A difference in sensitivity to alpha adrenergic agonists exhibited by detrusor and bladder neck of rabbit

In cumulative dose response studies, strips from bladder neck of rabbit were significantly more sensitive to stimulation with noradrenaline, phenylephrine, and methoxamine than were strips from detrusor. There was no difference between the two regions in sensitivity to isoprenaline or carbachol. From the known characteristics of these agents, it seemed unlikely that metabolic destruction or uptake could account for the different sensitivities seen. Also, neither normetanephrine nor desmethylimipramine could alter significantly the potency of noradrenaline in either area of the bladder. It seems likely that the difference in sensitivity to alpha adrenoceptor stimulation in the bladder neck and detrusor is due to factors at the receptor level.