Role of Ca2+-activated K+ channels on adrenergic responses of human saphenous vein.
Am J Hypertens
; 20(1): 78-82, 2007 Jan.
Article
in En
| MEDLINE
| ID: mdl-17198916
ABSTRACT
BACKGROUND:
We studied the participation of K(+) channels on the adrenergic responses in human saphenous veins as well as the intervention of dihydropyridine-sensitive Ca(2+) channels on modulation of adrenergic responses by K(+) channels blockade.METHODS:
Saphenous vein rings were obtained from 40 patients undergoing coronary artery bypass surgery. The vein rings were suspended in organ bath chambers for isometric recording of tension.RESULTS:
Iberiotoxin (10(-7) mol/L), an inhibitor of large conductance Ca(2+)-activated K(+) channels, and charybdotoxin (10(-7) mol/L), an inhibitor of both large and intermediate conductance Ca(2+)-activated K(+) channels, enhanced the contractions elicited by electrical field stimulation and produced a leftward shift of the concentration-response curve to norepinephrine. In contrast, the inhibitor of small conductance Ca(2+)-activated K(+) channels apamin (10(-6) mol/L) did not modify the contractile response to electrical field stimulation or norepinephrine. In the presence of the dihydropyridine Ca(2+)-channel blocker nifedipine (10(-6) mol/L), iberiotoxin and charybdotoxin failed to enhance the contractile responses to electrical field stimulation and norepinephrine.CONCLUSIONS:
The results suggest that large conductance Ca(2+)-activated K(+) channels are activated by stimulation with norepinephrine to counteract the adrenergic-induced contractions of human saphenous vein. Thus, inhibition of these channels increases significantly the contraction, an effect that appears to be mediated by an increase in Ca(2+) entry through L-type voltage-dependent Ca(2+) channels.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Saphenous Vein
/
Vasoconstriction
/
Norepinephrine
/
Potassium Channels, Calcium-Activated
/
Muscle, Smooth, Vascular
Limits:
Female
/
Humans
/
Male
/
Middle aged
Language:
En
Journal:
Am J Hypertens
Journal subject:
ANGIOLOGIA
Year:
2007
Document type:
Article
Affiliation country:
Spain
Country of publication:
EEUU
/
ESTADOS UNIDOS
/
ESTADOS UNIDOS DA AMERICA
/
EUA
/
UNITED STATES
/
UNITED STATES OF AMERICA
/
US
/
USA