Comparison of Muscarinic Cholinergic and Alpha Adrenergic Receptors in Canine Ileum, Colon, Intestinal Urinary Reservoirs and Bladder

Abstract

The muscarinic cholinergic (MCh) and alpha2 adrenergic receptor densities in canine ileum, colon, ileal and colonic urinary reservoirs and bladder were determined using radioligand receptor binding methods in order to provide a rational basis for pharmacologic management of urinary incontinence following bladder replacement with intestinal segments. Muscarinic cholinergic and alpha2 adrenergic receptor binding sites were studied in these tissues using saturation experiments with 3H-NMS and 3H-rauwolscine, respectively. The mean equilibrium dissociation constants for 3H-NMS binding (0.13 to 0.17nM) in these tissues were similar (p > 0.05) indicating homogeneity of muscarinic cholinergic binding sites. The mean equilibrium dissociation constants for 3H-rauwolscine binding (1.27 to 1.98nM) in these tissues were also similar (p > 0.05). A substantial density of MCh (1.06 to 1.22fmol/mg. wet wt.) and alpha2 adrenergic (0.47 to 1.11fmol/mg. wet wt.) binding sites was identified in the intestinal tissues assayed. The density of ileal and colonic MCh and alpha2 adrenergic binding sites was not altered following construction of urinary intestinal reservoirs. The presence of a substantial density of MCh and alpha2 adrenergic binding sites in the intestinal tissues suggests that MCh and alpha2 adrenergic analogs may be utilized for the management of urinary incontinence following bladder replacement with intestinal urinary reservoirs.