Functional evidence for inward-rectifier potassium channels in rat cremaster muscle arterioles.
Moderate increases in extracellular K(+) produce vasodilation in fourth order cremasteric arterioles in the anesthetized rat. We studied the contribution of different subtypes of K(+) channels to this response. Cremaster muscle arteriolar diameters were observed during superfusion with buffer containing 5-30 mM K(+) in the absence (control) and presence of barium (Ba(2+), 50 microM), glibenclamide (GLIB, 1 microM), or iberiotoxin (IBTX, 100 nM) to block inward-rectifier, ATP-sensitive, or Ca(2+)-activated K(+) channels, respectively. Under control conditions, vessels dilated in response to 10-25 mM K(+) and constricted at higher concentrations. At 5 mM K(+), vessel diameters were significantly decreased by GLIB and Ba(2+), but not IBTX, suggesting that basal diameter was regulated by inward-rectifier and ATP-sensitive K(+) channels. In contrast, Ba(2+), but not GLIB or IBTX, prevented K(+)-induced dilation. The data indicate that the inward-rectifier K(+) channel (blocked by low concentrations of Ba(2+), but not GLIB or IBTX) was most likely responsible for the K(+)-induced arteriolar dilation.
Loeb
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Department of Anesthesia, University of Pennsylvania Health System, Philadelphia, Pennsylvania, 19104, USA.
Godény
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Longnecker
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D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000378:metabolism*; D001464:Barium / Q000494:pharmacology; D001794:Blood Pressure / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005905:Glyburide / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply*; D010455:Peptides / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology
D010455:Peptides; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D014665:Vasodilator Agents; D001464:Barium; D011189:Potassium Chloride; C064719:iberiotoxin; D000241:Adenosine; D011188:Potassium; D005905:Glyburide