log EC50) CHEBI:15355 clinical_measurement_ontology acetylcholine Log half maximal effective concentration (Log EC50) CMO:0000725 2012-03-14T04:24:16Z A calculated value for logarithm of the concentration of acetylcholine (ACh), the ester of acetic acid and choline with chemical formula CH3C=OO(CH2)2-N(+)-(CH3)3 and IUPAC name 2-acetoxy-N,N,N-trimethylethanaminium, which acts as a neurotransmitter, at which the dilation of a blood vessel in response to the application of ACh is half maximal. The logarithm of the concentration is the exponent indicating the power to which 10 must be raised to obtain that concentration value. VT:0005594 jsmith