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Pflügers Archiv

, Volume 423, Issue 3–4, pp 181–188 | Cite as

Effects of phorbol ester on gap junctions of neonatal rat heart cells

  • Pamela N. Münster
  • Robert Weingart
Excitable Tissues and Central Nervous Physiology

Abstract

Myocytes were isolated from the ventricles of neonatal rat hearts and cultured for 1–3 days. Newly formed cell pairs were used to examine the conductance of gap junctions, gj. Measurements were performed using a dual voltage-clamp method in conjunction with a whole-cell, tight-seal recording. Exposure to the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA, 100–160 nM) led to a decrease in gj. Single-channel events recorded immediately before complete uncoupling yielded a single-channel conductance, γj, of 40.5 pS, implying that TPA affects the channel kinetics rather than γj. TPA-induced uncoupling was observed at subphysiological levels of cytosolic Ca2+ (pipette solution=18 nM), not at physiological levels (pipette solution=170 nM). The effects of TPA could not be mimicked by 250 μM 1-oleoyl-2-acetyl-glycerol (OAG). Preincubation with TPA (up to 24 h) revealed no changes in gj attributable to down-regulation of protein kinase C, PKC. Pretreatment with PKC inhibitors, staurosporine or PKCI, prevented the TPA-dependent decrease in gj. TPA-dependent uncoupling was not impaired by 4-bromophenacyl bromide, an inhibitor of phospholipase A2, PLA2; conversely, an arachidonic acid-dependent decrease in gj was not prevented by PKCI. This suggests that gj regulation does not involve an interaction between PLA2 and PKC.

Key words

Neonatal rat heart Cardiac cells Gap junctions Electrical coupling Phorbol ester Protein kinase C 

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Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Pamela N. Münster
    • 1
  • Robert Weingart
    • 1
  1. 1.Department of PhysiologyUniversity of BernBernSwitzerland

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