Membrane potential changes associated with calcium signals in human lymphocytes and rat mast cells

Ana G. Cabado, Sanda Despa, Manuel A. Botana, Mercedes R. Vieytes, Miguel González, Luis M. Botana

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Human lymphocytes and rat mast cells, two non-excitable cellular models, were used to investigate membrane potential changes accompanying Ca2+ signals. Cells were stimulated with agents known to induce both Ca2+ release from internal stores and influx of extracellular Ca2+, namely thapsigargin, ionomycin and compound 48/80. Thapsigargin and ionomycin were used to activate lymphocytes, while compound 48/80 was used to stimulate mast cells. Membrane potential changes and Ca2+ concentration were monitored with the fluorescent dyes bis-oxonol and fura-2, respectively. In lymphocytes, thapsigargin induced a hyperpolarization temporally correlated with the increase in intracellular Ca2+ concentration. This hyperpolarization is due to activation of a K+ conductance which consists of two phases, a first phase independent on external Ca2+ and a second one blocked in a Ca2+-free medium. Ionomycin induced a Ca2+-dependent depolarization attributed to a massive influx of external Ca2+. On the other hand, stimulation of mast cells with compound 48/80 produced a fast hyperpolarization and an increase in intracellular Ca2+ levels. Besides different time-courses, this hyperpolarization differs from that induced by thapsigargin in lymphocytes in two aspects., it is mainly due to a Cl-- entry current and exit of K+ and it is completely inhibited in the absence of extracellular Ca2+. Compound 48/80-induced histamine release is not related to membrane potential changes.

Original languageEnglish (US)
Pages (from-to)681-696
Number of pages16
JournalLife Sciences
Volume64
Issue number8
DOIs
StatePublished - Jan 15 1999
Externally publishedYes

Keywords

  • Calcium
  • Lymphocyte
  • Mast cell
  • Membrane potential
  • Oxonol
  • Potassium
  • Thapsigargin

ASJC Scopus subject areas

  • Pharmacology

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  • Cite this

    Cabado, A. G., Despa, S., Botana, M. A., Vieytes, M. R., González, M., & Botana, L. M. (1999). Membrane potential changes associated with calcium signals in human lymphocytes and rat mast cells. Life Sciences, 64(8), 681-696. https://doi.org/10.1016/S0024-3205(98)00610-9