Background
Tecadenoson is an adenosine A1 receptor agonist (Ki = 6.5 nM).1 It is selective for adenosine A1 over A2 receptors (Ki = 2,315 nM). Tecadenoson prolongs stimulus-His bundle potential (SH) intervals in isolated perfused guinea pig hearts (EC50 = 40.6 nM). In vivo, tecadenoson induces PR interval prolongation in anesthetized guinea pigs (ED50 = 0.9 μg/kg) and reduces heart rate in anesthetized rats in a dose-dependent manner, without affecting blood pressure.
1.Cheung, J.W., and Lerman, B.B.CVT-510: A selective A1 adenosine receptor agonistCardiovasc. Drug Rev.21(4)277-292(2003)
Protocol
Kinase experiment: | The effect of Tecadenoson on binding to A1 and A2A-adenosine receptors of porcine forebrain and striatum membranes, respectively, are determined. Assays for A1 and A2A receptors are carried out by using the A1 receptor antagonist [3H]CPX and the A2A receptor agonist [3H]CGS?21680. Membranes are treated with adenosine deaminase (2?U/mL) for 20?min at room temperature prior to and during radioligand binding assays. Membranes (0.2-0.7?mg), adenosine deaminase, and the indicated radioligand are incubated for 3?h in a 300?μL volume of Tris-HCl buffer (50?mM) (pH?7.4). Assays are carried out in triplicate at room temperature. After the incubation period, bound and free radioligand are diluted by the addition of ice-cold Tris-HCl buffer (5?mL), and immediately separated by vacuum filtration of assay contents onto Whatman GF/C filters and ishing of trapped membranes with Tris-HCl buffer (20 mL). Filter disks containing membrane-bound radioactivity are placed in 4 mL Scintiverse, and the radioactivity is quantified by a liquid scintillation counter. Specific binding of [3H]CPX and [3H]CGS?21680 is defined as membrane binding displaced in the presence of CPT (10?μM) and R-PIA (10?μM), respectively[1]. |
Animal experiment: | Rat: The effects of Tecadenoson on heart rate and to reduce serum NEFA concentration are determined in separate groups of rats to avoid the effects of animal handling and blood sampling on heart rate. Three days before an experiment, a catheter (0.025-mm outer diameter) is implanted in the left common carotid artery of each rat using aseptic conditions and sterile technique. The catheter is tunneled subcutaneously to the dorsal surface. After recovery from anesthesia, rats are placed in metabolic cages to facilitate handling and blood sampling. Blood samples (0.2 mL) are drawn before and at various time points after i.p. injection of either Tecadenoson or vehicle (DMSO in saline). A 0.4-mL volume of 1% sodium citrate in saline is administered after withdrawal of each blood sample to replace blood volume and prevent clotting in the carotid artery catheter. Serum is collected from each sample after centrifugation of the clotted blood. Serum samples are stored at ?80°C until analysis. Serum NEFA concentration is determined using an enzymatic colorimetric assay kit[2]. |
参考文献: [1]. Snowdy S, et al. A comparison of an A1 adenosine receptor agonist (CVT-510) with diltiazem for slowing of AVnodal conduction in guinea-pig. Br J Pharmacol. 1999 Jan;126(1):137-46.
[2]. Fraser H, et al. N-[3-(R)-tetrahydrofuranyl]-6-aminopurine riboside, an A1 adenosine receptor agonist, antagonizes catecholamine-induced lipolysis without cardiovascular effects in awake rats. J Pharmacol Exp Ther. 2003 Apr;305(1):225-31. |
没有评价数据