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Maria Gomez

Maria Gomez

Professor

Maria Gomez

Endogenous polyamines modulate Ca2+ channel activity in guinea-pig intestinal smooth muscle

Author

  • Maria Gomez
  • Per Hellstrand

Summary, in English

The polyamines spermine and spermidine inhibit L-type Ca2+ channels in whole-cell recordings from guinea-pig ileum cells (Gomez and Hellstrand, Pflugers Arch, 430:501-507, 1995 [4]). To study whether they modulate channel activity under physiological conditions, we further investigated their actions on Ca2+ channels and the effects of altered cellular polyamine contents. In inside-out patches, spermine (0.1-1 mM) inhibited channel activity without affecting the amplitude of unitary currents. In cell-attached recordings, addition of spermine to the bath did not influence channel activity in the patch, indicating that its extracellular action is direct and not mediated via passage of the polyamine through the cell membrane. Cellular contents of spermidine and spermine were decreased by about 50% by organ culture of ileum strips for 5 days with the adenosylmethionine decarboxylase inhibitor CGP 48664 (10 microM). This caused enhanced channel activity in cell-attached recordings, suggesting a reduced level of channel block by endogenous polyamines compared with control cells. Whole-cell recordings in the perforated patch mode showed increased current in polyamine-depleted cells, while this was not seen when cells were dialysed with the pipette solution. We conclude that polyamines block Ca2+ channels from the inside as well as the outside of the cell membrane, and that endogenous polyamines in smooth muscle modulate Ca2+ channel activity.

Department/s

  • Vascular Physiology

Publishing year

1999

Language

English

Pages

445-451

Publication/Series

Pflügers Archiv

Volume

438

Issue

4

Document type

Journal article

Publisher

Springer

Topic

  • Physiology

Keywords

  • Polyamine
  • Smooth muscle
  • Calcium channels

Status

Published

Research group

  • Vascular Physiology

ISBN/ISSN/Other

  • ISSN: 0031-6768