Characterization of muscarinic acetylcholine receptors in the avian salt gland.

摘要: Electrolyte and fluid secretion by the avian salt gland is regulated activation of muscarinic acetylcholine receptors (R). In this study, these were characterized quantitated in homogenates from domestic ducks adapted to conditions low (freshwater, FW) high (saltwater, SW) stress using cholinergic antagonist [3H]-quinuclidinyl benzilate (QNB). Specific binding both FW- SW-adapted glands reveals a single population affinity sites (KdFW = 40.1 +/- 3.0 pM; KdSW 35.1 2.1 pM). Binding saturable; RLmaxFW 1.73 0.10 fmol/micrograms DNA; RLmaxSW 4.16 0.31 DNA (where L [3H]QNB RL complex). Calculated average cellular receptor populations 5,800 sites/cell FW-adapted 14,100 demonstrate that upward regulation secretory epithelium follows chronic stress. The exhibits typical pharmacological specificities for antagonists (QNB, atropine, scopolamine) agonists (oxotremorine, methacholine, carbachol). addition, loop diuretic furosemide, which interferes with ion transport processes gland, competitively inhibits binding. Preliminary studies furosemide effects on rat exorbital lacrimal membranes showed similar inhibition, although had no effect brain or atrial receptors.