Characterization of the α1 adrenoceptor subtype (α1 AR) and its signaling pathway for activation of ERK 1/2 in submandibular gland acinar cells

We recently reported that submandibular gland acinar cells express both the α1A- and α1B-AR subtypes; however, the function of these subtypes in acinar cells is unknown. Extracellular signal-regulated kinases (ERK 1/2) are important signaling molecules in the mitogen-activated protein kinase family. Preliminary studies indicated the neurotransmitter norepinephrine stimulates ERK 1/2 in acinar cells; however, nothing is known about the α1-AR subtype and its signal transduction pathway activating ERK 1/2. Thus, we used Western blot analysis to characterize the α1-AR subtype and its signaling pathway for activating ERK 1/2 phosphorylation in submandibular gland acinar cells. Phenylephrine (10 – 100 μM) stimulated a 4-fold increase in phosphorylated ERK 1/2 over basal that was blocked by 100 nM prazosin but not by 20 nM 5-methylurapidil. In addition, chloroethylclonidine completely inhibited …