Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1974-12-6
pubmed:abstractText
Hauswirth et al. (1968) proposed that epinephrine acts on i(KK2) by adding its own positive charge to the external membrane surface near the i(KK2) channel. This hypothesis was tested by using noncationic compounds, theophylline and R07-2956, which mimicked epinephrine's effects on pacemaker activity and on i(KK2). In maximally effective doses, theophylline or R07-2956 occluded the effect of epinephrine, indicating a shared final common mechanism. Since theophylline and R07-2956 are noncationic at pH 7.4, the common mechanism cannot be a direct change in external surface charge. On the contrary, epinephrine does not interfere with the voltage shift produced by La(+++), which is thought to modify the external surface charge. The results argue against the original hypothesis but leave open the possibility that an alteration in internal surface charge generates the observed voltage shift. The potency of theophylline and R07-2956 as phosphodiesterase inhibitors suggests that the final common mechanism begins with the elevation of intracellular cyclic AMP, leading to a saturable process which limits the voltage shift's magnitude. This hypothesis is used to generate dose-response curves describing the combined effects of epinephrine and theophylline, and these are compared with experimental data.
pubmed:commentsCorrections
http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-13264118, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-13449875, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-13654742, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-13777928, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-13904633, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-13990605, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-4310439, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-4343950, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-4347149, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-4386717, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-4401230, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-4413132, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-4736776, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-5552247, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-5639799, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-5648068, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-5780717, http://linkedlifedata.com/resource/pubmed/commentcorrection/4370200-5835697
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0022-1295
pubmed:author
pubmed:issnType
Print
pubmed:volume
64
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
320-42
pubmed:dateRevised
2010-6-22
pubmed:meshHeading
pubmed:year
1974
pubmed:articleTitle
Mode of action of chronotropic agents in cardiac Purkinje fibers. Does epinephrine act by directly modifying the external surface charge?
pubmed:publicationType
Journal Article, In Vitro