Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 393 (2), 171-8

Intracellular Calcium and Sodium Activity in Sheep Heart Purkinje Fibres. Effect of Changes of External Sodium and Intracellular pH

Intracellular Calcium and Sodium Activity in Sheep Heart Purkinje Fibres. Effect of Changes of External Sodium and Intracellular pH

D M Bers et al. Pflugers Arch.

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.

Similar articles

See all similar articles

Cited by 81 articles

See all "Cited by" articles

References

    1. J Physiol. 1977 Dec;273(1):295-316 - PubMed
    1. J Physiol. 1980 Jul;304:471-88 - PubMed
    1. J Membr Biol. 1981;61(2):115-25 - PubMed
    1. Science. 1980 Jun 27;208(4451):1461-4 - PubMed
    1. Pharmacol Rev. 1971 Sep;23(3):193-261 - PubMed

Publication types

Feedback