calculated blood vessel dilation force reduction measurement logarithm of the concentration of sodium nitroprusside at which the reduction in force during dilation of a blood vessel is half the maximum value (Log EC50) 2012-03-14T04:25:16Z A calculated value for logarithm of the concentration of sodium nitroprusside (SNP), the red-coloured inorganic salt with the formula Na2[Fe(CN)5NO]-2H2O used as a potent vasodilator, at which the energy exerted during the active expansion in the diameter of a blood vessel in response to the application of SNP is halfway between the highest value, that is the force at greatest constriction (often measured in a pre-constricted blood vessel), and the lowest achievable value of such contractile energy during SNP-induced relaxation of the vessel wall (i.e. the maximum effect of SNP which is the minimum contractile energy). JSmith sodium nitroprusside Log half maximal effective concentration (Log EC50) sodium nitroprusside response/sensitivity measurement