Effect of selective inhibition of potassium channels on vasorelaxing response to cromakalim, nitroglycerin and nitric oxide of canine coronary arteries

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Abstract

A comparative study was performed on the sensitivity of in-vitro vasorelaxation by nitroglycerin and cromakalim to block glibenclamide, a blocker of ATP-sensitive potassium channels, and iberiotoxin, a selective inhibitor of large-conductance calcium-activated potassium channels. In isolated canine coronary arteries preconstricted with 25 M prostaglandin F(2α), nitroglycerin (0.005-1 .8 μM) and cromakalim (0.15-9.6 μM) produced dose-dependent vasodilations. Glibenclamide (30 μM) had no significant effect on relaxation of the dose-response curve to nitroglycerin and almost completely abolished the relaxation by cromakalim, a known opener of ATP-sensitive potassium channels. Iberiotoxin (90 nM) decreased the maximal response to nitroglycerin and had no effect on the vasodilation induced by cromakalim. The effect of iberiotoxin on the vasorelaxing action of nitric oxide, the active metabolite of nitroglycerin, was also examined. In a low potassium chloride (14.4-20.4 mM) medium, as a contractile stimulus, iberiotoxin inhibited relaxations by exogenous nitric oxide (100-200 nM). Enhancement of potassium concentrations to 35.4-40.4 mM significantly decreased relaxation by nitric oxide and under these conditions the inhibitory action of iberiotoxin disappeared. The present study demonstrated that in canine coronary arteries, the functional role of two potassium channels can be separated by pharmacological means. Nitroglycerin-induced vasorelaxation may be mediated, at least in part, by its enzymatic breakdown product, nitric oxide that activates large-conductance calcium-activated potassium channels.

Original languageEnglish
Pages (from-to)921-925
Number of pages5
JournalJournal of Pharmacy and Pharmacology
Volume47
Issue number11
Publication statusPublished - 1995

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Cromakalim
Potassium Channels
Nitroglycerin
Canidae
Coronary Vessels
Nitric Oxide
Vasodilation
Large-Conductance Calcium-Activated Potassium Channels
KATP Channels
Glyburide
Potassium Chloride
Potassium
iberiotoxin
Pharmacology

ASJC Scopus subject areas

  • Pharmacology
  • Pharmaceutical Science

Cite this

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title = "Effect of selective inhibition of potassium channels on vasorelaxing response to cromakalim, nitroglycerin and nitric oxide of canine coronary arteries",
abstract = "A comparative study was performed on the sensitivity of in-vitro vasorelaxation by nitroglycerin and cromakalim to block glibenclamide, a blocker of ATP-sensitive potassium channels, and iberiotoxin, a selective inhibitor of large-conductance calcium-activated potassium channels. In isolated canine coronary arteries preconstricted with 25 M prostaglandin F(2α), nitroglycerin (0.005-1 .8 μM) and cromakalim (0.15-9.6 μM) produced dose-dependent vasodilations. Glibenclamide (30 μM) had no significant effect on relaxation of the dose-response curve to nitroglycerin and almost completely abolished the relaxation by cromakalim, a known opener of ATP-sensitive potassium channels. Iberiotoxin (90 nM) decreased the maximal response to nitroglycerin and had no effect on the vasodilation induced by cromakalim. The effect of iberiotoxin on the vasorelaxing action of nitric oxide, the active metabolite of nitroglycerin, was also examined. In a low potassium chloride (14.4-20.4 mM) medium, as a contractile stimulus, iberiotoxin inhibited relaxations by exogenous nitric oxide (100-200 nM). Enhancement of potassium concentrations to 35.4-40.4 mM significantly decreased relaxation by nitric oxide and under these conditions the inhibitory action of iberiotoxin disappeared. The present study demonstrated that in canine coronary arteries, the functional role of two potassium channels can be separated by pharmacological means. Nitroglycerin-induced vasorelaxation may be mediated, at least in part, by its enzymatic breakdown product, nitric oxide that activates large-conductance calcium-activated potassium channels.",
author = "J. Pataricza and G. T{\'o}th and B. Penke and J. Hohn and J. Papp",
year = "1995",
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T1 - Effect of selective inhibition of potassium channels on vasorelaxing response to cromakalim, nitroglycerin and nitric oxide of canine coronary arteries

AU - Pataricza, J.

AU - Tóth, G.

AU - Penke, B.

AU - Hohn, J.

AU - Papp, J.

PY - 1995

Y1 - 1995

N2 - A comparative study was performed on the sensitivity of in-vitro vasorelaxation by nitroglycerin and cromakalim to block glibenclamide, a blocker of ATP-sensitive potassium channels, and iberiotoxin, a selective inhibitor of large-conductance calcium-activated potassium channels. In isolated canine coronary arteries preconstricted with 25 M prostaglandin F(2α), nitroglycerin (0.005-1 .8 μM) and cromakalim (0.15-9.6 μM) produced dose-dependent vasodilations. Glibenclamide (30 μM) had no significant effect on relaxation of the dose-response curve to nitroglycerin and almost completely abolished the relaxation by cromakalim, a known opener of ATP-sensitive potassium channels. Iberiotoxin (90 nM) decreased the maximal response to nitroglycerin and had no effect on the vasodilation induced by cromakalim. The effect of iberiotoxin on the vasorelaxing action of nitric oxide, the active metabolite of nitroglycerin, was also examined. In a low potassium chloride (14.4-20.4 mM) medium, as a contractile stimulus, iberiotoxin inhibited relaxations by exogenous nitric oxide (100-200 nM). Enhancement of potassium concentrations to 35.4-40.4 mM significantly decreased relaxation by nitric oxide and under these conditions the inhibitory action of iberiotoxin disappeared. The present study demonstrated that in canine coronary arteries, the functional role of two potassium channels can be separated by pharmacological means. Nitroglycerin-induced vasorelaxation may be mediated, at least in part, by its enzymatic breakdown product, nitric oxide that activates large-conductance calcium-activated potassium channels.

AB - A comparative study was performed on the sensitivity of in-vitro vasorelaxation by nitroglycerin and cromakalim to block glibenclamide, a blocker of ATP-sensitive potassium channels, and iberiotoxin, a selective inhibitor of large-conductance calcium-activated potassium channels. In isolated canine coronary arteries preconstricted with 25 M prostaglandin F(2α), nitroglycerin (0.005-1 .8 μM) and cromakalim (0.15-9.6 μM) produced dose-dependent vasodilations. Glibenclamide (30 μM) had no significant effect on relaxation of the dose-response curve to nitroglycerin and almost completely abolished the relaxation by cromakalim, a known opener of ATP-sensitive potassium channels. Iberiotoxin (90 nM) decreased the maximal response to nitroglycerin and had no effect on the vasodilation induced by cromakalim. The effect of iberiotoxin on the vasorelaxing action of nitric oxide, the active metabolite of nitroglycerin, was also examined. In a low potassium chloride (14.4-20.4 mM) medium, as a contractile stimulus, iberiotoxin inhibited relaxations by exogenous nitric oxide (100-200 nM). Enhancement of potassium concentrations to 35.4-40.4 mM significantly decreased relaxation by nitric oxide and under these conditions the inhibitory action of iberiotoxin disappeared. The present study demonstrated that in canine coronary arteries, the functional role of two potassium channels can be separated by pharmacological means. Nitroglycerin-induced vasorelaxation may be mediated, at least in part, by its enzymatic breakdown product, nitric oxide that activates large-conductance calcium-activated potassium channels.

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