IBMX (Methylisobutylxanthine) is a broad-spectrum phosphodiesterase (PDE) inhibitor with inhibitory activity against PDE3, PDE4, and PDE5 (IC50=6.5/26.3/31.7 μM). IBMX enhances the intracellular cAMP level.

PDE3:6.5 μM, PDE5:31.7 μM, PDE4:26.3 μM

方法：从 HK 喂养的大鼠分离的 CCD 用 IBMX (100 μM) 预处理 20 min，并检查 ANG II 或 cGMP 对通道活性的影响。
结果：IBMX 激活了 ROMK 通道并阻止了 ANG II 进一步激活通道。[1]
方法：豚鼠 TSMC 的原代培养物，在 IBMX (100 μM) 存在的情况下，检测 KMUP-1 对 cAMP 和 cGMP 水平的影响。
结果：IBMX 和 KMUP-1 显著增加了 cAMP 和 cGMP 水平。单独使用 KMUP-1 对 cAMP 和 cGMP 水平与在有 IBMX 的条件下没有显著差异。[2]
方法：哺乳动物细胞 CHO 用 IBMX (10-1000 μM) 处理，使用膜片钳技术测量全细胞电流。
结果：IBMX 对 THIK-1 电流影响的稳态剂量反应曲线可以拟合为 Hill 系数为 1 和 IC50 为 120 μM。[3]

方法：为检测对小鼠的代谢作用，将 IBMX (1 mg/kg) 皮下注射给小鼠，每天两次，持续七天。
结果：IBMX 显著增加了小鼠的血糖水平（血糖，mg/dl，对照=141，IBMX=210）。[4]
方法：为检测对高血糖小鼠的代谢作用，将葡萄糖 (0.5 g/kg) 和 IBMX (1 mg/kg) 股静脉注射给 Wistar 大鼠。
结果：在高血糖大鼠中，IBMX 能降低血糖，IBMX 不会改变血浆胰岛素水平，IBMX 降低了肝糖原储存。[4]

Intracellular cyclic GMP and cyclic AMP concentrations in guinea-pig TSMCs were assayed as previously described. In brief, cells were grown in 24-well plates 10^5 cells per well. At confluence, monolayer cells were washed with phosphate buffer solution (PBS) and then incubated with KMUP-1 (0.1–100 μM) in the presence of 100 μM IBMX for 20 min. Incubation was terminated by the addition of 10% trichloroacetic acid (TCA). Cell suspensions were sonicated and then centrifuged at 2500 × g for 15 min at 4°C. To remove TCA, the supernatants were extracted three times with 5 volumes of water-saturated diethyl ether. Then, the supernatants were lyophilized and the cyclic GMP or AMP of each sample was determined by using commercially available radioimmunoassay kits [1].

Male mice (25-35 g), obtained from the animal house of Faculty of Medicine, were kept in controlled environmental conditions (temperature: 23±2 oC; light-dark cycle: 7 a.m. to 7 p.m.) and were divided randomly into groups of seven. All test compounds were dissolved in DMSO and diluted to desired concentration with less than 1% DMSO. For the experiment, the test compound (IBMX, milrinone, MCPIP, mc1, mc2, mc5 or mc6) or solvent (control) was injected subcutaneously to mice at 1 mg/kg dosage twice a day (8:00 a.m. and 8:00 p.m.) for 7 days. On day 8, animals were anesthetized with intraperitoneal injection of thiopental (80 mg/kg) and blood samples were obtained from their hearts and then the liver was dissected. Each sample was centrifuged for 5 min and its serum was separated [3].