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Exercise training increases inwardly rectifying K+ current and augments K+-mediated vasodilation in deep femoral artery of rats.
MedLine Citation:
PMID:  21349874     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Aims: A moderate increase in extracellular [K(+)] ([K(+)](e)) induces relaxation of small arteries via activating inwardly rectifying K(+) current (I(Kir)). The K(+)-vasodilation is an important mechanism for exercise-induced hyperemia in skeletal muscle. We investigated whether I(Kir) and K(+)-vasodilation are enhanced in deep femoral arteries (DFA) from exercise-trained rats (ET-rats, treadmill-running: 20 min at 20 m/min, six days for two weeks). The effects of ET on K(+)-vasodilation and I(Kir) were also investigated in cerebral (CA) and mesenteric arteries. Methods and Results: The K(+)-vasodilation of DFA and the density of I(Kir) and voltage-gated K(+) current (I(Kv)) were increased in DFA myocytes of ET-rats. The myogenic tone of DFA was unchanged by exercise. Although similar functional up-regulations of I(Kir) and I(Kv) were observed in CA myocytes, the K(+)-vasodilation was not increased in CA of ET-rats. Interestingly, concomitant to the increases in I(Kir) and I(Kv), background Na(+) conductance was also increased in the CA myocytes. However, such an effect was not observed in DFA myocytes from ET-rats. Neither I(Kir) nor K(+)-vasodilation was observed in mesenteric arteries of ET-rats. Conclusion: The present study provides evidence to report that regular exercise up-regulates I(Kir) in DFA and CA myocytes. Although the increase in I(Kir) was similarly observed in two types of arteries, augmentation of K(+)-relaxation was observed only in DFA of ET-rats, possibly due to the increased Na(+) conductance in CA myocytes. The increases in I(Kir) and K(+)-vasodilation of the arteries of skeletal muscle suggest novel mechanisms of improved exercise hyperemia with physical training.
Authors:
Chun Zi Jin; Hyang Sun Kim; Eun Yeong Seo; Dong Hoon Shin; Kyung Sun Park; Yang-Sook Chun; Yin Hua Zhang; Sung Joon Kim
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-2-23
Journal Detail:
Title:  Cardiovascular research     Volume:  -     ISSN:  1755-3245     ISO Abbreviation:  -     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-2-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0077427     Medline TA:  Cardiovasc Res     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Physiology, Seoul National University College of Medicine, Seoul 110-799, Korea.
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