Four Voltage-Gated Potassium Currents in Trigeminal Root Ganglion Neurons

Various voltage-gated K+ currents were recently described in dorsal root ganglion (DRG) neurons. However, the characterization and diversity of voltage-gated K+ currents have not been well studied in trigeminal root ganglion (TRG) neurons, which are similar to the DRG neurons in terms of physiological roles and anatomy. This study was aimed to investigate the characteristics and diversity of voltage-gated K+ currents in acutely isolated TRG neurons of rat using whole cell patch clamp techniques. The first type (type I) had a rapid, transient outward current (I(A)) with the largest current size having a slow inactivation rate and a sustained delayed rectifier outward current (I(K)) that was small in size having a fast inactivation rate. The I(A) currents of this type were mostly blocked by TEA and 4-AP, K channel blockers whereas the I(K) current was inhibited by TEA but not by 4-AP. The second type had a large I(A) current with a slow inactivation rate and a medium size-sustained delayed IK current with a slow inactivation rate. In this second type (type II), the sensitivities of the I(A) or I(K) current by TEA and 4-AP were similar to those of the type I. The third type (type III) had a medium sized I(A) current with a fast inactivation rate and a large sustained I(K) current with the slow inactivation rate. In type III current, TEA decreased both I(A) and I(K) but 4-AP only blocked I(A) current. The fourth type (type IV) had a smallest I(A) with a fast inactivation rate and a large IK current with a slow inactivation rate. TEA or 4-AP similarly decreased the I(A) but the I(K) was only blocked by 4-AP. These findings suggest that at least four different voltage-gated K+ currents in biophysical and pharmacological properties exist in the TRG neurons of rats.

Immunohistochemical study of nitric oxide synthase in salivary glands / 대한해부학회지

Endogenous nitric oxide (NO) has been known to regulate the salivary secretion and glandular blood flow. However, nitric oxide synthase (NOS) responsible for NO synthesis has not been well studied in salivary glands. The present study was aimed to investigate the distribution of nitric oxide synthase isoforms (endothelial, neuronal, and inducible NOS). Immunohistochemistry, using monoclonal mouse anti-endothelial NOS, anti-neuronal NOS, and anti-inducible NOS, was performed in 3 major salivary glands of the rat. Endothelial NOS (eNOS)-positive immunoreactivity was observed in arterial endothelium, striated duct, granular convoluted duct of the submandibular gland, intercalated duct, and mucous acinar cells of the sublingual gland. eNOS-positive immunoreactivity was most prominent in the arterial endothelial layer and that of the striated and granular convoluted duct was well concentrated in columnar epithelial layer. However, eNOS-positive immunoreactivity of the intercalated duct and mucous acinus was weak. Neural NOS (nNOS)-positive immunoreactivity was seen in submandibular ganglion, autonomic postganglionic fiber, striated duct, granular convoluted duct, and intercalated duct. nNOS-positive immunoreactivity of the submandibular ganglion and autonomic postganglionic fiber was most prominent and that of the ductal system was well concentrated in epithelial layer. eNOS or nNOS-positive immunoreactivity was not detected either in excretory ducts or in serous acinar cell. Inducible NOS-positive immunoreactivity was not seen. There results reveal the presence of eNOS and nNOS in the salivary gland, which may be related with regulation of the glandular secretion and blood flow.