Voltage-activated Na+ currents and their suppression by phorbol ester in clonal insulin-producing RINm5F cells

P. Rorsman, P. Arkhammar, P. O. Berggren

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

The whole-cell configuration of the patch-clamp technique was applied on the clonal insulin-producing cell line RINm5F. Thus attempts were made to characterize voltage-activated inward and outward membrane currents and to examine to what extent these were affected by both long-term and acute exposure to the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). Current responses to voltage-clamp steps up to -40 mV were small. A pulse to -28 mV evoked an inward current, and slowly activating outward currents developed at potentials above -20 mV. The inward current had a V-shaped current-voltage relationship, reaching a peak between -10 and 0 mV, whereas the outward current increased linearly at potentials beyond -20 mV. It was demonstrated that the inward currents are carried primarily by Ca2+ and Na+ and the outward current by K+. After long-term exposure to TPA, there was a suppression of Na+ current in one-third of the cells, whereas the Ca2+ and K+ currents were unaffected. Acute exposure to the phorbol ester increased the Ca2+ currents with little effect on the Na+ currents. The extent to which the differences in effects on membrane currents initiated by respective acute and long-term exposure to TPA may reflect two separate mechanisms of protein kinase C activation, the latter related to regulation of differentiation of the RINm5F cells, merits further investigation.

Original languageEnglish
JournalAmerican Journal of Physiology - Cell Physiology
Volume251
Issue number6
StatePublished - Dec 1 1986
Externally publishedYes

Fingerprint

Phorbol Esters
Tetradecanoylphorbol Acetate
Acetates
Clamping devices
Insulin
Electric potential
Membranes
Patch-Clamp Techniques
Protein Kinase C
Cell Differentiation
Chemical activation
Cells
Cell Line

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology

Cite this

Voltage-activated Na+ currents and their suppression by phorbol ester in clonal insulin-producing RINm5F cells. / Rorsman, P.; Arkhammar, P.; Berggren, P. O.

In: American Journal of Physiology - Cell Physiology, Vol. 251, No. 6, 01.12.1986.

Research output: Contribution to journalArticle

@article{d39cc14d9c7348668988752a285bd3ee,
title = "Voltage-activated Na+ currents and their suppression by phorbol ester in clonal insulin-producing RINm5F cells",
abstract = "The whole-cell configuration of the patch-clamp technique was applied on the clonal insulin-producing cell line RINm5F. Thus attempts were made to characterize voltage-activated inward and outward membrane currents and to examine to what extent these were affected by both long-term and acute exposure to the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). Current responses to voltage-clamp steps up to -40 mV were small. A pulse to -28 mV evoked an inward current, and slowly activating outward currents developed at potentials above -20 mV. The inward current had a V-shaped current-voltage relationship, reaching a peak between -10 and 0 mV, whereas the outward current increased linearly at potentials beyond -20 mV. It was demonstrated that the inward currents are carried primarily by Ca2+ and Na+ and the outward current by K+. After long-term exposure to TPA, there was a suppression of Na+ current in one-third of the cells, whereas the Ca2+ and K+ currents were unaffected. Acute exposure to the phorbol ester increased the Ca2+ currents with little effect on the Na+ currents. The extent to which the differences in effects on membrane currents initiated by respective acute and long-term exposure to TPA may reflect two separate mechanisms of protein kinase C activation, the latter related to regulation of differentiation of the RINm5F cells, merits further investigation.",
author = "P. Rorsman and P. Arkhammar and Berggren, {P. O.}",
year = "1986",
month = "12",
day = "1",
language = "English",
volume = "251",
journal = "American Journal of Physiology - Cell Physiology",
issn = "0363-6143",
publisher = "American Physiological Society",
number = "6",

}

TY - JOUR

T1 - Voltage-activated Na+ currents and their suppression by phorbol ester in clonal insulin-producing RINm5F cells

AU - Rorsman, P.

AU - Arkhammar, P.

AU - Berggren, P. O.

PY - 1986/12/1

Y1 - 1986/12/1

N2 - The whole-cell configuration of the patch-clamp technique was applied on the clonal insulin-producing cell line RINm5F. Thus attempts were made to characterize voltage-activated inward and outward membrane currents and to examine to what extent these were affected by both long-term and acute exposure to the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). Current responses to voltage-clamp steps up to -40 mV were small. A pulse to -28 mV evoked an inward current, and slowly activating outward currents developed at potentials above -20 mV. The inward current had a V-shaped current-voltage relationship, reaching a peak between -10 and 0 mV, whereas the outward current increased linearly at potentials beyond -20 mV. It was demonstrated that the inward currents are carried primarily by Ca2+ and Na+ and the outward current by K+. After long-term exposure to TPA, there was a suppression of Na+ current in one-third of the cells, whereas the Ca2+ and K+ currents were unaffected. Acute exposure to the phorbol ester increased the Ca2+ currents with little effect on the Na+ currents. The extent to which the differences in effects on membrane currents initiated by respective acute and long-term exposure to TPA may reflect two separate mechanisms of protein kinase C activation, the latter related to regulation of differentiation of the RINm5F cells, merits further investigation.

AB - The whole-cell configuration of the patch-clamp technique was applied on the clonal insulin-producing cell line RINm5F. Thus attempts were made to characterize voltage-activated inward and outward membrane currents and to examine to what extent these were affected by both long-term and acute exposure to the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). Current responses to voltage-clamp steps up to -40 mV were small. A pulse to -28 mV evoked an inward current, and slowly activating outward currents developed at potentials above -20 mV. The inward current had a V-shaped current-voltage relationship, reaching a peak between -10 and 0 mV, whereas the outward current increased linearly at potentials beyond -20 mV. It was demonstrated that the inward currents are carried primarily by Ca2+ and Na+ and the outward current by K+. After long-term exposure to TPA, there was a suppression of Na+ current in one-third of the cells, whereas the Ca2+ and K+ currents were unaffected. Acute exposure to the phorbol ester increased the Ca2+ currents with little effect on the Na+ currents. The extent to which the differences in effects on membrane currents initiated by respective acute and long-term exposure to TPA may reflect two separate mechanisms of protein kinase C activation, the latter related to regulation of differentiation of the RINm5F cells, merits further investigation.

UR - http://www.scopus.com/inward/record.url?scp=0023036614&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0023036614&partnerID=8YFLogxK

M3 - Article

C2 - 2431624

AN - SCOPUS:0023036614

VL - 251

JO - American Journal of Physiology - Cell Physiology

JF - American Journal of Physiology - Cell Physiology

SN - 0363-6143

IS - 6

ER -