[Inhibitory effects of tetraethylammonium on proliferation and voltage-gated potassium channels in human cervical carcinoma cell line SiHa].

Background & Objective: Various potassium channels are known to be involved in proliferation of many malignant cell lines. This study was to explore the role of voltage-gated potassium channels in proliferation of human cervical carcinoma cells through observing the effects of tetraethylammonium (TEA) on proliferation and outward potassium currents in human cervical carcinoma cell line SiHa.

Methods: SiHa cells were treated with TEA.

Effects of amiloride on potassium and calcium currents in guinea pig ventricular myocytes.

Aim: To elucidate the possible mechanisms underlying antiarrhythmia of the non-selective Na+/H+ exchanger inhibitor--amiloride.

Methods: Single ventricular cells were isolated using a double-enzyme method. Effects of amiloride on voltage-dependent potassium and calcium currents in isolated guinea pig ventricular myocyte were recorded by using whole-cell patch clamp techniques.

Inhibitory effects of berberine on ion channels of rat hepatocytes.

Aim: To examine the effects of berberine, an isoquinoline alkaloid with a long history used as a tonic remedy for liver and heart, on ion channels of isolated rat hepatocytes.

Methods: Tight-seal whole-cell patch-clamp techniques were performed to investigate the effects of berberine on the delayed outward potassium currents (I(K)), inward rectifier potassium currents (I(K1)) and Ca(2+) release-activated Ca(2+) currents (I(CRAC)) in enzymatically isolated rat hepatocytes.

Results: Berberine 1-300 micromol/L reduced I(K) in a concentration-dependent manner with EC(50) of 38.

[Effects of Rbl on action potentials and force of contraction in guinea pig ventricular papillary muscles].

Objective: To evaluate the effects of Rbl on action potentials and force of contraction in guinea pig ventricular papillary muscles.

Method: The ventricular papillary muscles of guinea pig were isolated regularly and immersed with Tyrode, s solution. The effects of Rbl (purified saponins of panaxnotoginseng) on the action potentials (AP), the slow action potentials and the force of contraction (FC) of the muscles were studied.

[Effect of ouabain on the aortic rings of guinea pig and its interactions with Ca2+, norepinephrine].

Aim: To observe the effects of ouabain on vascular smooth muscle (VSM) of the guinea pig and its interactions with Ca2+ and norepinephrine (NE).

Methods: Using isolated thoracic aortic ring of the guinea pig, the degrees of contractile activity of drugs were recorded.

Results: Ouabain showed a direct contractile effect in a concentration-dependent manner on thoracic aortic ring of guinea pig.

Effects of berberine on potassium currents in acutely isolated CA1 pyramidal neurons of rat hippocampus.

The effects of berberine, an isoquinoline alkaloid with antiarrhythmic action, on voltage-dependent potassium currents were studied in acutely isolated CA1 pyramidal neurons of rat hippocampus by using the whole-cell patch-clamp techniques. Berberine blocked transient outward potassium current (IA) and delayed rectifier potassium current (IK) in a concentration-dependent manner with EC50 of 22.94+/-4.

Electrophysiological effects of anthopleurin-Q on rat hepatocytes.

Aim: To study the effects of AP-Q on CCl(4)-induced acute liver injury, delayed outward potassium current (I(K)), inward rectifier potassium current (I(K1)) and calcium release-activated calcium current (I(CRAC)) in isolated rat hepatocytes.

Methods: A single dose of CCl(4) (10 microg/mL, ip) was injected to induce acute liver injury in rats. Serum aminotransferase activities were determined.

Perforated patch recording of L-type calcium current with beta-escin in guinea pig ventricular myocytes.

Aim: To establish a perforated patch recording (PPR) mode with beta-escin and compare L-type calcium current (I(Ca,L)) recorded under PPR and normal whole-cell recording (WCR) condition in isolated guinea-pig ventricular myocytes.

