Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, 100 Technology Dr, Suite 450, Pittsburgh, PA 15219, USA.
Hypertension. 2010 Jul;56(1):151-8. doi: 10.1161/HYPERTENSIONAHA.110.152454. Epub 2010 Jun 1.
Recently we discovered that intact kidneys release into the extracellular compartment 2',3'-cAMP (a positional isomer of 3',5'-cAMP with unknown pharmacology) and metabolize 2',3'-cAMP to 2'-AMP, 3'-AMP, and adenosine. Because adenosine inhibits growth of vascular smooth muscle cells and mesangial cells, we tested the hypothesis that extracellular 2',3'-cAMP attenuates growth of preglomerular vascular smooth muscle and mesangial cells via production of adenosine. For comparison, all of the experiments were performed with both 2',3'-cAMP and 3',5'-cAMP. In study 1, 2',3'-cAMP, 3',5'-cAMP, 5'-AMP, 3'-AMP, or 2'-AMP was incubated with cells and purines measured in the medium by mass spectrometry. Both preglomerular vascular smooth muscle and mesangial cells metabolized 3',5'-cAMP to 5'-AMP and adenosine; 5'-AMP to adenosine; 2',3'-cAMP to 2'-AMP, 3'-AMP, and adenosine; and 2'-AMP and 3'-AMP to adenosine. 3-Isobutyl-1-methylxanthine (phosphodiesterase inhibitor) and 1,3-dipropyl-8-p-sulfophenylxanthine (ecto-phosphodiesterase inhibitor) blocked conversion of 3',5'-cAMP to 5'-AMP and adenosine, and alpha,beta-methylene-adenosine-5'-diphosphate (CD73 inhibitor) blocked conversion of 5'-AMP to adenosine. These enzyme inhibitors had little effect on metabolism of 2',3'-cAMP, 2'-AMP, or 3'-AMP. For study 2, 2',3'-cAMP and 3',5'-cAMP profoundly inhibited proliferation (thymidine incorporation and cell number) of both cell types, with 2',3'-cAMP more potent than 3',5'-cAMP. Antagonism of A(2B) receptors (MRS-1724), but not A(1) (1,3-dipropyl-8-cyclopentylxanthine), A(2A) (SCH-58261), or A(3) (VUF-5574) receptors, attenuated the growth inhibitory effects of 2',3'-cAMP and 3',5'-cAMP. Extracellular 2',3'-cAMP inhibits growth of preglomerular vascular smooth muscle and mesangial cells more profoundly than does 3',5'-cAMP. Although both cAMPs inhibit growth in part via conversion to adenosine followed by A(2B) receptor activation, their metabolism is mediated by different enzymes.
最近，我们发现完整的肾脏会将 2'，3'-cAMP（3'，5'-cAMP 的位置异构体，具有未知的药理学）释放到细胞外间隙中，并将 2'，3'-cAMP 代谢为 2'-AMP、3'-AMP 和腺苷。由于腺苷抑制血管平滑肌细胞和肾小球系膜细胞的生长，我们检验了这样一个假设，即细胞外 2'，3'-cAMP 通过产生腺苷来减弱肾小球前血管平滑肌和肾小球系膜细胞的生长。为了进行比较，我们使用 2'，3'-cAMP 和 3'，5'-cAMP 进行了所有实验。在研究 1 中，将 2'，3'-cAMP、3'，5'-cAMP、5'-AMP、3'-AMP 或 2'-AMP 与细胞孵育，并通过质谱法测量培养基中的嘌呤。肾小球前血管平滑肌细胞和肾小球系膜细胞均将 3'，5'-cAMP 代谢为 5'-AMP 和腺苷；5'-AMP 转化为腺苷；2'，3'-cAMP 转化为 2'-AMP、3'-AMP 和腺苷；2'-AMP 和 3'-AMP 转化为腺苷。3-异丁基-1-甲基黄嘌呤（磷酸二酯酶抑制剂）和 1,3-二丙基-8-对磺基苯基黄嘌呤（外切磷酸二酯酶抑制剂）阻断了 3'，5'-cAMP 转化为 5'-AMP 和腺苷，而 α，β-亚甲基-腺苷-5'-二磷酸（CD73 抑制剂）阻断了 5'-AMP 转化为腺苷。这些酶抑制剂对 2'，3'-cAMP、2'-AMP 或 3'-AMP 的代谢几乎没有影响。在研究 2 中，2'，3'-cAMP 和 3'，5'-cAMP 强烈抑制两种细胞类型的增殖（胸苷掺入和细胞数量），2'，3'-cAMP 的作用比 3'，5'-cAMP 更强。A(2B)受体（MRS-1724）拮抗剂，但不是 A(1)（1,3-二丙基-8-环戊基黄嘌呤）、A(2A)（SCH-58261）或 A(3)（VUF-5574）受体，减弱了 2'，3'-cAMP 和 3'，5'-cAMP 的生长抑制作用。细胞外 2'，3'-cAMP 比 3'，5'-cAMP 更能显著抑制肾小球前血管平滑肌和肾小球系膜细胞的生长。尽管两种 cAMPs 都通过转化为腺苷，然后激活 A(2B)受体，在一定程度上抑制生长，但它们的代谢是由不同的酶介导的。
