Abstract
[Ca2+]i and the Cl- current were measured in isolated submandibular gland acinar and duct cells to characterize and localize the purinergic receptors expressed in these cells. In both cell types 2'-3'-benzoylbenzoyl (Bz)-ATP and ATP increased [Ca2+]i mainly by activation of Ca2+ influx. UTP had only minimal effect on [Ca2+]i at concentrations between 0.1 and 1 mM. However, a whole cell current recording showed that all nucleotides effectively activated Cl- currents. Inhibition of signal transduction through G proteins by guanyl-5'-beta-thiophosphate revealed that the effect of ATP on Cl- current was mediated in part by activation of a G protein-coupled and in part by a G protein-independent receptor. BzATP activated exclusively the G protein-independent portion, whereas UTP activated only the G protein-dependent portion of the Cl- current. Measurement of [Ca2+]i in the microperfused duct showed that ATP stimulated a [Ca2+]i increase when applied to the luminal or the basolateral sides. BzATP increased [Ca2+]i only when applied to the luminal side, whereas UTP at 100 microM increased -Ca2+-i only when applied to the basolateral side. The combined results suggest that duct and possibly acinar cells express P2z receptors in the luminal and P2u receptors in the basolateral membrane.
Highlights
In the intact salivary gland secretion is regulated by several agonists, which include cholinergic, ␣-adrenergic, and -adrenergic agonists (6 – 8)
Because of our recent findings of CFTR expression in SMG duct and acinar cells [28] and the expression of P2 receptors in SMG cells [15, 17,18,19,20,21,22], in the present work we studied the regulation of ClϪ channel activity by P2 receptors in SMG duct and acinar cells
The action of the P2u receptors required the activation of G proteins, whereas that of the P2z receptors was independent of G proteins
Summary
In the intact salivary gland secretion is regulated by several agonists, which include cholinergic, ␣-adrenergic, and -adrenergic agonists (6 – 8). The agonists act on both acinar and duct cells but modulate different activities in the two cell types. Because of our recent findings of CFTR expression in SMG duct and acinar cells [28] and the expression of P2 receptors in SMG cells [15, 17,18,19,20,21,22], in the present work we studied the regulation of ClϪ channel activity by P2 receptors in SMG duct and acinar cells. Measurements of [Ca2ϩ]i and ClϪ current were used to show that SMG acinar and duct cells express at least two types of P2 receptors, a P2z and a P2u receptor. In a companion study [29] we show that the two P2 receptors activate different ClϪ channels that reside in the same membrane as the respective receptor
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
