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IP3-activated Ca2+ channels in the plasma membrane of cultured vascular endothelial cells

IP3-activated Ca2+ channels in the plasma membrane of cultured vascular endothelial cells Although it is clear that D-myo-inositol 1,4,5-trisphosphate (IP3) plays an important role in the activation of Ca2+ influx, the mechanisms by which this occurs remain controversial. In an attempt to determine the role of IP3 in the activation of Ca2+ influx, patch-clamp single-channel experiments in the cell-attached, inside-out, and outside-out configurations were performed on cultured bovine aortic endothelial cells (BAEC). The results presented indicate that both IP3 and intracellular Ca2+ can modulate the activity of a Ca(2+)-selective channel found in the plasma membrane of these cells. Addition of 10 microM IP3 increased channel open probability (P(o)) from a control value of 0.12 +/- 0.05 to 0.7 +/- 0.13 at a constant intracellular Ca2+ of 1 nM in excised inside-out patches. D-Myo-inositol 1,3,4,5-tetrakisphosphate at 50 microM was ineffective in altering channel P(o). Channel activity declined after approximately 2 min in the continuous presence of IP3. Three to four minutes after addition of IP3, channel P(o) was reduced from 0.7 +/- 0.2 to 0.2 +/- 0.1, indicating that an additional regulator might be required to maintain channel activity in excised patches. The channel was reversibly blocked by application of 1 microgram/ml heparin to the intracellular side of inside-out patches. This Ca(2+)-selective channel is indistinguishable from the depletion-activated Ca2+ channel we have previously described in BAEC. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png AJP Cell Physiology The American Physiological Society

IP3-activated Ca2+ channels in the plasma membrane of cultured vascular endothelial cells

Vaca, L.; Kunze, D. L.
AJP Cell Physiology , Volume 269 (3) – Sep 1, 1995
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References (20)

ISSN
0363-6143
eISSN
1522-1563
DOI
10.1152/ajpcell.1995.269.3.C733
Publisher site
See Article on Publisher Site

Abstract

Although it is clear that D-myo-inositol 1,4,5-trisphosphate (IP3) plays an important role in the activation of Ca2+ influx, the mechanisms by which this occurs remain controversial. In an attempt to determine the role of IP3 in the activation of Ca2+ influx, patch-clamp single-channel experiments in the cell-attached, inside-out, and outside-out configurations were performed on cultured bovine aortic endothelial cells (BAEC). The results presented indicate that both IP3 and intracellular Ca2+ can modulate the activity of a Ca(2+)-selective channel found in the plasma membrane of these cells. Addition of 10 microM IP3 increased channel open probability (P(o)) from a control value of 0.12 +/- 0.05 to 0.7 +/- 0.13 at a constant intracellular Ca2+ of 1 nM in excised inside-out patches. D-Myo-inositol 1,3,4,5-tetrakisphosphate at 50 microM was ineffective in altering channel P(o). Channel activity declined after approximately 2 min in the continuous presence of IP3. Three to four minutes after addition of IP3, channel P(o) was reduced from 0.7 +/- 0.2 to 0.2 +/- 0.1, indicating that an additional regulator might be required to maintain channel activity in excised patches. The channel was reversibly blocked by application of 1 microgram/ml heparin to the intracellular side of inside-out patches. This Ca(2+)-selective channel is indistinguishable from the depletion-activated Ca2+ channel we have previously described in BAEC.

Journal

AJP Cell Physiology – The American Physiological Society

Published: Sep 1, 1995

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