This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Milesi, V. Articles by de Gende, A. O. G. Search for Related Content PubMed PubMed Citation Articles by Milesi, V. Articles by Raingo, J. Articles by Rebolledo, A. Articles by de Gende, A. O. G. Social Bookmarking                         What's this?

Potassium Channels in Human Umbilical Artery Cells

Anatomía y Fisiología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115, La Plata (1900), Argentina; veronica{at}nahuel.biol.unlp.edu.ar

Jesica Raingo, BSc

Alejandro Rebolledo, PhD

Angela O. Grassi de Gende, MD

Anatomía y Fisiología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina

Objective: To identify K⁺ channels of smooth muscle of human umbilical artery using the patch-clamp technique and to study their effect on resting tone of umbilical artery rings.

Methods: Whole-cell and single-channel patch-clamp recordings in enzymatically isolated smooth muscle cells were made. Measurements of developed isometric force were performed on intact tissue.

Results: Delayed rectifier K⁺ channels (K_DR) and large-conductance Ca²⁺-activated K⁺ channels (BK_Ca) contribute to the whole-cell voltage-and time-dependent outward K⁺ current, as it was specifically inhibited by 5 mM 4-aminopyridine (4-AP; K_DR blocker) (92 ± 4% at 0 mV, n = 7), by 1 mM tetraethylammonium (TEA; BK_Ca blocker) (71 ± 4% at +60 mV, n = 4), and by 200 nM iberiotoxin (BK_Ca blocker) (64 ± 7% at +60 mV, n = 4). In outside-out patches, BK_Ca channels had single-channel conductance of 132 ± 4 pS (n = 24) in asymmetric K⁺ conditions and 216 ± 4 pS (n = 4) in a symmetric K⁺ gradient. The activity of the BK_Ca channels was significantly augmented by 1 µM Ca²⁺ in the inside-out configuration. 4-AP had no effect on resting tone of intact arterial rings. TEA produced contraction of arterial rings whereas phloretin, an activator of BK_Ca, relaxed them, which means that BK_Ca channels are functional in intact tissue and are involved in the maintenance of resting tone in this human vessel.

Conclusion: The identities of K⁺ channels in the human umbilical artery were shown using the patch-clamp technique, and the physiologic effect of K⁺ channels on resting tone was documented.

Key Words: BKCa currents • KDR currents • human umbilical artery • smooth muscle cells

Journal of the Society for Gynecologic Investigation, Vol. 10, No. 6, 339-346 (2003)
DOI: 10.1016/S1071-55760300117-5


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?