potassium chloride response/sensitivity measurement logarithm of the concentration of potassium chloride at which the force of blood vessel contraction is half the maximum value (Log EC50) 2014-06-09T18:28:02Z A calculated value for logarithm of the concentration of potassium chloride (KCl) at which the energy produced by the active reduction in the diameter of a blood vessel in response to the application of KCl is halfway between the baseline value and the highest achievable value of such KCl-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. CHEBI:32588 CMO:0002463 JSmith KCl Log half maximal effective concentration (Log EC50) clinical_measurement_ontology potassium chloride Log half maximal effective concentration (Log EC50) logarithm of the concentration of vasoconstrictor at which the force of blood vessel contraction is half the maximum value (Log EC50)