Activation of ATP-sensitive potassium channels contributes to reactive hyperemia in humans.
Am J Physiol
; 271(4 Pt 2): H1594-8, 1996 Oct.
Article
en En
| MEDLINE
| ID: mdl-8897956
Activation of ATP-sensitive potassium (KATP) channels present on vascular smooth muscle cells causes membrane hyperpolarization and vasodilation. The purpose of this study was to determine whether KATP channels contribute to reactive hyperemia in humans. Accordingly, we studied the effect of tolbutamide, a KATP channel inhibitor, on reactive hyperemic forearm blood flow. Forearm blood flow was measured by venous occlusion plethysmography. Forearm ischemia was produced by inflating a sphygmomanometric cuff on the arm to suprasystolic pressures for 5 min. After cuff release, forearm blood flow was measured during the reactive hyperemic phase for 5 min. Tolbutamide (1 mM blood concentration, n = 6) did not affect basal (2.4 +/- 0.2 to 2.2 +/- 0.1 ml.100 ml-1.min-1) or peak reactive hyperemic forearm blood flow (21.9 +/- 3.8 to 22.6 +/- 2.9 ml.100 ml-1.min-1, each P = NS), but it significantly attenuated total hyperemic volume (12.6 +/- 1.7 vs. 9.2 +/- 1.8 ml/100 ml, P < 0.02). Vehicle (n = 6) did not affect basal flow, peak reactive hyperemic flow, or total hyperemia. To determine whether adenosine or endothelium-derived nitric oxide contribute to reactive hyperemia via KATP channels, adenosine (1.5-500 micro grams/min, n = 6) and acetylcholine (30 micrograms/min, n = 6) were infused before and during tolbutamide coinfusion. Tolbutamide did not significantly alter the forearm blood flow response to either adenosine or acetylcholine. In conclusion, KATP channels contribute to vasodilation during reactive hyperemia in humans.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Canales de Potasio
/
Adenosina Trifosfato
/
Hiperemia
Tipo de estudio:
Diagnostic_studies
Límite:
Adult
/
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Revista:
Am J Physiol
Año:
1996
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos