Different phospholipase-C-coupled receptors differentially regulate capacitative and non-capacitative Ca2+ entry in A7r5 cells

• Published in: Biochemical journal 2005-08, Vol.389 (Pt 3), p.821-829
• Main Authors: Moneer, Zahid, Pino, Irene, Taylor, Emily J A, Broad, Lisa M, Liu, Yingjie, Tovey, Stephen C, Staali, Leila, Taylor, Colin W
• Format: Article
• Language: English
• Subjects: Animals; Arginine Vasopressin - physiology; Calcium - metabolism; Calcium Channels - physiology; Calcium Signaling - physiology; Cell Line; Humans; Membrane Microdomains - physiology; Muscle, Smooth, Vascular - physiology; Receptors, Cell Surface - physiology; Receptors, Serotonin - physiology; Receptors, Vasopressin - physiology; Serotonin - physiology; Type C Phospholipases - metabolism
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj20050145

Several receptors, including those for AVP (Arg8-vasopressin) and 5-HT (5-hydroxytryptamine), share an ability to stimulate PLC (phospholipase C) and so production of IP3 (inositol 1,4,5-trisphosphate) and DAG (diacylglycerol) in A7r5 vascular smooth muscle cells. Our previous analysis of the effects of AVP on Ca2+ entry [Moneer, Dyer and Taylor (2003) Biochem. J. 370, 439-448] showed that arachidonic acid released from DAG stimulated NO synthase. NO then stimulated an NCCE (non-capacitative Ca2+ entry) pathway, and, via cGMP and protein kinase G, it inhibited CCE (capacitative Ca2+ entry). This reciprocal regulation ensured that, in the presence of AVP, all Ca2+ entry occurred via NCCE to be followed by a transient activation of CCE only when AVP was removed [Moneer and Taylor (2002) Biochem. J. 362, 13-21]. We confirm that, in the presence of AVP, all Ca2+ entry occurs via NCCE, but 5-HT, despite activating PLC and evoking release of Ca2+ from intracellular stores, stimulates Ca2+ entry only via CCE. We conclude that two PLC-coupled receptors differentially regulate CCE and NCCE. We also address evidence that, in some A7r5 cells lines, AVP fails either to stimulate NCCE or inhibit CCE [Brueggemann, Markun, Barakat, Chen and Byron (2005) Biochem. J. 388, 237-244]. Quantitative PCR analysis suggests that these cells predominantly express TRPC1 (transient receptor potential canonical 1), whereas cells in which AVP reciprocally regulates CCE and NCCE express a greater variety of TRPC subtypes (TRPC1=6>2>3).