Potassium channels and vascular reactivity in genetically hypertensive rats

Philip B. Furspan, R. Clinton Webb

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

In hypertension, membrane potassium permeability and vascular reactivity are increased. This study characterizes a potassium-selective channel and contractions to barium, a potassium channel inhibitor, in vascular smooth muscle (tail artery) from spontaneously hypertensive stroke-prone rats (SHRSP) and normotensive Wistar-Kyoto (WKY) rats. Smooth muscle cells were isolated by enzymatic digestion, and potassium channel activity was characterized by using patch-clamp technique (inside-out configuration). Isometric contractile activity was evaluated in helically cut arterial strips by using standard muscle bath methodology. In membrane patches, a voltage-gated, calcium-insensitive, potassium-selective channel of large conductance (200 picosiemens) was observed. The channel did not conduct sodium or rubidium. Barium (10−6to 10−4M) produced a dose-dependent blockade of channel activity. These channel characteristics did not differ in SHRSP and WKY rat cells. After treatment with 35 mM KCI, barium (10−5to 10−3M) caused greater contractions in SHRSP arteries compared with arteries in WKY rats. The contractions to barium were markedly attenuated in calcium-free solution, and nifedipine and verapamil abolished contractions induced by barium in depolarizing solution. We conclude that increased vascular reactivity to barium in SHRSP arteries Is not due to an alteration in the biophysical properties of the potassium channel studied.

Original languageEnglish (US)
Pages (from-to)687-691
Number of pages5
JournalHypertension
Volume15
Issue number6
DOIs
StatePublished - Jun 1990

Keywords

  • Barium
  • Potassium
  • Stroke-prone spontaneously hypertensive rats
  • Vascular smooth muscle

ASJC Scopus subject areas

  • Internal Medicine

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