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

Nilsson, B O LU ; Gomez, M LU ; Santiago Carrilho, R; Nordström, I LU and Hellstrand, P LU (1995) In Acta Physiol.Scand 154(3). p.65-355
Abstract

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,... (More)

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.

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published
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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
in
Acta Physiol.Scand
volume
154
issue
3
pages
11 pages
publisher
Wiley-Blackwell
external identifiers
  • Scopus:0029041971
ISSN
0001-6772
DOI
10.1111/j.1748-1716.1995.tb09919.x
language
English
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yes
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44c139b4-f361-492f-b260-0d5106cb5cfd
date added to LUP
2016-06-17 16:41:16
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2016-10-13 05:10:16
@misc{44c139b4-f361-492f-b260-0d5106cb5cfd,
  abstract     = {<p>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.</p>},
  author       = {Nilsson, B O and Gomez, M and Santiago Carrilho, R and Nordström, I and Hellstrand, P},
  issn         = {0001-6772},
  keyword      = {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},
  language     = {eng},
  number       = {3},
  pages        = {65--355},
  publisher    = {ARRAY(0x8446d68)},
  series       = {Acta Physiol.Scand},
  title        = {Differential actions of exogenous and intracellular spermine on contractile activity in smooth muscle of rat portal vein},
  url          = {http://dx.doi.org/10.1111/j.1748-1716.1995.tb09919.x},
  volume       = {154},
  year         = {1995},
}