AJP - Cell Physiology, Vol 269, Issue 6 C1506-C1512, Copyright © 1995 by American Physiological Society

ARTICLES

Astroglial cell-induced expression of Na-K-Cl cotransporter in brain microvascular endothelial cells

D. Sun, C. Lytle and M. E. O'Donnell
Department of Human Physiology, School of Medicine, University of California, Davis 95616, USA.

Endothelial cells of the blood-brain barrier (BBB) are characterized by extensive tight junctions and asymmetric distribution of specific enzymes and transport systems. Maintenance of the BBB endothelial phenotype depends on astrocyte-endothelial interactions. We showed previously that cultured cerebral microvascular endothelial cells (CMEC) exhibit robust Na-K-Cl cotransport activity. In the present study, we evaluated the expression of Na-K-Cl cotransport protein in CMEC by quantitative Western blot analysis and found that a protein of approximately 170 kDa was recognized by a monoclonal antibody against the cotransporter. Exposure of CMEC to astroglial cells or their conditioned media increased the expression of the CMEC cotransport protein by approximately 55%. Using a monoclonal antibody against the alpha-subunit of chicken Na-K-ATPase, we found that these treatments also increased expression of Na-K-ATPase protein by a similar amount. By comparing bumetanide-sensitive K influx and [3H]bumetanide binding apical vs. basolateral surfaces of CMEC, we found both cotransporter activity and [3H]bumetanide binding to be approximately 90% apical and 10% basolateral. Coculture of the CMEC with astroglial cells increased cotransport activity and [3H]bumetanide binding at both surfaces, with the asymmetric distribution maintained. These results indicate that the cotransporter is regulated by astroglial cells and that an apically distributed CMEC cotransporter may function in tandem with the basolateral Na-K-ATPase to mediate vectorial transport of Na and Cl across the BBB.

This article has been cited by other articles:

				J. Brillault, T. I. Lam, J. M. Rutkowsky, S. Foroutan, and M. E. O'Donnell Hypoxia effects on cell volume and ion uptake of cerebral microvascular endothelial cells Am J Physiol Cell Physiol, January 1, 2008; 294(1): C88 - C96. [Abstract] [Full Text] [PDF]

				S. F. Pedersen, M. E. O'Donnell, S. E. Anderson, and P. M. Cala Physiology and pathophysiology of Na+/H+ exchange and Na+-K+-2Cl- cotransport in the heart, brain, and blood Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2006; 291(1): R1 - R25. [Abstract] [Full Text] [PDF]

				S. Foroutan, J. Brillault, B. Forbush, and M. E. O'Donnell Moderate-to-severe ischemic conditions increase activity and phosphorylation of the cerebral microvascular endothelial cell Na+-K+-Cl- cotransporter Am J Physiol Cell Physiol, December 1, 2005; 289(6): C1492 - C1501. [Abstract] [Full Text] [PDF]

				M. E. O'Donnell, V. Duong, J. Suvatne, S. Foroutan, and D. M. Johnson Arginine vasopressin stimulation of cerebral microvascular endothelial cell Na-K-Cl cotransporter activity is V1 receptor and [Ca] dependent Am J Physiol Cell Physiol, August 1, 2005; 289(2): C283 - C292. [Abstract] [Full Text] [PDF]

				S. L. Schomberg, G. Su, R. A. Haworth, and D. Sun Stimulation of Na-K-2Cl Cotransporter in Neurons by Activation of Non-NMDA Ionotropic Receptor and Group-I mGluRs J Neurophysiol, June 1, 2001; 85(6): 2563 - 2575. [Abstract] [Full Text] [PDF]

				A. FRIGERI, G. P. NICCHIA, B. NICO, F. QUONDAMATTEO, R. HERKEN, L. RONCALI, and M. SVELTO Aquaporin-4 deficiency in skeletal muscle and brain of dystrophic mdx mice FASEB J, January 1, 2001; 15(1): 90 - 98. [Abstract] [Full Text] [PDF]

				G. Su, R. A. Haworth, R. J. Dempsey, and D. Sun Regulation of Na+-K+-Cl- cotransporter in primary astrocytes by dibutyryl cAMP and high [K+]o Am J Physiol Cell Physiol, December 1, 2000; 279(6): C1710 - C1721. [Abstract] [Full Text] [PDF]

				N. D. Tran, J. Correale, S. S. Schreiber, M. Fisher, and P. H. Chan Transforming Growth Factor-{beta} Mediates Astrocyte-Specific Regulation of Brain Endothelial Anticoagulant Factors • Editorial Comment Stroke, August 1, 1999; 30(8): 1671 - 1678. [Abstract] [Full Text] [PDF]

				D. Sun and S. G. Murali Na+-K+-2Cl- Cotransporter in Immature Cortical Neurons: A Role in Intracellular Cl- Regulation J Neurophysiol, April 1, 1999; 81(4): 1939 - 1948. [Abstract] [Full Text] [PDF]

				L. M. Maglova, W. E. Crowe, P. R. Smith, A. A. Altamirano, and J. M. Russell Na+-K+-Cl- cotransport in human fibroblasts is inhibited by cytomegalovirus infection Am J Physiol Cell Physiol, November 1, 1998; 275(5): C1330 - C1341. [Abstract] [Full Text] [PDF]

				D. Sun and S. G. Murali Stimulation of Na+-K+-2Cl- cotransporter in neuronal cells by excitatory neurotransmitter glutamate Am J Physiol Cell Physiol, September 1, 1998; 275(3): C772 - C779. [Abstract] [Full Text] [PDF]