Blockade of ATP-sensitive potassium channels prevents the attenuation of the exercise pressor reflex by tempol in rats with ligated femoral arteries

Katsuya Yamauchi, Audrey J. Stone, Sean D. Stocker, Marc P. Kaufman

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

We reported previously that tempol attenuated the exercise pressor and muscle mechanoreceptor reflexes in rats whose femoral arteries were ligated, whereas tempol did not attenuate these reflexes in rats whose femoral arteries were freely perfused. Although the mechanism whereby tempol attenuated these reflexes in rats whose femoral artery was ligated was independent of its ability to scavenge reactive oxygen species, its nature remains unclear. An alternative explanation for the tempol-induced attenuation of these reflexes involves ATP-sensitive potassium channels (K Atp) and calcium-activated potassium channels (BK Ca), both of which are opened by tempol. We tested the likelihood of this explanation by measuring the effects of either glibenclamide (0.1 mg/kg), which blocks K Atp channels, or iberiotoxin (20 or 40 (μg/kg), which blocks BK Ca channels, on the tempol-induced attenuation of the exercise pressor and muscle mechanoreceptor reflexes in decerebrated rats whose femoral arteries were ligated. We found that glibenclamide prevented the tempol-induced attenuation of both reflexes, whereas iberiotoxin did not. We also found that the amount of protein comprising the pore of the K Atp channel in the dorsal root ganglia innervating hindlimbs whose femoral artery was ligated was significantly greater than that in the dorsal root ganglia innervating hindlimbs whose femoral arteries were freely perfused. In contrast, the amounts of protein comprising the BK Ca channel in the dorsal root ganglia innervating the ligated and freely perfused hindlimbs were not different. We conclude that tempol attenuated both reflexes by opening K Atp channels, an effect that hyperpolarized muscle afferents stimulated by static contraction or tendon stretch.

Original languageEnglish (US)
Pages (from-to)332-340
Number of pages9
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume303
Issue number3
StatePublished - Aug 1 2012

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KATP Channels
Femoral Artery
Reflex
Spinal Ganglia
Hindlimb
Large-Conductance Calcium-Activated Potassium Channels
Mechanoreceptors
Glyburide
Muscles
Calcium-Activated Potassium Channels
Porins
Aptitude
tempol
Tendons
Reactive Oxygen Species

All Science Journal Classification (ASJC) codes

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

Cite this

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abstract = "We reported previously that tempol attenuated the exercise pressor and muscle mechanoreceptor reflexes in rats whose femoral arteries were ligated, whereas tempol did not attenuate these reflexes in rats whose femoral arteries were freely perfused. Although the mechanism whereby tempol attenuated these reflexes in rats whose femoral artery was ligated was independent of its ability to scavenge reactive oxygen species, its nature remains unclear. An alternative explanation for the tempol-induced attenuation of these reflexes involves ATP-sensitive potassium channels (K Atp) and calcium-activated potassium channels (BK Ca), both of which are opened by tempol. We tested the likelihood of this explanation by measuring the effects of either glibenclamide (0.1 mg/kg), which blocks K Atp channels, or iberiotoxin (20 or 40 (μg/kg), which blocks BK Ca channels, on the tempol-induced attenuation of the exercise pressor and muscle mechanoreceptor reflexes in decerebrated rats whose femoral arteries were ligated. We found that glibenclamide prevented the tempol-induced attenuation of both reflexes, whereas iberiotoxin did not. We also found that the amount of protein comprising the pore of the K Atp channel in the dorsal root ganglia innervating hindlimbs whose femoral artery was ligated was significantly greater than that in the dorsal root ganglia innervating hindlimbs whose femoral arteries were freely perfused. In contrast, the amounts of protein comprising the BK Ca channel in the dorsal root ganglia innervating the ligated and freely perfused hindlimbs were not different. We conclude that tempol attenuated both reflexes by opening K Atp channels, an effect that hyperpolarized muscle afferents stimulated by static contraction or tendon stretch.",
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Blockade of ATP-sensitive potassium channels prevents the attenuation of the exercise pressor reflex by tempol in rats with ligated femoral arteries. / Yamauchi, Katsuya; Stone, Audrey J.; Stocker, Sean D.; Kaufman, Marc P.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 303, No. 3, 01.08.2012, p. 332-340.

Research output: Contribution to journalArticle

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