It can be considered that extracellular application of VDCC blockers required too much time for the full Ang II effects to appear. synaptic inputs of both peripheral and central origins. Voltage-dependent Ca2+ channels (VDCCs) serve as crucial mediators of membrane excitability and Ca2+-dependent functions such as neurotransmitter release, enzyme activity and gene expression. The modulation of VDCCs is usually believed to be an important means of regulating Ca2+ influx and Duocarmycin SA thus has a direct influence on many Ca2+-dependent processes. Modulation of VDCCs by Ang II has been previously explained in various types of cells. However, the effect of Ang II on VDCCs in NTS has not yet been clarified, and little is known about transmission transduction pathways in NTS. Tyrosine phosphorylation is an important regulator of cell function (Schlessinger & Ullrich, 1992). Furthermore, increased tyrosine phosphorylation is usually associated with increased intracellular Ca2+ concentration ([Ca2+]i) during cell proliferation and migration. Even though mechanisms linking tyrosine phosphorylation to the changes in [Ca2+]i are not fully comprehended, in some cases increased opening of VDCCs has been proposed to underlie this effect (Hughes, 1995). Several studies have exhibited that tyrosine kinase modulates VDCCs in a variety of cell types (Cataldi 1996), suggesting that tyrosine phosphorylation may be a ubiquitous regulatory mechanism for VDCCs. Consequently, it is the purpose of this study to investigate the effects of Ang II on VDCC currents (1981). Fabricated recording pipettes (2C3 M) were filled with internal solution of the following composition (mm): 100 CsCl, 1 MgCl2, 10 Hepes, 10 BAPTA, 3.6 MgATP, 14 Tris2phosphocreatine (CP) and 0.1 GTP, plus 50 U ml?1 COL1A2 creatine phosphokinase (CPK). The pH was adjusted to 7.2 with CsOH. The inclusion of CP and CPK Duocarmycin SA effectively reduced rundown of is the concentration of Ang II, and is the Hill coefficient. Analysis and statistics All data analyses were performed using the pCLAMP 8.0 acquisition system. Values in text and figures are expressed as mean s.e.m. Statistical analysis was carried out using Student’s test for comparisons between pairs of groups and one-way analysis of variance (ANOVA) followed by Dunnett’s test. Probability (and 0.05 compared with control, ANOVA. = 5). Mean shows that progressive increases in Ang II concentration resulted in progressively greater facilitation of = 12, 6 and 5, respectively, Fig. 2 0.05 compared with control, ANOVA. These results indicate that Ang II-induced facilitation of = 7, 7 and 7, respectively). These results suggest that the Gi-proteins are involved in the Ang II-induced facilitation of and = 4). All experiments were performed in the presence of 5.3 mm KCl in the external solution (observe Methods). To ensure that all inward currents resulted from Ca2+ influx through VDCCs, i.e. to avoid the possibility of K+ influx, Cd2+ was applied after each selective VDCC blocker. As shown in Fig. 3and 0.05 compared with L + R types, ANOVA. We then investigated which types of VDCCs were facilitated by Ang II. When Nif (10 m) +-Aga IVA (1 m) and Nif +-CgTx GVIA (1 m) were applied first, the resistant = 5 and 5, respectively). On the other hand, when -CgTx GVIA +-Aga IVA were applied first, the resistant = 6, Fig. 3= 4). After application of Ang II, mean = 5). These results exhibited that Ang II facilitated L-type VDCCs, without significantly affecting N- and P/Q-type VDCCs in NTS. As shown in Fig. 3= 20 Duocarmycin SA and 6, respectively). It can be considered that extracellular application of VDCC blockers required too much time for the full Ang II effects to appear. As shown in Fig. 31989), is known to be activated by Ang II. In vascular easy muscle cells, Ang II is also known to activate several.