SUBCELLULAR-DISTRIBUTION AND PHARMACOLOGICAL IDENTIFICATION OF M1 RECEPTORS IN THE SUBMUCOSAL NASAL GLAND ACINAR-CELLS OF GUINEA-PIGS

A muscarinic receptor in the submucosal nasal gland acinar cells contr ols electrolyte and fluid secretion. We investigated the pharmacologic al identification and the subcellular distribution of M1 receptor usin g a selective antagonist, pirenzepine (PZ). Intracellular Ca2+ concent ration ([Ca2+](i)) in the isolated acinar cells was measured by a fura -2 method. Addition of PZ inhibited the increase of the [Ca2+](i) indu ced by acetylcholine in a dose-dependent manner, indicating the presen ce of the M1 receptor. Both fixed section of the nasal septal mucosa a nd living isolated acinar cells were selectively stained by fluorescen ce-labeled PZ. Furthermore, confocal laser scanning microscopy reveale d that PZ specifically labeled the plasma membrane in the isolated aci nar cells. Thus, M1 receptor was proven to be located in the plasma me mbrane of the submucosal nasal gland acinar cell.