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KMID : 0438219790160030435
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Korea University Medical Journal
1979 Volume.16 No. 3 p.435 ~ p.441
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Effect of Cholera enterotoxin on Chronotropism in Isolated Rabbit Sinoatrial Node
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Abstract
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Many studies have accumulated that the involvement of cyclic adenosine 3´ : 5´-monophosphate (cyclic AMP) as a mediator of the action of cholera enterotoxin was clearly established.
Schafer reported that crude toxin promotes the elevation of tissue cyclic AMP levels in dog intestinal mucosa concomitant with the onset of its action.
The author, therefore, attempted to investigate the effect of cholera enterotoxin on the cyclic AMP system and on the pacemaker rate in the S-A node.
The results obtained were summarized as follows;
1. Cholera enterotoxin produced a time and dose-dependent increase in pacemaker rate and in cyclic AMP levels.
2. Cholera enterotoxin caused increase in adenylate cyclase activity and in the sensitivity of cyclic AMP levels to norepinephrine.
3. Cholera enterotoxin had a linear relation between pacemaker rate and cyclic AMP contents.
4. Norepinephrine also had a linear relation between pacemaker rate and cyclic AMP contents. But the angle of norepinephrine-line was steeper than the angle of cholera enterotoxin-line.
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