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Science 8 August 1980:
Vol. 209. no. 4457, pp. 699 - 701
DOI: 10.1126/science.7394527
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Articles

Science, Vol 209, Issue 4457, 699-701
Copyright © 1980 by American Association for the Advancement of Science

articles

Sodium-calcium exchange in rabbit heart muscle cells: direct measurement of sarcoplasmic Ca2+ activity

CO Lee, DY Uhm, and K Dresdner

Calcium ion-selective microelectrodes made with Simon's neutral carrier were used to measure simultaneously sarcoplasmic Ca2+ activity (aiCa) and resting tension (Tr) of rabbit ventricular muscle during reduction and restoration of external sodium ion concentration, [Na]0. Under the same experimental conditions the change in contractile tension (Ta) also measured. In resting muscle the aiCa was 38 +/- 17 nanomolar (mean +/- standard deviation; N = 10). The reduction of [Na]O from 153 to 20 millimolar led to about a threefold increase in aiCa with parallel increases in Tr and Ta. The time course of the change in aiCa was similar to that of the changes in Tr and Ta. The results are consistent with an important role of the sodium-calcium exchange system for regulating sarcoplasmic Ca2+ activity.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Optical measurements of extracellular calcium depletion during a single heartbeat.
L Cleemann, G Pizarro, and M Morad (1984)
Science 226, 174-177
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