| Project/Area Number |
06670728
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Circulatory organs internal medicine
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| Research Institution | Nagasaki University |
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Principal Investigator |
YANO Katsusuke Nagasaki University 3rD Dept of Int Med Professor, 医学部, 教授 (50039864)
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| Co-Investigator(Kenkyū-buntansha) |
HAYANO Motonobu Nagasaki University 3rD Dept of Int Med Associate Professor, 医学部, 助教授 (60100864)
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| Project Period (FY) |
1994 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1996: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1994: ¥700,000 (Direct Cost: ¥700,000)
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| Keywords | atrial fibrillation / serum potassium / autonomic nerve / atrial extrastimulation |
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| Research Abstract |
In the present study we investigated electrophysiologic mechanism of atrial fibrillation in the dog with hypokalemia, with special reference to whether triggered activity plays important role in the genesis of atrial fibrillation in the presence of hypokalemia. Furthermore, influence of autonomic nerve on the occurrence of atrial fibrillation was also investigated. <Materials and Methods> Thirty mongrel dogs weighing 10-13kg were anesthetized with intravenous sodium pentobarbital (30mg/kg) and put on artificial respiration using room air. The chest was opened by a median sternotomy and heart was suspended in a pericardial cradle. Bipolar epicardial electrodes were positloned at multiple sites of the atrium. Furthermore, electrode for monophasic action potential (MAP) was positioned on the atrial wall. To produce hypokalemia ion exchange resin (5.0g/kg of polystirene sulfonic acid calcium) was infused into the colon in the dog.
To measure serum levels of potassium, sodium, chloride, calc
… More
ium, and magnesium, blood samples were taken before and sixty minutes after infusin of ion exchange resin. To stimulate autonomic nerves electrodes were positioned on the vagal nerve in the left neck and left stellate ganglion. Electrophysiologic study was performed before and 60 minutes after infusion of ion exchange resin and also performed under stimulation of autonomic nerves. <Results> Serum levels of potassium was signiflcantly reduced from 4.2+0.3mEq/L to 2.8+0.3mEq/L,but other electrolytes did not signiflcantly change. Incidence of electrically induced atrial fibrillation was increased in the presence of hypokalemia wit mild increase in intraatrial conduction delay and without signiflcant change in effective refractory period and these findings were increased by stimulations of both vagal nerve and stellate ganglion. Morphological changes of MAP suggesting existence of early after depolarization were observed after induction of hypokalemia and these changes were increased by stimulations of autonomic nerves. <Conclusion> In the presence of hypokalemia atrial fibrillation is readily induced and this inducibility is enhanced by increased tone of autonomic nerves. And triggered activity may play a rolein part in the occurrence of atrial fibrillation in this situation. Less
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