Switch to
Predicate | Object |
---|---|
rdf:type | |
lifeskim:mentions | |
pubmed:issue |
2 Pt 1
|
pubmed:dateCreated |
1997-4-24
|
pubmed:abstractText |
Physiological roles of Ca2+ vs. Na+ in membrane currents and action potentials of ureteral myocytes were investigated on freshly dissociated guinea pig ureteral myocytes with the patch-clamp method. The myocytes are spindle shaped, with cell volume of 2,473 microm3, surface area of 2,014 microm2, capacitance of 48.2 pF, resting potential of -47.9 mV, and membrane conductance of 840 pS. The membrane current consists of a slow inward Ca2+ current (ICa) conducted by L-type Ca2+ channels and an actively fluctuating Ca2+-activated K+ current [IK(Ca)] conducted by Ca2+-activated maxi-K+ channels. ICa dominates the membrane current by being long lasting and more active at less depolarized potentials than IK(Ca) and by regulating IK(Ca). Ca2+-free media, Co2+, and nifedipine reduce or block ICa, whereas high extracellular Ca2+ concentration and BAY K 8644 enhance it. Action potential amplitudes and plateaus are regulated correspondingly. Related changes are also seen in IK(Ca) In contrast, no fast inward current attributable to Na+ was found. Replacing extracellular Na+ with tris(hydroxymethyl)aminomethane had no apparent effects on the inward or outward current or on the action potentials.
|
pubmed:grant | |
pubmed:language |
eng
|
pubmed:journal | |
pubmed:citationSubset |
IM
|
pubmed:chemical | |
pubmed:status |
MEDLINE
|
pubmed:month |
Feb
|
pubmed:issn |
0002-9513
|
pubmed:author | |
pubmed:issnType |
Print
|
pubmed:volume |
272
|
pubmed:owner |
NLM
|
pubmed:authorsComplete |
Y
|
pubmed:pagination |
C535-42
|
pubmed:dateRevised |
2007-11-14
|
pubmed:meshHeading |
pubmed-meshheading:9124296-Action Potentials,
pubmed-meshheading:9124296-Animals,
pubmed-meshheading:9124296-Calcium,
pubmed-meshheading:9124296-Electric Conductivity,
pubmed-meshheading:9124296-Extracellular Space,
pubmed-meshheading:9124296-Female,
pubmed-meshheading:9124296-Guinea Pigs,
pubmed-meshheading:9124296-Male,
pubmed-meshheading:9124296-Membrane Potentials,
pubmed-meshheading:9124296-Muscle, Smooth,
pubmed-meshheading:9124296-Sodium,
pubmed-meshheading:9124296-Ureter
|
pubmed:year |
1997
|
pubmed:articleTitle |
Roles of Ca2+ and Na+ in the inward current and action potentials of guinea pig ureteral myocytes.
|
pubmed:affiliation |
Department of Pharmacology, State University of New York Health Science Center at Brooklyn, 11203, USA.
|
pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
|