title: Measurement of intracellular free calcium ion concentration in vascular smooth muscle cells : fluorescence imaging of cytosolic calcium.
abstract: Changes in intracellular free calcium ion concentration ([Ca(2+)](i)) play a major role in vascular smooth muscle cell function (1,2). Elevation of [Ca(2+)](i) is an important regulator of multiple downstream signaling pathways and it is a major determinant of vascular smooth muscle contraction (1-3). Agonists, such as angiotensin II (Ang II), endothelin-1, and vasopressin, that mediate effects through G protein-coupled receptors, increase [Ca(2+)](i) by inducing Ca(2+)mobilization from intracellular sarcoplasmic/endoplasmic reticular stores, and by stimulating transplasmalemmal Ca(2+)influx (4-6). One of the earliest measurable events resulting from Ang II stimulation of vascular smooth muscle cells, is a rapid, phospholipase C (PLC)-mediated hydrolysis of phosphatidylinositol 4,5-bisphosphate, to produce two second messengers, 1,2 diacylglycerol and inositol 1,4,5-trisphosphate (IP(3)) (7,8). The water-soluble messenger IP(3), binds to specific IP(3) receptors to release Ca(2+)from nonmitochondrial intracellular stores.
authors.affiliation: Laboratory of Experimental Hypertension, Clinical Research Institute of Montréal, Montréal, Québec, Canada.
authors.forename: R M
authors.initials: RM
authors.lastname: Touyz
authors.forename: E L
authors.initials: EL
authors.lastname: Schiffrin