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KMID : 0377519870120020195
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Chung-Ang Journal of Medicine
1987 Volume.12 No. 2 p.195 ~ p.203
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Effects of Higenamine on the Electrical Properites of the Rabbit Sinoatrial Node
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Abstract
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The rabbit sinoatrial rode was cut into small pieces which were 0. 5 X 0. 5 mm in sizes, electrically insulated and could be partitioned into central and peripheral areas.
Glass microelectrodes were impaled into both areas and transmembrane potentials were recorded in order to observe the changes in effects of higenamine on the both areas by the addition of TEA, Cs+ and Ba´,+ ,or pretreatment of propranolol.
1. Effects of higenamine were more prominent in high K+ concentration than those in the low K´ concentration.
2. TEA induced the decrease in the spontaneous firing rate and the prolongation in the action potential duration which could be reversed by higenamine.
3. There were prominent decrease of spontaneous firing rate and prolongation in the action potential duration in peripheral area with the increase of Cs+ concentration. Higenamine reversed the decrease of spontaneous firing rate in some degree.
4. There were significant decreases of spontaneous firing rate, amplitude of action potential and maximum diastolic potential by the Bat+ in peripheral area. Effects of Ba" were reversed by higenamine in central area.
5. The effects of higenamine were completely blocked by the pre-treatment of propranolol.
6. There was no effect of higenamine of the Na-K pump activities.
The above results could be interpreted as effects of higenamine were mediated by the change of calcium ion current rather than those of the potassium ion current in sinoatrial nodes.
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