ESTIMATION OF ANTAGONIST-K(B) FROM INHIBITION CURVES IN FUNCTIONAL EXPERIMENTS - ALTERNATIVES TO THE CHENG-PRUSOFF EQUATION

Recent Principles articles have considered procedures for the function al estimation of an antagonist's dissociation constant from the result s of an antagonist inhibition curve in the presence of a fixed concent ration of agonist. Leff and Dougall (TiPS 14, 110-112) have derived an equation, analogous to the (generally invalid) Cheng-Prusoff equation , which requires that the agonist concentration-effect curves have the form of a logistic function. In the final article of the series, Seba stian Lazareno and Nigel Birdsall consider this equation in the contex t of two related methods for analysing functional inhibition curves - a null method that makes no assumptions about the shapes of curves, an d a curve-fitting method that provides an estimate of the antagonist S child slope.