The Functional Role of Adrenergic Receptors in the Outlet Region of the Urinary Bladder: An in Vitro and in Vivo Study in the Cat

Abstract

Adrencrgic receptor function has been studied in an in vitro preparation of bladder base, bladder neck and proximal urethra, i.e. in the outlet region. In this experimental sysiem changes in resistance to flow and isometric tension in longitudinal musculature could be recorded simultaneously when the preparation was continuously perfused at constant flow rate. It was found that the outflow region had a basal resistance to flow. Alpha-adrcnergic stimulation with metaoxedrine increased while beta-adrenergic stimulation with isoprenaline decreased flow resistance from this basic level. The beta-adrenergic reacticn was far more sensitive than the alpha-adrenergic one and was of longer duration. Similar results were obtained when adrenergic receptor function in the outflow region was studied in vivo in cats: it was then possible to activate and block the adrenergic receptors by the local application of drugs.