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 Physiologica Scandinavica
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.
(Less)
- author
- Nilsson, B O
LU
; Gomez, M
LU
; Santiago Carrilho, R
; Nordström, I
LU
and Hellstrand, P
LU
- organization
- publishing date
- 1995-07
- type
- Contribution to journal
- publication status
- published
- subject
- 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 Physiologica Scandinavica
- volume
- 154
- issue
- 3
- pages
- 11 pages
- publisher
- Wiley-Blackwell
- external identifiers
-
- scopus:0029041971
- pmid:7572233
- ISSN
- 0001-6772
- DOI
- 10.1111/j.1748-1716.1995.tb09919.x
- language
- English
- LU publication?
- yes
- id
- 44c139b4-f361-492f-b260-0d5106cb5cfd
- date added to LUP
- 2016-06-17 16:41:16
- date last changed
- 2024-01-04 08:28:04
@article{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}},
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}},
language = {{eng}},
number = {{3}},
pages = {{65--355}},
publisher = {{Wiley-Blackwell}},
series = {{Acta Physiologica Scandinavica}},
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}},
doi = {{10.1111/j.1748-1716.1995.tb09919.x}},
volume = {{154}},
year = {{1995}},
}