Role of potassium channels in cerebral blood vessels.
BACKGROUND
Hyperpolarization of vascular muscle in response to activation of potassium channels is a major mechanism of vasodilatation. In cerebral blood vessels, four different potassium channels have been described: ATP-sensitive potassium channels, calcium-activated potassium channels, delayed rectifier potassium channels, and inward rectifier potassium channels.


RESULTS
Activation of ATP-sensitive and calcium activated potassium channels appears to play a major role in relaxation of cerebral arteries and arterioles in response to diverse stimuli, including receptor-mediated agonists, intracellular second messengers, and hypoxia. Both calcium-activated and delayed rectifier potassium channels may contribute to a negative feedback system that regulates tone in large cerebral arteries. The influence of ATP-sensitive and calcium-activated potassium channels is altered in disease states such as hypertension, diabetes, and atherosclerosis.


CONCLUSIONS
Activation of potassium channels is a major mechanism of cerebral vasodilatation. Alteration of activity of potassium channels and impairment of vasodilatation may contribute to the development or maintenance of cerebral ischemia or vasospasm.
Kitazono
T
T
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242, USA.
Faraci
F M
FM
Taguchi
H
H
Heistad
D D
DD
D000255:Adenosine Triphosphate / Q000502:physiology; D001161:Arteriosclerosis / Q000503:physiopathology; D002118:Calcium / Q000502:physiology; D002536:Cerebral Arteries / Q000502:physiology*; D002550:Cerebral Veins / Q000502:physiology*; D003920:Diabetes Mellitus / Q000503:physiopathology; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D015221:Potassium Channels / Q000145:classification / Q000502:physiology*; D015290:Second Messenger Systems; D014664:Vasodilation
D015221:Potassium Channels; D000255:Adenosine Triphosphate; D002118:Calcium