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, (aNa i), and intracellular pH (pHi) in sheep heart Purkinje fibres. 1. Reduction of [Na]0 from 140 mM to 14 mM produced a decrease of aNa i, and increase of free [Ca]i, and normally an increase of resting tension. 2. Inhibition of the Na-K pump by 10-5 M acetylstrophanthidin 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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 171-178 |
| Number of pages | 8 |
| Journal | Pflügers Archiv European Journal of Physiology |
| Volume | 393 |
| Issue number | 2 |
| DOIs | |
| State | Published - Apr 1982 |
| Externally published | Yes |
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Keywords
- Calcium
- Cardiac glycoside
- Heart
- pH
- Purkinje fibres
- Sodium
ASJC Scopus subject areas
- Physiology
Cite this
Intracellular calcium and sodium activity in sheep heart Purkinje fibres - Effect of changes of external sodium and intracellular pH. / Bers, Donald M; Ellis, David.
In: Pflügers Archiv European Journal of Physiology, Vol. 393, No. 2, 04.1982, p. 171-178.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Intracellular calcium and sodium activity in sheep heart Purkinje fibres - Effect of changes of external sodium and intracellular pH
AU - Bers, Donald M
AU - Ellis, David
PY - 1982/4
Y1 - 1982/4
N2 - 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, (aNa i), and intracellular pH (pHi) in sheep heart Purkinje fibres. 1. Reduction of [Na]0 from 140 mM to 14 mM produced a decrease of aNa i, and increase of free [Ca]i, and normally an increase of resting tension. 2. Inhibition of the Na-K pump by 10-5 M acetylstrophanthidin 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.
AB - 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, (aNa i), and intracellular pH (pHi) in sheep heart Purkinje fibres. 1. Reduction of [Na]0 from 140 mM to 14 mM produced a decrease of aNa i, and increase of free [Ca]i, and normally an increase of resting tension. 2. Inhibition of the Na-K pump by 10-5 M acetylstrophanthidin 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.
KW - Calcium
KW - Cardiac glycoside
KW - Heart
KW - pH
KW - Purkinje fibres
KW - Sodium
UR - http://www.scopus.com/inward/record.url?scp=0020054087&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0020054087&partnerID=8YFLogxK
U2 - 10.1007/BF00582941
DO - 10.1007/BF00582941
M3 - Article
VL - 393
SP - 171
EP - 178
JO - Pflugers Archiv European Journal of Physiology
JF - Pflugers Archiv European Journal of Physiology
SN - 0031-6768
IS - 2
ER -