| Abstract: | In a recent study by Anderson and Marks [1982], indirect evidence was presented for the existence of “150-fold muscarinic receptor excess” in the rabbit urinary bladder. This conclusion was based on the quantitative comparison of the ability of carbamylcholine to both directly contract bladder strips and to inhibit (quinuclidinyl benzilate) binding. In order to investigate the presence of “spare receptors” in the bladder directly, we have determined the effect of benzilylcholine mustard (a noncompetitive cholinergic inhibitor) on both bethanechol stimulation of muscle-strip contraction and on [3H]QNB binding (muscarinic receptor density). The results of these studies indicate that there is no significant “muscarinic receptor excess” in the rabbit urinary bladder. |
