5-Hydroxytryptamine (5-HT) is proarrhythmic in atrial cells from patients in sinus rhythm (SR) via activation of 5-HT(4) receptors, but its effects in atrial cells from patients with atrial fibrillation (AF) are unknown. The whole-cell perforated patch-clamp technique was used to record L-type Ca(2+) current (I(CaL)), action potential duration (APD) and arrhythmic activity at 37 degrees C in en...

The mouse heart has become a widely used model for genetic studies of heart diseases. Thus, understanding gender differences in mouse cardiac repolarization is crucial to the interpretation of such studies. The objective of this study was to evaluate whether there are gender differences in cardiac repolarization in mouse ventricle and to gain insights into the ionic and molecular mechanisms und...

We have examined the ability of BI (class A) Ca2+ channels, cloned from rabbit brain, to mediate excitation-contraction (E-C) coupling in skeletal muscle. Expression plasmids carrying cDNA encoding BI channels were microinjected into the nuclei of dysgenic mouse myotubes grown in primary culture. Ionic currents and intramembrane charge movements produced by the BI channels were recorded using t...

1. The effects of clonidine and adrenaline on adenosine 5'-triphosphate (ATP)-sensitive K+ channels were studied in pancreatic beta-cells from normal mice. 2. When perifused with a medium containing 1 mM glucose, many of the ATP-sensitive K+ channels in the beta-cell membrane are open. Under these conditions, clonidine (5-100 microM) reversibly decreased 86Rb efflux from the islets, whereas adr...

A physiological role of carbon monoxide has been suggested for coronary myocytes; however, direct evidence is lacking. The objective of this study was to test the effect of chronic carbon monoxide exposure on the K(+) currents of the coronary myocytes. The effect of 3-wk chronic exposure to carbon monoxide was assessed on K(+) currents in isolated rat left coronary myocytes by the use of the pa...

We used molecular biological and patch-clamp techniques to identify the Ca(2+)-activated K(+) channel genes in mouse parotid acinar cells. Two types of K(+) channels were activated by intracellular Ca(2+) with single-channel conductance values of 22 and 140 pS (in 135 mM external K(+)), consistent with the intermediate and maxi-K classes of Ca(2+)-activated K(+) channels, typified by the mIK1 (...

Muscarinic modulation of calcium currents was studied in acutely isolated striatal neurons from the adult rat using the whole-cell configuration of the patch-clamp technique. Muscarinic agonists reduced calcium currents through two distinct signaling pathways. One pathway depended upon PTX-sensitive G-proteins and targeted N- and P-type currents. The other pathway depended upon PTX-insensitive ...

The contribution of Ca2(+)-activated and delayed rectifying K+ channels to the voltage-dependent outward current involved in spike repolarization in mouse pancreatic beta-cells (Rorsman, P., and G. Trube. 1986. J. Physiol. 374:531-550) was assessed using patch-clamp techniques. A Ca2(+)-dependent component could be identified by its rapid inactivation and sensitivity to the Ca2+ channel blocker...

OBJECTIVE The aim of this study was to analyze the effects of loratadine on a human cardiac K+ channel (hKv1.5) cloned from human ventricle and stably expressed in a mouse cell line. METHODS Currents were studied using the whole-cell configuration of the patch-clamp technique in Ltk- cells transfected with the gene encoding hKv1.5 channels. RESULTS Loratadine inhibited in a concentration-de...

The effects of nano particles of CuO on voltage-dependent potassium currents were studied in acutely isolated CA1 pyramidal neurons of rat hippocampus using the whole-cell patch-clamp techniques. Nano particles of CuO had small effects on transient outward potassium current (I(A), no statistical significance) and mainly inhibited delayed rectifier potassium current (I(K)) in the concentration o...