Methods: Single myocytes were dissociated by enzymatic dissociation method. beta-escin was added to the pipette solution to perforate the cell membrane and obtain PPR mode.

Effects of benzyltetrahydropalmatine on the rapidly activating component of delayed rectifier potassium current in guinea pig ventricular myocytes.

Aim: To investigate the effect of benzyltetrahydropalmatine (BTHP) on the rapidly activating component of delayed rectifier K+ current (Ikr) in single guinea pig ventricular myocytes.

Methods: Whole-cell patch clamp technique was used to record Ikr.

Results: Ikr was blocked by 1-100 mumol.

Effects of palmatine on potassium and calcium currents in isolated rat hepatocytes.

Aim: To study the effects of palmatine, a known inhibitor on delayed rectifier potassium current and L-type calcium current (I(Ca,L)) in guinea pig ventricular myocytes, on the potassium and calcium currents in isolated rat hepatocytes.

Methods: Tight-seal whole-cell patch-clamp techniques were performed to investigate the effects of palmatine on the delayed outward potassium currents (I(K)), inward rectifier potassium current (I(K1)) and Ca(2+) release-activated Ca(2+) current (I(CRAC)) in enzymatically isolated rat hepatocytes.

Results: Palmatine 0.

Effects of tetrandrine on calcium and potassium currents in isolated rat hepatocytes.

Aim: To study the effects of tetrandrine (Tet) on calcium release-activated calcium current (I(CRAC)), delayed rectifier potassium current (I(K)), and inward rectifier potassium currents (I(K1)) in isolated rat hepatocytes.

Methods: Hepatocytes of rat were isolated by using perfusion method. Whole cell patch-clamp techniques were used in our experiment.

Effects of tetrandrine on cardiovascular electrophysiologic properties.

Tetrandrine (Tet) is one of the best characterized Ca2+ channel blocker of plant origin. It can affect cardiovascular electrophysiologic properties in following field: inhibit the contractility, +/-dt/dpmax, and automaticity of myocardium, prolong the FRP, and exert concentration-dependent negative inotropic and chronotropic effects without altering cardiac excitability. Tet directly blocks both T-type and L-type calcium current in ventricular cells and vascular smooth muscle cells, but it does not shift the I-V relationship curve of ICa.

[Modulation of protein kinase A and protein kinase C on the delayed rectifier potassium current in guinea pig ventricular myocytes].

Aim: To study modulation of protein kinase A (PKA) and protein kinase C (PKC) on the delayed rectifier potassium current (Ik)in guinea pig ventricular myocytes.

Methods: The delayed rectifier potassium current was recorded by using whole cell arrangement of the patch-clamp procedure.

Results: cAMP 150 micromol/L increased intracellularly Ik and Ik,tail(pA/pF) from 13.

Effects of anthopleurin-Q on myocardial hypertrophy in rats and physiologic properties of isolated atria in guinea pigs.

Aim: To study effects of anthopleurin-Q (AP-Q) on myocardial hypertrophy in rats and isolated atria in guinea pigs.

Methods: Two myocardial hypertrophy models in rats were established, one introduced by levothyroxine, the other by stenosis of abdominal aorta. Cardiac myocytes morphometry and functional experiments were employed to investigate effects of AP-Q.

Effects of benzyltetrahydropalmatine on potassium currents in guinea pig and rat ventricular myocytes.

Aim: To investigate the effects of benzyltetrahydropalmatine (BTHP) on rapidly activating component (I(Kr)), slowly activating component (I(Ks)) of delayed rectifier potassium current, inward rectifier potassium current (I(K1)), and transient outward potassium current (I(to)) in single ventricular myocytes.

Methods: Whole-cell patch clamp technique was used to record ionic currents.

Results: (1) BTHP 30 micromol/L reduced I(Kr) and I(Kr,tail) by 31 %+/-4 % and 36 %+/-5 % (n=6, P <0.