Effect of isoprenaline, carbachol, and Cs+ on Na+ activity and pacemaker potential in rabbit SA node cells

1  Department of Life Science, Pohang University of Science and Technology, Pohang, Republic of Korea; and 2  University Laboratory of Physiology, Oxford University, Oxford OX1 3PT, United Kingdom Effects of isoprenaline, carbachol, and Cs + on intracellular Na + activity ( a i Na ) and spontaneous...

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Published in:American journal of physiology. Heart and circulatory physiology 1999-01, Vol.276 (1), p.H205-H214
Main Authors: Choi, Ho S, Wang, Dai Y, Noble, Denis, Lee, Chin O
Format: Article
Language:English
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Summary:1  Department of Life Science, Pohang University of Science and Technology, Pohang, Republic of Korea; and 2  University Laboratory of Physiology, Oxford University, Oxford OX1 3PT, United Kingdom Effects of isoprenaline, carbachol, and Cs + on intracellular Na + activity ( a i Na ) and spontaneous action potentials were studied in multicellular and single cell preparations isolated from rabbit sinoatrial (SA) nodes. a i Na was measured with double-barreled Na + -selective microelectrodes and the fluorescent Na + -indicator sodium-binding benzofuran isophthalate (SBFI). In spontaneously beating cells, a i Na measured with Na + -selective microelectrodes and SBFI were 4.5 ± 1.2 mM (means ±   SD, n  = 21) in multicellular preparations and 4.0 ± 1.1 mM ( n   = 16) in single cells, respectively. Measurements of a i Na with microelectrodes showed that isoprenaline increased a i Na from 4.7 ± 1.2 to 5.5 ± 1.6 mM ( n  = 16,  P  
ISSN:0363-6135
1522-1539
DOI:10.1152/ajpheart.1999.276.1.h205