Surface charge, fluidity, and calcium uptake by rat intestinal brush-border vesicles

Harold P Schedl; Karla K Christensen; Eugene D Clark; Garry R Buettner

doi:10.1016/0005-2736(94)00260-V

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Surface charge, fluidity, and calcium uptake by rat intestinal brush-border vesicles

Journal article

Open access

Peer reviewed

Surface charge, fluidity, and calcium uptake by rat intestinal brush-border vesicles

Harold P Schedl, Karla K Christensen, Eugene D Clark and Garry R Buettner

Biochimica et biophysica acta. Biomembranes, Vol.1234(1), pp.81-89

1995

DOI: 10.1016/0005-2736(94)00260-V

PMID: 7880862

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Abstract

Biological membrane outer surfaces are negatively charged and interact with positively charged calcium ion during calcium uptake. Positively charged polycations such as polyarginine bind to membranes with high affinity, displacing bound calcium from the membrane. We tested the effect of polyarginine on uptake of calcium by brush-border membrane vecicles and examined the responses in terms of membrane fluidity by electron paramagnetic resonance (EPR). Polyarginine inhibited the saturable component of calcium uptake by a mechanism combining inhibition characteristics of strontium (competitive) and magnesium (non-competitive). Unlike the inhibition of non-saturable calcium uptake by strontium and magnesium, polyarginine increased k D, the rate constant for non-saturable calcium uptake, by a concentration dependent mechanism. These effects of polyarginine on calcium uptake were associated with decreased membrane fluidity at the uptake temperature. These findings are consistent with a role for surface negative charge in determining both saturable and non-saturable calcium uptake. Increased membrane fluidity is associated with decreased saturable and increased non-saturable calcium uptake. Although increased fluidity might be involved in the increased k D for non-saturable uptake, the concentration-specific stimulating effect of polyarginine suggests a gating mechanism.

Calcium ion transport

Brush-border membrane vesicle

Polycation

Inhibition

Intestine

EPR

Details

Title: Subtitle: Surface charge, fluidity, and calcium uptake by rat intestinal brush-border vesicles
Creators: Harold P Schedl
Karla K Christensen
Eugene D Clark
Garry R Buettner
Resource Type: Journal article
Publication Details: Biochimica et biophysica acta. Biomembranes, Vol.1234(1), pp.81-89
DOI: 10.1016/0005-2736(94)00260-V
PMID: 7880862
NLM abbreviation: Biochim Biophys Acta Biomembr
ISSN: 0005-2736
eISSN: 1879-2642
Publisher: Elsevier B.V
Language: English
Date published: 1995
Academic Unit: Radiation Oncology; Nursing
Record Identifier: 9984047632802771

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