KATP channels and adenosine are not necessary for coronary autoregulation

David W Stepp, Keith Kroll

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Autoregulation is defined as the intrin-sic ability of an organ to maintain constant flow in the face of changing perfusion pressure. The present study evaluated the role of several potential mediators of coronary autoregulation: interstitial adenosine, ATP-sensitive K+ (K-4TP) channels, and myocardial oxygen and carbon dioxide tensions as reflected by coronary venous oxygen and carbon dioxide tensions. The left main coronary artery was cannulated, and blood was perfused at controlled pressures in closed-chest dogs. Interstitial adenosine concentration was estimated from arterial and venous adenosine concentrations with a previously described mathematical model. Autoregulation of coronary blood flow was observed between 100 and 60 mmHg. Glibenclamide, an inhibitor of K-4TP channels, reduced coronary blood flow by 19% at each perfusion pressure, but autoregulation was preserved. After stepwise reductions in coronary pressure to values ä70 mmHg, adenosine concentrations did not increase above basal levels. Adenosine concentration was elevated at 60 mmHg, suggesting a role for adenosine at the limit of coronary autoregulation. Adenosine is not required because glibenclamide, an inhibitor of adenosinemediated vasodilation, did not reduce autoregulation or increase adenosine concentration. Coronary venous oxygen and carbon dioxide tensions were little changed during autoregulation before the inhibition of K-4TP channels and adenosine vasodilation with glibenclamide. However, coronary venous carbon dioxide tension rose progressively with decreasing coronary pressure after glibenclamide. The increase in carbon dioxide indirectly suggests that carbon dioxide-mediated vasodilation compensated for the loss of KJTP-channel function. In summary, neither K-4TP channels nor adenosine is necessary to maintain coronary flow in the autoregulatory range of coronary arterial pressure from 100 to 60 mmHg.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume42
Issue number3
StatePublished - Dec 1 1997
Externally publishedYes

Fingerprint

KATP Channels
Adenosine
Homeostasis
Carbon Dioxide
Glyburide
Pressure
Vasodilation
Oxygen
Perfusion
Coronary Vessels
Arterial Pressure
Theoretical Models
Thorax
Adenosine Triphosphate
Dogs

Keywords

  • Adenosine 5'-triphosphate-sensitive channels
  • Canine; model
  • Carbon dioxide
  • Glibenclamide
  • Oxygen
  • Perfusion pressure

ASJC Scopus subject areas

  • Physiology

Cite this

KATP channels and adenosine are not necessary for coronary autoregulation. / Stepp, David W; Kroll, Keith.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 42, No. 3, 01.12.1997.

Research output: Contribution to journalArticle

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AB - Autoregulation is defined as the intrin-sic ability of an organ to maintain constant flow in the face of changing perfusion pressure. The present study evaluated the role of several potential mediators of coronary autoregulation: interstitial adenosine, ATP-sensitive K+ (K-4TP) channels, and myocardial oxygen and carbon dioxide tensions as reflected by coronary venous oxygen and carbon dioxide tensions. The left main coronary artery was cannulated, and blood was perfused at controlled pressures in closed-chest dogs. Interstitial adenosine concentration was estimated from arterial and venous adenosine concentrations with a previously described mathematical model. Autoregulation of coronary blood flow was observed between 100 and 60 mmHg. Glibenclamide, an inhibitor of K-4TP channels, reduced coronary blood flow by 19% at each perfusion pressure, but autoregulation was preserved. After stepwise reductions in coronary pressure to values ä70 mmHg, adenosine concentrations did not increase above basal levels. Adenosine concentration was elevated at 60 mmHg, suggesting a role for adenosine at the limit of coronary autoregulation. Adenosine is not required because glibenclamide, an inhibitor of adenosinemediated vasodilation, did not reduce autoregulation or increase adenosine concentration. Coronary venous oxygen and carbon dioxide tensions were little changed during autoregulation before the inhibition of K-4TP channels and adenosine vasodilation with glibenclamide. However, coronary venous carbon dioxide tension rose progressively with decreasing coronary pressure after glibenclamide. The increase in carbon dioxide indirectly suggests that carbon dioxide-mediated vasodilation compensated for the loss of KJTP-channel function. In summary, neither K-4TP channels nor adenosine is necessary to maintain coronary flow in the autoregulatory range of coronary arterial pressure from 100 to 60 mmHg.

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