ATP-sensitive potassium channels in cultured arterial segments

Thomas Kleppisch, Barbara Winter, Mark T. Nelson

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Organ cultures of arteries have been used to study growth responses, proliferation, and contractility. However, the function of specific-ion channels in cultured arteries has not been investigated. ATP-sensitive K+ (K(ATP)) channels play an important role in the control of arterial tone. The goal of this study was to determine the functional state of KATP channels in arteries kept in culture. Segments from rabbit mesenteric arteries were cultured in for 2-7 days. To explore the properties of K(ATP) channels, the effects of K(ATP)channel modulators and other vasoactive substances on isometric force, density, and modulation of K(ATP) currents in single smooth muscle cells isolated from cultured vessels were examined. Isometric contractions were measured with a resistance-vessel myograph. Whole cell K(ATP) currents were recorded with the patch-clamp technique. Membrane capacitance and K(ATP)-current density in single smooth muscle cells from freshly dissected (control) and cultured arteries were not altered. At -60 mV, glibenclamide-sensitive currents in the presence of the K+-channel opener pinacidil were -4.7 ± 1.2, -4.7 ± 0.6, and -4.6 ± 0.7 pA]pF for control and 2- and 4-day arteries, respectively. Inhibitory modulation of K(ATP) currents in arterial smooth muscle also remained intact for 4 days in culture; the vasoconstrictor histamine (10 μM) reduced glibenclamide- sensitive currents in the presence of pinacidil by 61.2 ± 2.8, 42.4 ± 10.1, and 41.2 ± 6.1% for control and 2- and 4-day arteries, respectively. Pinacidil relaxed control and cultured arteries (1-7 days) in a dose- dependent manner. Half-maximal effective concentrations of pinacidil were 0.42, 0.24, 0.23, and 0.51 μM for control and 2-, 4-, and 7-day arteries, respectively, whereas maximal relaxations to pinacidil were 62.9, 47.5, 37.5, and 55.7% for control and 2-, 5-, and 7-day arteries, respectively. Histamine, norepinephrine, and serotonin constricted cultured arteries, although responses to histamine and norepinephrine diminished by 30-50% after 5 days in culture. The relaxant effect of acetylcholine was not maintained in cultured arteries. Sodium nitroprusside, however, effectively relaxed arteries cultured for 2-7 days. The data indicate that with the culture model described, K(ATP) channels in arterial smooth muscle remained functional and contractile responses in arterial segments were maintained for up to 7 days. These results suggest that this approach can be used to study either long- term regulation of K(ATP) channels or the role of this channel type in growth responses.

Original languageEnglish
Pages (from-to)H2462-H2468
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume271
Issue number6 40-6
DOIs
StatePublished - 1996

Keywords

  • adenosine 5'-triphosphate
  • arterial smooth muscle
  • glibenclamide
  • organ culture
  • pinacidil

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