Contribution of IKCa) channels to the control of coronary blood flow

Michelle M. Kurian, Zachary C. Berwick, Johnathan Tune

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The purpose of this investigation was to elucidate the contribution of intermediate conductance calcium-activated potassium channels (IKCa) to the regulation of coronary blood flow in vivo. We hypothesized that IKCa channels modulate coronary arteriolar resistance at rest and contribute to vasomotor responses to changes in coronary perfusion pressure and/or in response to cardiac ischemia. Experiments were conducted in open-chest anesthetized dogs in the absence and presence of IKCa channel inhibitor, TRAM-34 (1 mg/min, intracoronary), and the nitric oxide (NO) synthase inhibitor, NG-nitro-Larginine- methyl ester (L-NAME) (150 mg/min, intracoronary). We found that administration of the potent SKCa and IKCa channel agonist NS309 dose-dependently increased coronary blood flow and that inhibition of IKCa channels with TRAM- 34 attenuated this response by ~90%. The increase in coronary blood flow to NS309 was also decreased ~100% by the inhibition of NO production with L-NAME. Multiple linear regression analysis demonstrated that TRAM-34 diminished the autoregulatory capability of the coronary circulation at coronary pressures ranging from 60 to 120 mmHg. However, inhibition of IKCa channels did not affect coronary vasodilation in response to a transient 15 s coronary artery occlusion (i.e. reactive hyperemia). Our data reveal that IKCa channels are functionally expressed in the coronary circulation and that activation of these channels produces marked coronary vasodilation in vivo, primarily via increases in endothelial NO production. In addition, IKCa channels modestly contribute to changes in coronary vascular resistance in response to alterations in coronary perfusion pressure but do not contribute to the reactive hyperemic response following a brief coronary artery occlusion.

Original languageEnglish
Pages (from-to)621-627
Number of pages7
JournalExperimental Biology and Medicine
Volume236
Issue number5
DOIs
StatePublished - May 2011

Fingerprint

Coronary Circulation
Blood
Coronary Occlusion
NG-Nitroarginine Methyl Ester
Pressure
Vasodilation
Intermediate-Conductance Calcium-Activated Potassium Channels
Coronary Vessels
Nitric Oxide
Perfusion
Hyperemia
Linear regression
Regression analysis
Nitric Oxide Synthase
Vascular Resistance
Linear Models
Esters
Thorax
Ischemia
Chemical activation

Keywords

  • Coronary vasodilation
  • Ischemia
  • Pressure-flow autoregulation
  • Reactive hyperemia

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Contribution of IKCa) channels to the control of coronary blood flow. / Kurian, Michelle M.; Berwick, Zachary C.; Tune, Johnathan.

In: Experimental Biology and Medicine, Vol. 236, No. 5, 05.2011, p. 621-627.

Research output: Contribution to journalArticle

Kurian, Michelle M. ; Berwick, Zachary C. ; Tune, Johnathan. / Contribution of IKCa) channels to the control of coronary blood flow. In: Experimental Biology and Medicine. 2011 ; Vol. 236, No. 5. pp. 621-627.
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