Contribution of electromechanical coupling between KV and CaV1.2 channels to coronary dysfunction in obesity

Zachary C. Berwick, Gregory M. Dick, Heather A. O'Leary, Shawn B. Bender, Adam G. Goodwill, Steven P. Moberly, Meredith Kohr Owen, Steven Miller, Alexander Obukhov, Johnathan Tune

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Previous investigations indicate that diminished functional expression of voltage-dependent K+ (KV) channels impairs control of coronary blood flow in obesity/metabolic syndrome. The goal of this investigation was to test the hypothesis that KV channels are electromechanically coupled to CaV1.2 channels and that coronary microvascular dysfunction in obesity is related to subsequent increases in CaV1.2 channel activity. Initial studies revealed that inhibition of KV channels with 4-aminopyridine (4AP, 0.3 mM) increased intracellular [Ca2+], contracted isolated coronary arterioles and decreased coronary reactive hyperemia. These effects were reversed by blockade of CaV1.2 channels. Further studies in chronically instrumented Ossabaw swine showed that inhibition of CaV1.2 channels with nifedipine (10 μg/kg, iv) had no effect on coronary blood flow at rest or during exercise in lean swine. However, inhibition of CaV1.2 channels significantly increased coronary blood flow, conductance, and the balance between coronary flow and metabolism in obese swine (P < 0.05). These changes were associated with a ~50 % increase in inward CaV1.2 current and elevations in expression of the pore-forming subunit (α1c) of CaV1.2 channels in coronary smooth muscle cells from obese swine. Taken together, these findings indicate that electromechanical coupling between KV and CaV1.2 channels is involved in the regulation of coronary vasomotor tone and that increases in CaV1.2 channel activity contribute to coronary microvascular dysfunction in the setting of obesity.

Original languageEnglish
Article number370
JournalBasic Research in Cardiology
Volume108
Issue number5
DOIs
StatePublished - 2013

Fingerprint

Swine
Obesity
4-Aminopyridine
Hyperemia
Arterioles
Nifedipine
Smooth Muscle Myocytes

Keywords

  • Ca1.2 channels
  • Coronary
  • Exercise
  • Obesity
  • Swine

ASJC Scopus subject areas

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

Cite this

Contribution of electromechanical coupling between KV and CaV1.2 channels to coronary dysfunction in obesity. / Berwick, Zachary C.; Dick, Gregory M.; O'Leary, Heather A.; Bender, Shawn B.; Goodwill, Adam G.; Moberly, Steven P.; Owen, Meredith Kohr; Miller, Steven; Obukhov, Alexander; Tune, Johnathan.

In: Basic Research in Cardiology, Vol. 108, No. 5, 370, 2013.

Research output: Contribution to journalArticle

Berwick, Zachary C. ; Dick, Gregory M. ; O'Leary, Heather A. ; Bender, Shawn B. ; Goodwill, Adam G. ; Moberly, Steven P. ; Owen, Meredith Kohr ; Miller, Steven ; Obukhov, Alexander ; Tune, Johnathan. / Contribution of electromechanical coupling between KV and CaV1.2 channels to coronary dysfunction in obesity. In: Basic Research in Cardiology. 2013 ; Vol. 108, No. 5.
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abstract = "Previous investigations indicate that diminished functional expression of voltage-dependent K+ (KV) channels impairs control of coronary blood flow in obesity/metabolic syndrome. The goal of this investigation was to test the hypothesis that KV channels are electromechanically coupled to CaV1.2 channels and that coronary microvascular dysfunction in obesity is related to subsequent increases in CaV1.2 channel activity. Initial studies revealed that inhibition of KV channels with 4-aminopyridine (4AP, 0.3 mM) increased intracellular [Ca2+], contracted isolated coronary arterioles and decreased coronary reactive hyperemia. These effects were reversed by blockade of CaV1.2 channels. Further studies in chronically instrumented Ossabaw swine showed that inhibition of CaV1.2 channels with nifedipine (10 μg/kg, iv) had no effect on coronary blood flow at rest or during exercise in lean swine. However, inhibition of CaV1.2 channels significantly increased coronary blood flow, conductance, and the balance between coronary flow and metabolism in obese swine (P < 0.05). These changes were associated with a ~50 {\%} increase in inward CaV1.2 current and elevations in expression of the pore-forming subunit (α1c) of CaV1.2 channels in coronary smooth muscle cells from obese swine. Taken together, these findings indicate that electromechanical coupling between KV and CaV1.2 channels is involved in the regulation of coronary vasomotor tone and that increases in CaV1.2 channel activity contribute to coronary microvascular dysfunction in the setting of obesity.",
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