Functional roles of sodium-calcium exchange in autorhythmicity and action potential of murine fetal cardiomyocytes at early developmental stage.

The aim of the present paper was to study the role of sodium calcium exchanger (NCX) in the generation of action potentials (APs) in cardiomyocytes during early developmental stage (EDS). The precisely dated embryonic hearts of C57 mice were dissected and enzymatically dissociated to single cells. The changes of APs were recorded by whole-cell patch-clamp technique before and after administration of NCX specific blockers KB-R7943 (5 μmol/L) and SEA0400 (1 μmol/L).

MiR-20 regulates myocardiac ischemia by targeting KATP subunit Kir6.1.

This study aimed to examine the functional role of microRNA-20 (miR-20) and its potential target, Kir6.1, in ischemic myocardiocytes. The expression of miR-20 was detected by real-time PCR.

Thymosin β4 impeded murine stem cell proliferation with an intact cardiovascular differentiation.

Thymosin β4 (Tβ4) is a key factor in cardiac development, growth, disease, epicardial integrity, blood vessel formation and has cardio-protective properties. However, its role in murine embryonic stem cells (mESCs) proliferation and cardiovascular differentiation remains unclear. Thus we aimed to elucidate the influence of Tβ4 on mESCs.

[Expression of Kir2.1, SCN5a and SCN1b channel genes in mouse cardiomyocytes with various electric properties: patch clamp combined with single cell RT-PCR study].

This study is to explore a new method of investigating molecular basis for electrophysiological properties of early fetal cardiomyocytes. Single embryonic cardiomyocytes of mouse early developmental heart (E10.5) were obtained by a collagenase B digestion approach.

Hyposmotic challenge modulates function of L-type calcium channel in rat ventricular myocytes through protein kinase C.

Aim: To study the effects and mechanisms by which hyposmotic challenge modulate function of L-type calcium current (I(Ca,L)) in rat ventricular myocytes.

Methods: The whole-cell patch-clamp techniques were used to record I(Ca,L) in rat ventricular myocytes.

Results: Hyposmotic challenge(∼220 mosmol/L) induced biphasic changes of I(Ca,L), a transient increase followed by a sustained decrease.

An optimized recording method to characterize biophysical and pharmacological properties of acid-sensing ion channel.

Objective: To re-confirm and characterize the biophysical and pharmacological properties of endogenously expressed human acid-sensing ion channel 1a (hASIC1a) current in HEK293 cells with a modified perfusion methods.

Methods: With cell floating method, which is separating the cultured cell from coverslip and putting the cell in front of perfusion tubing, whole cell patch clamp technique was used to record hASIC1a currents evoked by low pH external solution.

Results: Using cell floating method, the amplitude of hASIC1a currents activated by pH 5.

Role of transient receptor potential vanilloid 4 in the effect of osmotic pressure on myocardial contractility in rat.

The aim of the present study was to investigate the influence of osmotic pressure on myocardial contractility and the possible mechanism. Electrical stimulation was used to excite papillary muscles of the left ventricle of Sprague-Dawley (SD) rats. The contractilities of myocardium in hyposmotic, isosmotic, and hyperosmotic perfusates were recorded.

Cannabinoids inhibit ATP-activated currents in rat trigeminal ganglionic neurons.

The present study aimed to investigate whether cannabinoids could modulate the response mediated by ATP receptor (P2X purinoceptor). Whole-cell patch-clamp recording was performed on cultured rat trigeminal ganglionic (TG) neurons. The majority of TG neurons were sensitive to ATP (67/75, 89.

[Effects of melatonin on the induction of long term potentiation in the hippocampal CA3 area of rats].

Aim: To study the effect of melatonin on the induction of LTP in CA3 area of hippocampus and to investigated its possible mechanisms.

Methods: Melatonin and other drugs (Tacrine or DNQX) were microinjected into the CA3 area. By using extracellular electrophysiological recordings to observe the changes of the slope of fEPSP in the CA3 area.

Effect of hypoxia on hyperpolarization-activated current in mouse dorsal root ganglion neurons.

The properties of hyperpolarization-activated current (I(h)) in mouse dorsal root ganglion (DRG) neurons and the effect of hypoxia on the current have been studied using whole-cell configuration of the patch clamp technique. Under voltage-clamp mode, I(h), blocked by 1 mM extracellular CsCl, was present in 75.5% of mouse DRG neurons.

Action of beta-amyloid peptide₁₋₄₀ on I(HVA) and its modulation by ginkgolide B.

Whole-cell patch clamp recording was used to investigate the action of beta-amyloid peptide(1-40) (Abeta(1-40)) on high voltage-activated calcium channel current (I(HVA)) in acutely isolated hippocampal CA1 pyramidal neurons in rats and observe its modulation by ginkgolide B (GB). Drug was applied by extracellular bath or adding in the pipette solution, and its effect was determined by comparing the amplitude of I(HVA) before and after the drug application. Bath application of aggregated Abeta(1-40) at concentrations of 0.

[An electrophysiological study on the artificial somato-autonomic pathway for inducing voiding].

Objective: To investigate the possibility of regeneration of somatic motor nerve to replace splanchnic nerve and the electrophysiologic characters of the regenerated nerve.

