Ni 2+ Slows the Activation Kinetics of High-Voltage-Activated Ca 2+ Currents in Cortical Neurons: Evidence for a Mechanism of Action Independent of Channel-Pore Block

2001 ◽  
Vol 179 (3) ◽  
pp. 243-262 ◽  
Author(s):  
J. Magistretti ◽  
S. Brevi ◽  
M. de Curtis
Keyword(s):  
Mechanism Of Action ◽  
High Voltage ◽  
Cortical Neurons ◽  
Activation Kinetics ◽  
Channel Pore ◽  
Kinetics Of

scholarly journals Mixing state and compositional effects on CCN activity and droplet growth kinetics of size-resolved CCN in an urban environment

2012 ◽  
Vol 12 (21) ◽  
pp. 10239-10255 ◽  
Author(s):  
L. T. Padró ◽  
R. H. Moore ◽  
X. Zhang ◽  
N. Rastogi ◽  
R. J. Weber ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Water Soluble ◽  
Anthropogenic Sources ◽  
Droplet Growth ◽  
Mixing State ◽  
Aerosol Composition ◽  
Activation Kinetics ◽  
Aerosol Mixing State ◽  
Kinetics Of ◽  
Ccn Activity

Abstract. Aerosol composition and mixing state near anthropogenic sources can be highly variable and can challenge predictions of cloud condensation nuclei (CCN). The impacts of chemical composition on CCN activation kinetics is also an important, but largely unknown, aspect of cloud droplet formation. Towards this, we present in-situ size-resolved CCN measurements carried out during the 2008 summertime August Mini Intensive Gas and Aerosol Study (AMIGAS) campaign in Atlanta, GA. Aerosol chemical composition was measured by two particle-into-liquid samplers measuring water-soluble inorganic ions and total water-soluble organic carbon. Size-resolved CCN data were collected using the Scanning Mobility CCN Analysis (SMCA) method and were used to obtain characteristic aerosol hygroscopicity distributions, whose breadth reflects the aerosol compositional variability and mixing state. Knowledge of aerosol mixing state is important for accurate predictions of CCN concentrations and that the influence of an externally-mixed, CCN-active aerosol fraction varies with size from 31% for particle diameters less than 40 nm to 93% for accumulation mode aerosol during the day. Assuming size-dependent aerosol mixing state and size-invariant chemical composition decreases the average CCN concentration overprediction (for all but one mixing state and chemical composition scenario considered) from over 190–240% to less than 20%. CCN activity is parameterized using a single hygroscopicity parameter, κ, which averages to 0.16 ± 0.07 for 80 nm particles and exhibits considerable variability (from 0.03 to 0.48) throughout the study period. Particles in the 60–100 nm range exhibited similar hygroscopicity, with a κ range for 60 nm between 0.06–0.076 (mean of 0.18 ± 0.09). Smaller particles (40 nm) had on average greater κ, with a range of 0.20–0.92 (mean of 0.3 ± 0.12). Analysis of the droplet activation kinetics of the aerosol sampled suggests that most of the CCN activate as rapidly as calibration aerosol, suggesting that aerosol composition exhibits a minor (if any) impact on CCN activation kinetics.

Investigating the Activation Kinetics of Phosphoramidites for Oligonucleotide Synthesis

2021 ◽  
Author(s):  
Fiona J. Laraman ◽  
Heidi Fisk ◽  
David T. E. Whittaker ◽  
Janette H. Cherryman ◽  
Louis J. Diorazio
Keyword(s):  
Oligonucleotide Synthesis ◽  
Activation Kinetics ◽  
Kinetics Of

Extracellular ATP selectively modulates a high-voltage-activated calcium conductance in salivary gland cells of the leech Haementeria ghilianii

1993 ◽  
Vol 181 (1) ◽  
pp. 313-319
Author(s):  
WA Wuttke ◽  
MS Berry
Keyword(s):  
Salivary Gland ◽  
High Voltage ◽  
Cyclic Gmp ◽  
Cyclic Nucleotides ◽  
Extracellular Atp ◽  
Salivary Gland Cells ◽  
Selective Modulation ◽  
Voltage Dependent ◽  
Kinetics Of ◽  
Higher Doses

Extracellular ATP appears to have a widespread role as a neurotransmitter or neuromodulator in mammals (Gordon, 1986; Burnstock, 1990), but little is known about any similar functions in invertebrates. During studies of the effects of cyclic nucleotides on electrically excitable salivary cells of the leech, we found that cyclic GMP produced a rapid (less than 1min) reduction of spike duration, suggesting an extracellular effect (Wuttke and Berry, 1991). We now show that micromolar concentrations of ATP (and higher doses of other nucleotides) also reduce spike duration, and that this is caused by depression of a specific voltage-dependent Ca2+ conductance. Selective modulation of Ca2+ current by external ATP has rarely been found, and the effect is also unusual because it changes the kinetics of inactivation rather than those of activation.

scholarly journals Activation Kinetics of AMPA Receptor Channels Reveal the Number of Functional Agonist Binding Sites

1998 ◽  
Vol 18 (1) ◽  
pp. 119-127 ◽  
Author(s):  
John D. Clements ◽  
Anne Feltz ◽  
Yoshinori Sahara ◽  
Gary L. Westbrook
Keyword(s):  
Ampa Receptor ◽  
Binding Sites ◽  
Agonist Binding ◽  
Activation Kinetics ◽  
Kinetics Of ◽  
Ampa Receptor Channels
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