Voltage Regulation
Mostrando 49-60 de 352 artigos, teses e dissertações.
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49. Identification and regulation of the cystic fibrosis transmembrane conductance regulator-generated chloride channel.
Cystic fibrosis transmembrane conductance regulator (CFTR) generates cAMP-regulated Cl- channels; mutations in CFTR cause defective Cl- channel function in cystic fibrosis epithelia. We used the patch-clamp technique to determine the single channel properties of Cl- channels in cell expressing recombinant CFTR. In cell-attached patches, an increase in cellul
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50. Activation of normal and cystic fibrosis Cl- channels by voltage, temperature, and trypsin.
In cystic fibrosis (CF) phosphorylation-dependent activation of outwardly rectifying apical membrane Cl- channels is defective. To further understand regulation of this channel we examined several other mechanisms of channel activation in normal and CF cells. Previous studies have shown that strong membrane depolarization can activate channels in excised cel
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51. Controlling potassium channel activities: Interplay between the membrane and intracellular factors
Neural signaling is based on the regulated timing and extent of channel opening; therefore, it is important to understand how ion channels open and close in response to neurotransmitters and intracellular messengers. Here, we examine this question for potassium channels, an extraordinarily diverse group of ion channels. Voltage-gated potassium (Kv) chan
The National Academy of Sciences.
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52. Modulation of K+ currents in human lymphocytes by pH.
1. Using whole-cell patch-clamp techniques, we found that the voltage-dependent K+ conductance in human peripheral blood T lymphocytes is enhanced threefold at alkaline intracellular pH (pHi) compared to acid pHi. This pH dependence can be described by a model having two strongly co-operative proton binding sites with pka 7.15. A similar pHi sensitivity exis
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53. Voltage window for sustained elevation of cytosolic calcium in smooth muscle cells.
Action potentials activate voltage-dependent calcium channels and attendant increases in cytosolic calcium concentration ([Ca2+]i) in many excitable cells. The role of these channels in the regulation of [Ca2+]i in nonspiking cells that do not depolarize to membrane potentials sufficient to activate a substantial fraction of the available current is less cle
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54. Large conductance voltage- and calcium-dependent K+ channel, a distinct member of voltage-dependent ion channels with seven N-terminal transmembrane segments (S0-S6), an extracellular N terminus, and an intracellular (S9-S10) C terminus
Large conductance voltage- and Ca2+-dependent K+ (MaxiK) channels show sequence similarities to voltage-gated ion channels. They have a homologous S1-S6 region, but are unique at the N and C termini. At the C terminus, MaxiK channels have four additional hydrophobic regions (S7-S10) of unknown topology. At the N terminus, we have recently proposed a new mode
The National Academy of Sciences of the USA.
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55. Adenosine agonists reduce voltage-dependent calcium conductance of mouse sensory neurones in cell culture.
Adenosine and several of its analogues produced a concentration-dependent shortening of calcium-dependent action potential (c.a.p.) duration of mouse dorsal root ganglion (d.r.g.) neurones in dissociated cell culture. The following rank order of potency was obtained: N6-(L-phenylisopropyl)adenosine greater than N6-(D-phenylisopropyl)adenosine greater than N6
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56. Dual regulation of Ca2+/calmodulin-dependent kinase II activity by membrane voltage and by calcium influx.
Calcium entry through voltage-gated Ca2+ channels is critical in cardiac excitation-contraction coupling and calcium metabolism. In this report, we demonstrate both spatially resolved and temporally distinct effects of Ca2+/calmodulin-dependent protein kinase II (CaMKII) on L-type Ca2+ channel current (ICa) in rat cardiac myocytes. Either depolarization alon
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57. Lack of regulation by intracellular Ca2+ of the hyperpolarization-activated cation current in rat thalamic neurones.
1. The regulation of the hyperpolarization-activated cation current, Ih, in thalamocortical neurones by intracellular calcium ions has been implemented in a number of mathematical models on the waxing and waning behaviour of synchronized rhythmic activity in thalamocortical circuits. In the present study, the Ca2+ dependence of Ih in thalamocortical neurones
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58. Oxygen-sensitive calcium channels in vascular smooth muscle and their possible role in hypoxic arterial relaxation.
We have investigated the modifications of cytosolic [Ca2+] and the activity of Ca2+ channels in freshly dispersed arterial myocytes to test whether lowering O2 tension (PO2) directly influences Ca2+ homeostasis in these cells. Unclamped cells loaded with fura-2 AM exhibit oscillations of cytosolic Ca2+ whose frequency depends on extracellular Ca2+ influx. Sw
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59. Cloning and functional expression of a plant voltage-dependent chloride channel.
Plant cell membrane anion channels participate in basic physiological functions, such as cell volume regulation and signal transduction. However, nothing is known about their molecular structure. Using a polymerase chain reaction strategy, we have cloned a tobacco cDNA (CIC-Nt1) encoding a 780-amino acid protein with several putative transmembrane domains. C
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60. The effects of beta-stimulation on the Na(+)-K+ pump current-voltage relationship in guinea-pig ventricular myocytes.
1. The whole cell patch clamp technique was used to study effects of the beta agonist isoprenaline (Iso) on the current-voltage (I-V) relationship of the Na(+)-K+ pump current (Ip) in acutely isolated guinea-pig ventricular myocytes. 2. The effect of Iso on Ip at high [Ca2+]i (1.4 microM) was voltage dependent. The I-V relationship of Ip in Iso shifted by ap