Methods: An artificial somato-autonomic reflex pathway was established by intradural microanastomosis of L(4) ventral root (VR) to L(6)VR at the left side in 12 male Wistar rats. Then the L(4)VR proximal to the anastomosis was stimulated by silver electrode and the evoked potentials were recorded on the distal end to the anastomosis, pelvic nerve and postganlionic fibers of the major pelvic ganglia (MPG).

Action of aluminum on high voltage-dependent calcium current and its modulation by ginkgolide B.

Aim: To investigate the effect of aluminum (Al) on high voltage-dependent calcium current (I(HVA)) and its modulation by ginkgolide B (Gin B).

Methods: The whole-cell, patch-clamp technique was used to record IHVA from acutely isolated hippocampal CA1 pyramydal neurons in rats.

Results: Al 0.

Different signal molecules involved in the muscarinic modulation of pacemaker current I(f) on the heart of mouse embryo in different developmental stages.

We isolated mouse embryonic cardiomyocytes derived from timed-pregnant females at different periods and used patch-clamp technique to investigate the muscarinic cholinergic modulation of pacemaker current I(f) in different developmental stages. In early development stage (EDS), muscarinic agonist carbachol (CCh) significantly decreased the magnitude of the pacemaker current I(f) but had no effect in late development stage (LDS). Forskolin (a direct adenylate cyclase activator) and IBMX (a non-selective phosphodiesterase inhibitor) increased I(f) in both EDS and LDS cells.

Muscarinic cholinergic regulation of L-type calcium channel in heart of embryonic mice at different developmental stages.

Aim: To investigate the muscarinic regulation of L-type calcium current (I(Ca-L)) during development.

Methods: The whole cell patch-clamp technique was used to record II(Ca-L) in mice embryonic cardiomyocytes at different stages (the early developmental stage, EDS; the intermediate developmental stage, IDS; and the late developmental stage, LDS). Carbachol (CCh) was used to stimulate M-receptor in the embryonic cardiomyocytes of mice.

[Isolation and electrophysiological characteristics of embryonic cardiomyocytes in mice].

To explore the electrophysiological characteristics of embryonic cardiomyocytes, single embryonic cardiomyocytes were obtained from mice at different periods by a collegenase B digestion approach, whole cell patch clamp recording technique was used to record I(f) and I(Ca-L), and spontaneous action potential was also recorded. The morphological and spontaneous contractile properties of the isolated cells appeared to be typical embryonic cardiomyocytes when the cells were assessed by phase-contrast microscope. Whole cell recording of isolated cells is easily performed by the whole cell patch clamp technique.

[Chronic intermittent hypoxia decreases acute hypoxic inhibition of voltage-gated potassium channel in rat pulmonary arterial smooth muscle cells].

For determination the ionic mechanisms of the hypoxic acclimatization at the level of channels, male Spradue-Dawley rats were divided into two groups: control normoxic group and chronic intermittent hypoxic group [O2 concentration: (10 +/-0.5)%, hypoxia 8 h a day]. Using whole cell patch-clamp technique, voltage-gated potassium channel currents (IK(V)) were recorded in freshly isolated pulmonary arterial smooth muscle cells (PASMCs) of rat with acute isolated method.

Effects of platelet activating factor on action potentials and potassium channels in guinea-pig ventricular myocytes.

This study was designed to investigate the effects of platelet activating factor (PAF) on the action potential and potassium currents in guinea-pig ventricular myocytes. Whole cell patch clamp techniques were used. With 5 mmol/L ATP in the pipette electrode(mimic normal condition), 1 micromol/L PAF increased APD(90) from 225.

[Influence of PAF receptors on long term potentiation attenuated by aluminium in hippocampal CA3 area of rats].

Aim: To investigate the influence of platelet-activating factor (PAF) receptor on long-term potentiation (LTP) attenuated by aluminium.

Methods: The method of extracellular recording was used to investigate the effect of PAF receptors on PP-CA3 LTP by microinjection of PAF receptor antagonist Ginkgolide B or agonist mc-PAF into CA3 area.

Results: (1) Amplitude of population spikes (PS) of evoked potential was not affected but LTP induction was blocked by 0.

Developmental changes in functional expression and beta-adrenergic regulation of I(f) in the heart of mouse embryo.

The hyperpolarization-activated current (I(f)) plays an important role in determining the spontaneous rate of cardiac pacemaker cells. The automatic rhythmicity also exists in working cells of embryonic heart, therefore we studied developmental changes in functional expression and beta-adrenergic regulation of I(f) in embryonic mouse heart. The expression of I(f) is high in early developmental stage (EDS) (10.

Inhibitory effect of adrenomedullin on L-type calcium currents in guinea-pig ventricular myocytes.

The effects of adrenomedullin (ADM) on the L-type calcium currents (I(Ca,L)) and the mechanism of the signal transduction process were studied. Enzymatically isolated guinea-pig ventricular myocytes were used to measure ICa,L with whole-cell patch-clamp techniques. ADM at the concentrations of 1-100 nmol/L decreased ICa,L in a dose-dependent manner (P<0.