COMPARISON OF THE BINDING OF NICOTINIC AGONISTS TO RECEPTORS FROM HUMAN AND RAT CEREBRAL-CORTEX AND FROM CHICK BRAIN (ALPHA(4)BETA(2)) TRANSFECTED INTO MOUSE FIBROBLASTS WITH ION-CHANNEL ACTIVITY

(-)-Nicotine, cytisine and carbachol evoked Rb-86 efflux from mouse fibroblasts stably transfected with alpha(4) beta(2) chick brain nicotinic subunits. This response to (-)-nicotine was inhibited by mecamylamine and dihydro-beta-erythroidine and was mirrored by a rise in intracellular Ca2+ measured by microspectrofluorimetry. Lobeline and isoarecolone methiodide evoked no significant Rb-86 from cells and unlike the above agonists displayed significantly different IC50 values for the displacement of [H-3]nicotine from mammalian (rat and human cerebral cortex) and transfected fibroblast membranes.