The effects of pharmacological agents on the T-type Ca2+ current were studied in dissociated spermatogenic cells from the mouse. Ca2+ currents were elicited by depolarization in 10 mM Ca2+ and recorded in the whole-cell configuration of the patch clamp technique. The T-type current was inhibited by the following compounds: PN200-110 (IC50 = 4 x 10(-8) M) > nifedipine (IC50 = 4 x 10(-7) M) > pim...

Removal of Ca2+ from the solution bathing neurons is known in many cases to alter the gating properties of voltage-dependent K+ channels and to induce a large, nonselective "leak" conductance. We used a heterologous expression system to test whether the leak conductance observed in neurons is mediated by voltage-dependent K+ channels in an altered, debased conformation. Voltage-dependent K+ cha...

Previous studies suggested a role for calcium in CYP2E1-dependent toxicity. The possible role of phospholipase A2 (PLA2) activation in this toxicity was investigated. HepG2 cells that overexpress CYP2E1 (E47 cells) exposed to arachidonic acid (AA) +Fe-NTA showed higher toxicity than control HepG2 cells not expressing CYP2E1 (C34 cells). This toxicity was inhibited by the PLA2 inhibitors aristol...

The capping of Concanavalin A (Con A) receptors induced by Con A was studied using human peripheral blood lymphocytes. The effects of Con A dose (5--100 micrograms/ml), pretreatment at 4 degrees C, unbound Con A, extracellular Ca2+ and Mg2+ and vinblastine were evaluated using Con A-horseradish peroxidase and electron microscopy. Lymphocytes incubated with Con A at 4 degrees C and fixed with gl...

GT1-1 cells exhibit spontaneous action potentials and transient increases in intracellular calcium concentration ([Ca2+]i) that occur in individual cells and as spatially propagated intercellular Ca2+ waves. In this study, simultaneous cell-attached patch-clamp recording of action currents (indicative of action potentials) and fluorescence imaging of [Ca2+]i revealed that Ca2+ transients in GT1...

This study focuses on the ionic mechanisms involved in serotonergic control of the ventricle from the mollusc Mercenaria mercenaria. The effects of calcium (Ca2+), sodium (Na+), potassium (K+), magnesium (Mg2+) and chloride (Cl2) ions on the action of 5-hydroxytryptamine (5-HT) were tested using a sucrose-gap technique. 5-HT increased the amplitude and frequency of the cardiac action potentials...

a newly developed natural rubber deproteinization process produces deproteinized natural rubber (dpnr) wastewater as an intermediate product containing a high concentration of sodium dodecyl sulfate (sds) and rubber. in this study, a novel process to recover the residual rubber and energy as methane from dpnr wastewater was developed. as a pretreatment, sds and residual rubber in dpnr wastewate...

Microglial cells are activated in response to brain insults; the mechanisms of this process are not yet understood. One of the important signaling mechanisms that might be involved in microglia activation is related to changes in the intracellular calcium concentration ([Ca2+]i). Using fluo-3 microfluorimetry, we have found that external application of the complement fragment C5a (4-10 nM) indu...

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...

The lipophilic anion tetraphenylboron (TPB-) but not the lipophilic cation tetraphenylarsonium (TPA+) inhibited ATP-dependent Ca2+ accumulation by isolated sarcoplasmic reticulum. TPB- did not inhibit ATP hydrolysis but did induce Ca2+ release from preloaded vesicles. It did not appear to disrupt lipid bilayers or to act as a Ca2+ ionophore since it had no effect on the Ca2+ content of phosphol...