Block of a voltage-activated Ca2+ channel current by phenobarbital (PHB), 5-(2-cyclohexylideneethyl)-5-ethyl barbituric acid (CHEB), and the optical R(-)- and S(+)-enantiomers of pentobarbital (PB) was examined in freshly dissociated adult guinea pig hippocampal CA1 neurons; the effects of the barbiturates on GABA-activated Cl- current were also characterized in the same preparation. (-)-PB, PH...

The negative chronotropic effects of eight Vaughan Williams Class I antiarrhythmic drugs were examined in guinea pig right atrial tissue preparations. decreased the spontaneous beating rate at concentrations overlapping with their therapeutic blood levels. Cibenzoline, aprindine, flecainide, and propafenone showed stronger effects; 10 µM each drug to about 75% initial values. Disopyramide, mexi...

Macroscopic and unitary currents through Ca(2+)-activated Cl- channels were examined in enzymatically isolated guinea-pig hepatocytes using whole-cell, excised outside-out and inside-out configurations of the patch-clamp technique. When K+ conductances were blocked and the intracellular Ca2+ concentration ([Ca2+]i) was set at 1 microM (pCa = 6), membrane currents were observed under whole-cell ...

The CIC family is the superfamily of voltage-gated Cl- channels. Although the CIC channels expressed in Xenopus oocytes have been characterized, their channel properties are still poorly understood. We recently cloned a unique member of the CIC family, CIC-3, that is expressed abundantly in neurons. Its channel activity was regulated by phorbol esters. Now, we have established a stably transfec...

The effect of mu-type opioid receptor agonist, D-Ala2,N-MePhe4,Gly5-ol-enkephalin (DAMGO), on high-voltage-activated (HVA) Ca2+ channels in the dissociated rat periaqueductal gray (PAG) neurons was investigated by the use of nystatin-perforated patch recording mode under voltage-clamp condition. Among 188 PAG neurons tested, the HVA Ca2+ channels of 38 neurons (32%) were inhibited by DAMGO (DAM...

There is strong evidence demonstrating that nifedipine dissolved in ethanol selectively inhibits only L-type Ca2+ current. In addition, acute ethanol exposure reduces voltage-dependent calcium currents. In the present study, we investigated the antagonistic effect of fixed concentration of nifedipine dissolved in different concentration of ethanol on L-type Ca2+ current. In a Na+-K+ free soluti...

Mice deficient in the smooth muscle Cav1.2 calcium channel (SMACKO, smooth muscle alpha1c-subunit calcium channel knockout) have a severely reduced micturition and an increased bladder mass. L-type calcium current, protein, and spontaneous contractile activity were absent in the bladder of SMACKO mice. K+ and carbachol (CCh)-induced contractions were reduced to 10-fold in detrusor muscles from ...

Voltage-dependent Ca2+ channels are a major pathway for Ca2+ entry in neurons. We have studied the electrophysiological, pharmacological, and molecular properties of voltage-gated Ca2+ channels in motoneurons of the rat facial nucleus in slices of the brainstem. Most facial motoneurons express both low voltage-activated (LVA) and high voltage-activated (HVA) Ca2+ channel currents. The HVA curre...

Single rat ventricular myocytes, voltage-clamped at -50 to -40 mV, were depolarized in small steps in order to define the mechanisms that govern the increase in cytosolic [Ca2+] (Cai) and contraction, measured as a reduction in myocyte length. Small (3-5 mV), sustained (seconds) depolarizations that caused a small inward or no detectable change in current were followed after a delay by small (l...

The activation of an anion channel in the plasma membrane of Arabidopsis thaliana hypocotyls by blue light (BL) is believed to be a signal-transducing event leading to growth inhibition. Here we report that the open probability of this particular anion channel depends on cytoplasmic Ca2+ ([Ca2+]cyt) within the concentration range of 1 to 10 microM, raising the possibility that BL activates the ...