Afterhyperpolarization induced by the activation of nicotinic acetylcholine receptors in pelvic ganglion neurons of male rats.

The electrophysiological mechanism underlying afterhyperpolarization induced by the activation of the nicotinic acetylcholine receptor (nAChR) in male rat major pelvic ganglion neurons (MPG) was investigated using a gramicidin-perforated patch clamp and microscopic fluorescence measurement system. Acetylcholine (ACh) induced fast depolarization through the activation of nAChR, followed by a sustained hyperpolarization after the removal of ACh in a dose-dependent manner (10 microM to 1mM). ACh increased both intracellular Ca(2+) ([Ca(2+)](i)) and Na(+) concentrations ([Na(+)](i)) in MPG neurons.

Dual effect of ATP on glucose-induced insulin secretion in HIT-T15 cells.

Objectives: : The study investigated the dual effect of purinergic nucleotides on the secretion of insulin from pancreatic beta cells.

Methods: : The level of insulin secretion in HIT-T15 cells of static incubation was measured using a radioimmunoassay.

Results: : The adenine nucleotides reduced the level of glucose-induced insulin secretion in a concentration-dependent manner, and the relative potency order (IC50; muM) was BzATP (6.

Changes in inward rectifier K+ channels in hepatic stellate cells during primary culture.

Purpose: This study examined the expression and function of inward rectifier K(+) channels in cultured rat hepatic stellate cells (HSC).

Materials And Methods: The expression of inward rectifier K(+) channels was measured using real-time RT-PCR, and electrophysiological properties were determined using the gramicidin-perforated patch-clamp technique.

Results: The dominant inward rectifier K(+) channel subtypes were K(ir)2.

Calcium mobilization by activation of M(3)/M(5) muscarinic receptors in the human retinoblastoma.

Activation of muscarinic acetylcholine receptors (mAChR) is one of the most important signal transduction pathways in the human body. In this study, we investigated the role of mAChR activation in relation to its subtypes in human retinoblastoma cell-lines (WERI-Rb-1) using Ca(2+) measurement, real-time PCR, and Western Blot techniques. Acetylcholine (ACh) produced prominent [Ca(2+)](i) transients in a repeated manner in WERI-Rb-1 cells.

Characteristics of P2X7-like receptor activated by adenosine triphosphate in HIT-T15 cells.

Objectives: The study examined the presence of a P2X7 receptor subtype and its functional roles in pancreatic beta cells.

Methods: In a hamster beta-cell line, HIT-T15 cells, purinergic stimulation was investigated using fluorometry, electrophysiology, flow cytometry, and electrophoresis.

Results: Adenosine triphosphate (ATP) and 2'-3'-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate (BzATP) increased in the intracellular free Ca2+ concentration, with an EC50 of 398.

An alpha3beta4 subunit combination acts as a major functional nicotinic acetylcholine receptor in male rat pelvic ganglion neurons.

We identified major subunits of the nicotinic acetylcholine receptor (nAChR) involved in excitatory postsynaptic potential and intracellular Ca(2+) ([Ca(2+)]i) increase in the major pelvic ganglion (MPG) neurons of the male rat. ACh elicited fast inward currents in both sympathetic and parasympathetic MPG neurons. Mecamylamine, a selective antagonist for alpha3beta4 nAChR, potently inhibited the ACh-induced currents in sympathetic and parasympathetic neurons (IC(50); 0.

Expression profiles of high voltage-activated calcium channels in sympathetic and parasympathetic pelvic ganglion neurons innervating the urogenital system.

Among the autonomic ganglia, major pelvic ganglia (MPG) innervating the urogenital system are unique because both sympathetic and parasympathetic neurons are colocalized within one ganglion capsule. Sympathetic MPG neurons are discriminated from parasympathetic ones by expression of low voltage-activated Ca2+ channels that primarily arise from T-type alpha1H isoform and contribute to the generation of low-threshold spikes. Until now, however, expression profiles of high voltage-activated (HVA) Ca2+ channels in these two populations of MPG neurons remain unknown.

Nerve injury alters profile of receptor-mediated Ca2+ channel modulation in vagal afferent neurons of rat nodose ganglia.

Although nerve injury is known to up- and down-regulate some metabotropic receptors in vagal afferent neurons of the nodose ganglia (NG), the functional significance has not been elucidated. In the present study, thus, we examined whether nerve injury affected receptor-mediated Ca2+ channel modulation in the NG neurons. In this regard, unilateral vagotomy was performed using male Sprague-Dawley rats.

Divalent metals differentially block cloned T-type calcium channels.

We tested divalent metals including Cu2+, Pb2+, and Zn2+ to determine their pharmacological profiles for blockade of cloned T-type Ca2+ channels (alpha1G, alpha1 H, and alpha1I). Effects of the metals were also evaluated for native low and high voltage-activated Ca2+ channels in rat sympathetic pelvic neurons. Cu2+ and Zn2+ blocked three T-type channel isoforms in a concentration-dependent manner with a higher affinity for alpha1H currents (IC50 = 0.

Identification of T-type alpha1H Ca2+ channels (Ca(v)3.2) in major pelvic ganglion neurons.

Among autonomic neurons, sympathetic neurons of the major pelvic ganglia (MPG) are unique by expressing low-voltage-activated T-type Ca2+ channels. To date, the T-type Ca2+ channels have been poorly characterized, although they are believed to be potentially important for functions of the MPG neurons. In the present study, thus we investigated characteristics and molecular identity of the T-type Ca2+ channels using patch-clamp and RT-PCR techniques.