Title: Identification of three isoforms of the InsP3 receptor in human myometrial smooth muscle
Authors: Morgan, J M ×
De Smedt, Humbert
Gillespie, J I #
Issue Date: Apr-1996
Series Title: Pflügers Archiv : European journal of physiology. vol:431 issue:5 pages:697-705
Abstract: The mechanisms responsible for the mobilisation of Ca2+ from intracellular stores sensitive to inositol trisphosphate (InsP3) were studied in saponin-permeabilised human myometrial cells in which the sarcoplasmic reticulum was pre-loaded with 45Ca2+. InsP3-induced 45Ca2+ release was measured over the InsP3 concentration range of 100 nM to 100 microM and showed a graded response. InsP3-induced 45Ca2+ release was inhibited by heparin (20-40 microg/ml) but not significantly affected by caffeine. The Ca2+ sensitivity of InsP3-induced Ca2+ release was measured under conditions which were designed to exclude interference with Ca2+ released by the ryanodine receptor/channel complex. The data showed a bell-shaped relationship with the InsP3 receptor (InsP3R) functional at 10 nM, becoming maximally activated at 300 nM but inhibited at 10 microM Ca2+. Messenger RNA encoding for three isoforms of InsP3R, type I, II and type III, was shown to be present. The relative expression levels of these messengers were obtained by ratio-PCR analysis and the levels of expression of the different isoforms were found to differ between individual patients.
ISSN: 0031-6768
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Molecular and Cellular Signaling
× corresponding author
# (joint) last author

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