Binding of optically pure (−)‐[³H]nicotine to rat brain membranes

With the recent availability of (--)-[3H]nicotine of high specific activity, binding studies were performed on rat brain membranes in the presence of a variety of nicotine analogues and cholinergic drugs. Both a higher affinity (Kd = 2 X 10(-10) M) and a lower affinity (2 X 10(-9) M) site were observed; the stereoselectivity of both sites being similar. A good correlation was observed between IC50-values and psychotropic potency of a series of N'-alkyl substituted nicotine analogues.