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- Title
Activation of sarcolemma and nuclear membranes ET-1 receptors regulates transcellular calcium levels in heart and vascular smooth muscle cells.
- Authors
Bkaily, Ghassan; Choufani, Sanaa; Sader, Sawsan; Jacques, Danielle; d'Orleans-Juste, Pedro; Nader, Moni; Kurban, Ghada; Karnal, Maud
- Abstract
The use of an ET-1 fluorescent probe in human heart and vascular smooth muscle cells showed that ET-1 receptors are present at both the sarcolemma and nuclear envelope membranes. The use of immunofluorescence studies showed that the ET[subA] receptor was mainly present at the sarcolemma and cytosolic levels. However, the ET[subB] receptor was present at the sarcolemma and the cytosol, as well as the nuclear envelope membranes and the nucleoplasm. In addition, ET-1 immunoreactivity was seen in the cytosol and the nucleus. Using Ca&sup2+;fluorescent probes such as Fluo-3, Indo 1, and yellow cameleon, as well as confocal microscopy three-dimensional image measurement technique, stimulation of ET-1 receptors at the sarcolemma membranes induced an increase of cytosolic and nuclear free Ca&sup2+; levels. This effect of extracellular ET-1 was blocked by removal of extracellular calcium. Direct stimulation of ET-1 receptors at the nuclear envelope membranes also induced an increase of intranuclear free Ca&sup2+; level. Our results suggest that the stimulation of sarcolemmal Ca&sup2+; influx by ET-1 seems to be due to the activation of ET[subA] and ET[subB] receptors. However, the increase of nucleoplasmic Ca&sup2+; levels by cytosolic ET-1 seems to be mediated via the activation of ET[subB] receptors. Activation of nuclear membranes ET[subB] receptors seems to prevent nuclear Ca&sup2+; overload and may protect the cell from apoptosis.
- Subjects
ENDOTHELINS; SARCOLEMMA; CALCIUM in the body; NUCLEAR receptors (Biochemistry); CONFOCAL microscopy
- Publication
Canadian Journal of Physiology & Pharmacology, 2003, Vol 81, Issue 6, p654
- ISSN
0008-4212
- Publication type
Article
- DOI
10.1139/y03-020