3-[(Imidazolidin-2-yl)imino]indazole ligands with selectivity for the α(2)-adrenoceptor compared to the imidazoline I(1) receptor

A series of 3-[(4,5-dihydroimidazolidin-2-yl)imino]indazoles has been synthesized as positional analogues of marsanidine, a highly selective ??₂-adrenoceptor ligand. Parent compound 4a and its 4-chloro (4c) and 4-methyl (4d) derivatives display ??₂-adrenoceptor affinity at nanomolar concentrations (K_i = 39.4, 15.9 and 22.6 nM, respectively) and relatively high ??₂/I₁ selectivity ratios of 82, 115 and 690, respectively. Evidence was obtained that these compounds act as partial agonists at ??_2A-adrenoceptors. Compound 4d with intrinsic activity comparable with that of marsanidine, but lower than that of clonidine, elicited pronounced cardiovascular effects in anesthetized rats at doses as low as 0.01 mg/kg iv     

植物新陈代谢(2)

(续 2 0 0 3年第 38卷第 7期第 4 5页 )3　能力训练3.1　实验设计 ,不仅有助于学生掌握基本概念和原理 ,更有助于学生掌握科学的研究方法 ,培养学生的创造性思维 ,培养学生应用所学知识综合解决问题的能力 ,是培养学生综合素质的有效手段。例题 1:设计一个实验 ,验证缺硼会影响油菜的结实率。 (答案 :略 )例题 2 :设计一个实验测定洋葱表皮细胞细胞液的质量分数 ?(利用质壁分离实验原理可测定细胞的质量分数 ,答案 :略 )3.2　研究影响酶作用因素实验方法　　研究某一因素对酶促反应速度的影响时 ,应在保持其他因素不变的情况下 ,单独改变研…