Chemotaxis of vascular smooth muscle cells (VSMCs) is integral to the development of atherosclerosis and post-angioplasty restenosis. We have shown that chemotaxis of cultured rat VSMCs in a Boyden chamber is dependent on the gradient of the chemoattractant, platelet-derived growth factor (PDGF), and occurs infrequently and asynchronously among cells (only 10% chemotaxis within 4 hrs). We examined whether intracellular calcium (Cai) signaling mediates chemotaxis and could contribute to the asynchronous migratory response. In order to evaluate Cai in individual migrating VSMCs, we adapted a Boyden chemotaxis chamber to an imaging microscope which allows simultaneous measurement of locomotion and Cai in VSMCs (loaded with the Cai indicator, fura-2) during chemotaxis. There are two distinct, sequential cellular Cai signaling phases in response to a PDGF gradient: (1) an initial phase (time frame of minutes), with a relatively synchronous, transient increase in Cai in most cells, and (2) a delayed phase (time frame of hours), with asynchronous increases in Cai among individual cells which precede chemotaxis. The Cai achieved by migrating VSMCs was significantly higher compared to non-migrating VSMCs (mean Cai : 630 plus/minus 33 nM and 266 O 18 nM, respectively). Neither chemotaxis nor late increases in Cai were observed in VSMCs in the absence of PDGF or of its gradient. The PDGF gradient, which apparently conveys information that uniform- concentration exposure does not, is necessary for the late phase Cai responses in migrating cells. Buffering the late increase (but not the early increase) in Cai with intracellularly-loaded BAPTA significantly attenuated chemotaxis. The late Cai increase which occurs during chemotaxis results, in part, from trans-sarcolemmal Ca(2+) influx, as chemotaxis varied directly with extracellular Ca(2+). This Ca(2+) influx occurs through non-L-type Ca(2+) channels. In migrating VSMCs, the late Cai increase is coincident with activation of calcium/calmodulin-dependent protein kinase II (CaMK II), requisite during VSMC chemotaxis, which may facilitate essential cytoskeletal remodeling. Thus, changes in Cai mediate VSMC chemotaxis, and differences in Cai signaling within individual cells contributes to the asynchronous chemotactic response within VSMC populations.
| Zorov, Dmitry B; Juhaszova, Magdalena; Yaniv, Yael et al. (2009) Regulation and pharmacology of the mitochondrial permeability transition pore. Cardiovasc Res 83:213-25 |
| Ahmet, Ismayil; Spangler, Edward; Shukitt-Hale, Barbara et al. (2009) Blueberry-enriched diet protects rat heart from ischemic damage. PLoS One 4:e5954 |
| Moon, Chanil; Krawczyk, Melissa; Paik, Doojin et al. (2006) Erythropoietin, modified to not stimulate red blood cell production, retains its cardioprotective properties. J Pharmacol Exp Ther 316:999-1005 |
| Zorov, Dmitry B; Juhaszova, Magdalena; Sollott, Steven J (2006) Mitochondrial ROS-induced ROS release: an update and review. Biochim Biophys Acta 1757:509-17 |
| Juhaszova, Magdalena; Rabuel, Christophe; Zorov, Dmitry B et al. (2005) Protection in the aged heart: preventing the heart-break of old age? Cardiovasc Res 66:233-44 |
| Zorov, Dmitry B; Kobrinsky, Evgeny; Juhaszova, Magdalena et al. (2004) Examining intracellular organelle function using fluorescent probes: from animalcules to quantum dots. Circ Res 95:239-52 |
| Juhaszova, Magdalena; Zorov, Dmitry B; Kim, Suhn-Hee et al. (2004) Glycogen synthase kinase-3beta mediates convergence of protection signaling to inhibit the mitochondrial permeability transition pore. J Clin Invest 113:1535-49 |
| Lakatta, Edward G; Sollott, Steven J (2002) Perspectives on mammalian cardiovascular aging: humans to molecules. Comp Biochem Physiol A Mol Integr Physiol 132:699-721 |
| Lakatta, E G; Sollott, S J; Pepe, S (2001) The old heart: operating on the edge. Novartis Found Symp 235:172-96; discussion 196-201, 217 |
| Zorov, D B; Filburn, C R; Klotz, L O et al. (2000) Reactive oxygen species (ROS)-induced ROS release: a new phenomenon accompanying induction of the mitochondrial permeability transition in cardiac myocytes. J Exp Med 192:1001-14 |
