Platelet-derived growth factor regulates K-Cl cotransport in vascular smooth muscle cells

• Published in: American Journal of Physiology: Cell Physiology 2003-03, Vol.284 (3), p.C674-C680
• Main Authors: Zhang, Jing, Lauf, Peter K, Adragna, Norma C
• Format: Article
• Language: English
• Subjects: Animals; Cell Membrane - drug effects; Cell Membrane - metabolism; Cells, Cultured; Culture Media, Serum-Free - pharmacology; Dose-Response Relationship, Drug; K Cl- Cotransporters; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; Myocytes, Smooth Muscle - drug effects; Myocytes, Smooth Muscle - metabolism; Platelet-Derived Growth Factor - metabolism; Platelet-Derived Growth Factor - pharmacology; Proteins - drug effects; Proteins - metabolism; Rats; Rats, Sprague-Dawley; Receptors, Platelet-Derived Growth Factor - drug effects; Receptors, Platelet-Derived Growth Factor - metabolism; RNA, Messenger - drug effects; RNA, Messenger - metabolism; Symporters - drug effects; Symporters - genetics; Symporters - metabolism
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00312.2002

1  Department of Pharmacology and Toxicology; and 2  Physiology and Biophysics, Wright State University, School of Medicine, Dayton, Ohio 45435 Platelet-derived growth factor (PDGF), a potent serum mitogen for vascular smooth muscle cells (VSMCs), plays an important role in membrane transport regulation and in atherosclerosis. K-Cl cotransport (K-Cl COT/KCC), the coupled-movement of K and Cl, is involved in ion homeostasis. VSMCs possess K-Cl COT activity and the KCC1 and KCC3 isoforms. Here, we report on the effect of PDGF on K-Cl COT activity and mRNA expression in primary cultures of rat VSMCs. K-Cl COT was determined as the Cl-dependent Rb influx and mRNA expression by semiquantitative RT-PCR. Twenty four-hour serum deprivation inhibited basal K-Cl COT activity. Addition of PDGF increased total protein content and K-Cl COT activity in a time-dependent manner. PDGF activated K-Cl COT in a dose-dependent manner, both acutely (10 min) and chronically (12 h). AG-1296, a selective inhibitor of the PDGF receptor tyrosine kinase, abolished these effects. Actinomycin D and cycloheximide had no effect on the acute PDGF activation of K-Cl COT, suggesting posttranslational regulation by the drug. Furthermore, PDGF increased KCC1 and decreased KCC3 mRNA expression in a time-dependent manner. These results indicate that chronic activation of K-Cl COT activity by PDGF may involve regulation of the two KCC mRNA isoforms, with KCC1 playing a dominant role in the mechanism of PDGF-mediated activation. KCC1/KCC3; Rb influx; serum; AG-1296; mRNA expression