Regulation of membrane potential and diameter by voltage-dependent K+ channels in rabbit myogenic cerebral arteries

H. J. Knot, M. T. Nelson

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The hypothesis that voltage-dependent K+ channels are involved in the regulation of arterial smooth muscle membrane potential and blood vessel diameter was tested by examining the effects of inhibitors [4-aminopyridine (4-AP) and 3,4-diaminopyridine (3,4-DAP)] of voltage-dependent K+ channels on the membrane potential and diameter of pressurized small (100- to 300-μm diam) cerebral arteries from rabbit. In response to graded elevations in transmural pressure (20-100 mmHg), the membrane potential of smooth muscle cells in these arteries depolarized and the arteries constricted. 4-AP (1 mM) and 3,4-DAP (1 mM) depolarized cerebral arteries by 19 and 21 mV, respectively, when they were subjected to a transmural pressure of 80 mmHg. 3-Aminopyridine (3-AP, 1 mM), which is a relatively poor inhibitor of voltage-dependent K+ channels, depolarized smooth muscle cells in the arteries by 1 mV. 4-AP and 3,4-DAP constricted pressurized (to 80 mmHg) cerebral arteries. 3-AP had little effect on arterial diameter. 4-AP increased the arterial constriction to transmural pressure over a wide range of pressures (40-90 mmHg). The effects of 4-AP and 3,4-DAP on membrane potential and diameter were not prevented by inhibitors of calcium channels, calcium-activated K+ channels, ATP-sensitive K+ channels, inward rectifier K+ channels, blockers of adrenergic, serotonergic, muscarinic, and histaminergic receptors, or removal of the endothelium. These results suggest that voltage-dependent K+ channels are involved in the regulation of membrane potential and response of small cerebral arteries to changes in intravascular pressure.
    Original languageEnglish
    Pages (from-to)H348-H355
    JournalAmerican Journal of Physiology: Heart and Circulatory Physiology
    Volume269
    Issue number1
    Publication statusPublished - 1995

    Keywords

    • 3,4-diaminopyridine
    • 4-aminopyridine
    • calcium channels
    • calcium-activated potassium channels
    • delayed rectifier
    • dihydropyridine
    • diltiazem
    • iberiotoxin
    • nisoldipine
    • vascular smooth muscle
    • vasospasm

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