Activation of ATP-sensitive potassium channels contributes to reactive hyperemia in humans

Peter F. Banitt, Paul Smits, Stephen B. Williams, Peter Ganz, Mark A. Creager

Research output: Contribution to journalArticlepeer-review

Abstract

Activation of ATP sensitive potassium (K(ATP)) channels present on vascular smooth muscle cells causes membrane hyperpolarization and vasodilation. The purpose of this study was to determine whether K(ATP) channels contribute to reactive hyperemia in humans. Accordingly, we studied the effect of tolbutamide, a K(ATP) 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 K(ATP) channels, adenosine (1.5-500 μg/min, n = 6) and acetylcholine (30 μg/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, K(ATP) channels contribute to vasodilation during reactive hyperemia in humans.

Original languageEnglish (US)
Pages (from-to)H1594-H1598
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume271
Issue number4 40-4
DOIs
StatePublished - Oct 1996
Externally publishedYes

Keywords

  • adenosine
  • ischemia
  • nitric oxide
  • regional blood flow
  • tolbutamide

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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