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Different sensitivity of sinus node and atrioventricular node to adenosine triphosphate Takeshi Shirayama 1 , Daisuke Inoue 1 , Itsuki Omori 1 , Tetsuya Tatsumi 1 , Hirotaka Tatsukawa 1 , Jun Asayama 1 , Hiroshi Katsume 1 , Masao Nakagawa 1 , Yasuhiro Tsuji 2 1The Second Department of Medicine, Kyoto Prefectural University of Medicine 2The Third Department of Medicine, Matsushita Memorial Hospital Keyword: アデノシン三リン酸(ATP) , 洞結節(sinus node) , 房室結節(AV node) pp.59-63
Published Date 1990/1/15
DOI https://doi.org/10.11477/mf.1404900083
  • Abstract
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We showed that higher concentration of adenosine 5'-triphosphate (ATP) was required to prolong the spontaneous cycle length of the sinus node (SN) than that required to prolong the spontaneous cycle length of the atrioventricular node (AVN).

Spontaneously beating preparations of SN and AVN of rabbit (n=8) were superfused with Tyrode solution containing 10-8-10-3M ATP, and action potential was recorded. The negative chronotropic action of ATP was dependent on the concentration. The required concentration of ATP to prolong spontaneous cycle length significantly (p<0. 01) was 10-5M in SN and 10-6M in AVN, respectively. At concentrations higher than 10-6M, the degree of prolongation was greater in AVN than in SN (p<0.01). 10-7M dipyridamole enhanced this effect of ATP, while 10-4M theophylline reduced it.

Action potential duration of 50% repolarization was not changed significantly in either SN or AVN at concentrations up to 10-3M. Maximum diastolic potential (MDP) was hyperpolarized from 10-8M to 10-4M. Hyperpolarization of MDP induced by ATP was greater in AVN than in SN but it was not statistically significant. MDP was depolarized by 10-3M ATP in both SN and AVN. The maximum velocity of depolarization was slightly larger in both SN and AVN as the concentration of ATP was increased in the perfusate. However, it was not statistically significant. 10-3M ATP decreased the maximum velocity of depolarization.

Through these experiments, it is concluded that the negative chronotropic effect of ATP is consider-ed to be developed via the adenosine receptor, and this effect is more potent in AVN than in SN.=


Copyright © 1990, Igaku-Shoin Ltd. All rights reserved.

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電子版ISSN 1882-1200 印刷版ISSN 0452-3458 医学書院

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