Intracellular cAMP potentiates voltage-dependent activation of L-type Ca2+ channels in rat islet β-cells

Takahiro Kanno, Sechiko Suga, Jie Wu, Masao Kimura, Makoto Wakui

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Intracellular cAMP-dependent modulation of L-type Ca2+ channel activation in cultured rat islet β-cells has been investigated using the patch-clamp whole-cell current recording mode. The-L-type voltage-dependent Ca2+ current (I(Ca)) showed a fast activation followed by a slow inactivation, and was sensitive to Ca2+ channel blockers, for example nifedipine. Application of a cAMP analogue, dibutyryl cyclic AMP (db-cAMP), increased the magnitude of the peak I(Ca) in a concentration-dependent manner. Values of the half-activation potentials (V( 1/4 )), taken from activation curves for I(Ca), were -16.7 ± 1.8 and -21.9 ± 3.4 mV (P < 0.05) before and after application of db-cAM, respectively, with no change of the slope factor (k) or the reversal potential. Pretreatment with a specific protein kinase A antagonist, Rp-cAMP, prevented the potentiating effect of db-cAMP. These results indicate that in rat islet β-cells, phosphorylation of cAMP-dependent kinase potentiates the voltage-dependent activation of L-type Ca2+ channels.

Original languageEnglish (US)
Pages (from-to)578-580
Number of pages3
JournalPflugers Archiv European Journal of Physiology
Volume435
Issue number4
DOIs
StatePublished - 1998
Externally publishedYes

Keywords

  • Ca channel
  • Cyclic AMP
  • Islet β-cells
  • Patch-clamp

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)

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