Linked Life Data

1720449

Source:http://linkedlifedata.com/resource/pubmed/id/1720449

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1992-1-6
pubmed:abstractText
cAMP-activated Na+ current (INa,cAMP) was studied in voltage-clamped neurons of the seaslug Pleurobranchaea californica. The current response to injected cAMP varied in both time course and amplitude as the tip of an intracellular injection electrode was moved from the periphery to the center of the neuron soma. The latency from injection to peak response was dependent on the amount of cAMP injected unless the electrode was centered within the cell. Decay of the INa,cAMP response was slowed by phosphodiesterase inhibition. These observations suggest that the kinetics of the INa,cAMP response are governed by cAMP diffusion and degradation. Phosphodiesterase inhibition induced a persistent inward current. At lower concentrations of inhibitor, INa,cAMP response amplitude increased as expected for decreased hydrolysis rate of injected cAMP. Higher inhibitor concentrations decreased INa,cAMP response amplitude, suggesting that inhibitor-induced increase in native cAMP increased basal INa,cAMP and thus caused partial saturation of the current. The Hill coefficient estimated from the plot of injected cAMP to INa,cAMP response amplitude was close to 1.0. An equation modeling INa,cAMP incorporated terms for diffusion and degradation. In it, the first-order rate constant of phosphodiesterase activity was taken as the rate constant of the exponential decay of the INa,cAMP response. The stoichiometry of INa,cAMP activation was inferred from the Hill coefficient as 1 cAMP/channel. The equation closely fitted the INa,cAMP response and simulated changes in the waveform of the response induced by phosphodiesterase inhibition. With modifications to accommodate asymmetric INa,cAMP activation, the equation also simulated effects of eccentric electrode position. The simple reaction-diffusion model of the kinetics of INa,cAMP may provide a useful conceptual framework within which to investigate the modulation of INa,cAMP by neuromodulators, intracellular regulatory factors, and pharmacological agents.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0022-1295
pubmed:author
pubmed:issnType
Print
pubmed:volume
98
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
835-48
pubmed:dateRevised
2008-11-20
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Kinetic analysis of cAMP-activated Na+ current in the molluscan neuron. A diffusion-reaction model.
pubmed:affiliation
Department of Physiology and Biophysics, University of Illinois, Urbana 61801.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.