Your browser has javascript turned off or blocked. This will lead to some parts of our website to not work properly or at all. Turn on javascript for best performance.

The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Maria Gomez

Maria Gomez

Professor

Maria Gomez

Differential actions of exogenous and intracellular spermine on contractile activity in smooth muscle of rat portal vein

Author

  • B O Nilsson
  • M Gomez
  • R Santiago Carrilho
  • I Nordström
  • P Hellstrand

Summary, in English

Effects of the naturally occurring polyamine spermine on electrical and contractile properties of the rat portal vein were studied. 1 mM spermine nearly abolished spike activity and spontaneous contractions and decreased the intracellular Ca2+ concentration ([Ca2+]i). The phasic force responses to 0.1 and 1 microM phenylephrine were partially inhibited, but not the sustain plateau contraction caused by 5 microM phenylephrine. The Ca(2+)-force relation in high-K+ (128 mM)-depolarized veins was shifted to the right, EC50 for Ca2+ increasing from 0.50 +/- 0.03 mM (control, n = 8) to 0.65 +/- 0.06 and to 0.94 +/- 0.03 at 1 (n = 4) and 10 (n = 3) mM spermine, respectively. However, at a Ca2+ concentration of 2.5 mM, giving maximal force, there was no effect of spermine (1 mM) on either force or [Ca2+]i. Whereas extracellular spermine thus reduced contractile activity at moderate levels of stimulation, increased intracellular concentration of spermine potentiated the force response to Ca2+. Intracellular loading of spermine by reversible permeabilization increased its concentration by 2-3 times. The spontaneous activity and response to phenylephrine were unchanged. However, the Ca(2+)-force relation of depolarized veins was shifted to the left, EC50 decreasing from 0.51 +/- 0.04 mM in controls (n = 7) to 0.36 +/- 0.02 mM in the loaded veins (n = 9). Spermine increased Ca(2+)-activated force in portal veins permeabilized with beta-escin. The degree of potentiation was consistent with observed effects in spermine-loaded intact veins. The results suggest that spermine at physiological intracellular concentration may contribute to the determination of Ca2+ sensitivity in vascular smooth muscle cells.

Department/s

  • Department of Experimental Medical Science
  • Vascular Physiology
  • Diabetic Complications
  • Cellular Biomechanics

Publishing year

1995-07

Language

English

Pages

65-355

Publication/Series

Acta Physiologica Scandinavica

Volume

154

Issue

3

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Cell and Molecular Biology

Keywords

  • Animals
  • Calcium
  • Calcium Channel Agonists
  • Electrophysiology
  • Escin
  • Female
  • Fura-2
  • In Vitro Techniques
  • Microelectrodes
  • Muscle Contraction
  • Muscle, Smooth, Vascular
  • Phenylephrine
  • Portal Vein
  • Rats
  • Rats, Sprague-Dawley
  • Spermine

Status

Published

Research group

  • Vascular Physiology
  • Diabetic Complications
  • Cellular Biomechanics

ISBN/ISSN/Other

  • ISSN: 0001-6772