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KMID : 0377519850100010035
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Chung-Ang Journal of Medicine
1985 Volume.10 No. 1 p.35 ~ p.42
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Effect of Calcium on the Automaticity by Locations Rabbit S-A Node
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Abstract
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Effects´ of external Ca 21 on the spontaneous firing rates of the isolated rabbit atria, the whole SA node, and the small strips of SA node at constant temperature were observed and analyzed by recording the transmembrane action potentials. The results were as follows:
1. It has been shown that a positive chronotropic effect in the isolated atrium and whole SA node has.. appeared at elevated Cal+ concentration.
2. On the contrary, negative chronotropic effect of Ca 2+ were observed in a small strip of SA node.
3. The each small strip of SA node could be divided into two kinds of cells, i.e., peripheral pacemaker
cells and central pacemaker cells. In central pacemaker cells, Ca´ has shown positive chronotropy´
but opposite effect was observed in peripheral pacemaker cells.
4. The central pacemaker cells of the small strip of SA node could be divided into two groups with configuration and parameters of action potentials. The two groups showed different degree of positive chronotropic; effect respectively with elevated Cal+ concentration.
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