Moderate elevation of extracellular K+ concentration induces vasorelaxation in isolated rat, rabbit and human cerebral arteries: Role of Na pump and Ba-sensitive process.
- Author:
Dong Ho KIM
1
;
Sung Joon KIM
;
Sang Jin LEE
;
Sung Jin PARK
;
Ki Whan KIM
Author Information
1. Department of Physiology and Biophysics, Seoul National University College of Medicine, 28 Yongon-Dong, Chongno-Gu, Seoul 110-799, Korea.
- Publication Type:Original Article
- Keywords:
Cerebral artery;
Vasorelaxation;
Myograph;
Potassium;
Ouabain;
Barium
- MeSH:
Animals;
Barium;
Blood Vessels;
Cerebral Arteries*;
Dinoprost;
Histamine;
Humans*;
Middle Cerebral Artery;
Ouabain;
Potassium;
Rabbits;
Rats*;
Relaxation;
Sodium-Potassium-Exchanging ATPase;
Vasodilation*
- From:The Korean Journal of Physiology and Pharmacology
1998;2(6):705-714
- CountryRepublic of Korea
- Language:English
-
Abstract:
Cerebral blood vessels relax when extracellular K+ concentrations ((K+))e are elevated moderately (2~15 mM, K+-induced vasorelaxation). We have therefore studied the underlying mechanism for this K+-induced vasorelaxation in the isolated middle cerebral arteries (MCAs). The effects of ouabain and Ba2+ on K+-induced vasorelaxation were examined to determine the role of sodium pump and/or Ba-sensitive process (possibly, inward rectifier K current) in the mechanism. Mulvany myograph was used to study 24 rats, 18 rabbits, and 10 humans MCAs (216+/-3 mum, 347+/-7 mum, and 597+/-39 mum in diameter when stretched to a tension equivalent to 55 mmHg). High K+ (125 mM) and PGF2alpha (1~10 muM) induced concentration-dependent contractions in all 3 species, while histamine (10~50 muM) evoked contraction only in the rabbits and induced relaxation in the rats and humans. Addition of K+ (2~10 mM) to the control solution induced vasorelaxations. These effects were inhibited by the pretreatment with both ouabain (10 muM) and Ba2+ (0.1~0.3 mM) in the rat, but only with ouabain (10 muM) in the rabbit and human. These results suggest that K+-induced vasorelaxation occurs via the stimulation of electrogenic Na pump in the rabbit and human MCAs, while in the rat MCAs via the activation of both Na pump and Ba-sensitive process.
