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PMID: 7099919 Published · ppublish English Journal Article Research Support, Non-U.S. Gov't

Intracellular calcium and sodium activity in sheep heart Purkinje fibres. Effect of changes of external sodium and intracellular pH.

Pflugers Archiv : European journal of physiology ·Vol. 393 ·No. 2 ·1982-04-00 ·Pages 171-8

Bers DM, Ellis D

Abstract

Intracellular Ca, Na and H selective microelectrodes were used to study the effects of reduction of the extracellular Na concentration, [Na]0, on the free intracellular Ca concentration, [Ca]i, Na activity, (aiNa), and intracellular pH (pHi) in sheep heart Purkinje fibres. 1. Reduction of [Na]0 from 140 mM to 14 mM produced a decrease of aiNa, and increase of free [Ca]i, and normally an increase of resting tension. 2. Inhibition of the Na-K pump by 10(-5) M acetyl-strophanthidin produced a slow rise of [Ca]i and resting tension. 3. The magnitude of the increase of free [Ca]i (and tension) produced by [Na]0 reduction was greatly enhanced when the Na-K pump is inhibited by either acetylstrophanthidin or K-free solutions. 4. We suggest that this enhanced rise of free [Ca]i in the presence of Na-K pump inhibition is due to Ca loading of intracellular Ca buffering systems during the pump inhibition. 5. Addition of NH4Cl produced a transient decrease of free [Ca]i that accompanied an alkaline change in pHi. Removal of NH4Cl (which produced a transient intracellular acidification) produced a transient increase of free [Ca]i. We conclude that a close relationship exists between the control of free [Ca]i and pHi which may be due to competition at, or common use of, intracellular buffering systems.

MeSH Terms
Animals Caffeine/pharmacology Calcium/metabolism Heart Conduction System/metabolism Hydrogen-Ion Concentration In Vitro Techniques Potassium/metabolism Purkinje Fibers/metabolism Sheep Sodium/metabolism
Chemicals
Caffeine Sodium Potassium Calcium
Authors & Affiliations
2 authors, click to expand affiliations / ORCID
Bers D M
Ellis D
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39 references, click to expand
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Article Info
Journal
Pflugers Archiv : European journal of physiology
Abbr.
Pflugers Arch
ISSN
0031-6768
DOI
10.1007/BF00582941
Published
1982-04-00
Pages
171-8
Language
English
Region
Germany
NLM ID
0154720
Subset
IM
External Links
PubMed source DOI: 10.1007/BF00582941 View journal details
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