PDE3 (IC50 = 6.5 μM); PDE4 (IC50 = 26.3 μM); PDE5 (IC50 = 31.7 μM)

The most efficient concentrations for inducing airway relaxation were 100 μM for both KMUP-1 (a xanthine peptide inducer) and IBMX; there was no discernible variation in the activation of the induction response triggered by either compound [1]. Renal outer medulla K+ (ROMK) channels were activated (n=6, P<0.05) by IBMX (100 μM), while ANG II (n=6, P=NS) or cGMP could not further activate these channels. Notably, tubular cAMP content increased significantly to 1.43±0.35 pg/mm tubule length (n =14) after 20 minutes of sham-containing nutrient collecting ducts (CCDs) isolated from high K+ (HK)-fed scaffolds with IBMX (100 μM) compared to tubule length measured in vehicle-treated controls (0.61±0.13 pg/mm tubule length, n =12, P<0.05)[2].

Liver glycogen reserves are considerably reduced by IBMX, a non-selective PDE (mg/g, IBMX 22±1.5 P<0.001). IBMX and mc5 were found to significantly increase cardiac signs (glucose, mg/dl, control=141±3, IBMX=210±17 P<0.001 and mc5=191±13 P<0.01) when compared to serum. In contrast, compounds from mc1, mc6, MCPIP, and Win 47203 did not significantly affect any of the subjects (control=141±3, mc1 160±7, mc6 175±9, MCPIP 179±8, and Win 47203 116±2 P>0.05). mc2 was not found to alter the umbilical cord scale (control=141±3 and mc2=145±5). When it comes to boosting cardiovascular core, IBMX is the most effective [3]. While apocynin and IBMX treatment did not significantly lower cold exposure in the right ventricle (RV), they did considerably minimize the cold-induced increase in systolic blood pressure (23.5 ± 1.8 and 24.2 ± 0.6 mmHg, respectively). The lumen diameter increases to 62.7 ± 4.2 and 59.5 ± 4.3 μM, respectively, while the thickness of the PA medial layer is 19.0 ± 0.9 and 16.9 ± 0.8 μM, respectively] [4].

Measurement of cAMP content in single CCDs.[2]
Multiple individual CCDs were microdissected from a single kidney in cold Ringer solution within 1 h of euthanization of the rat, and total lengths of ∼10 mm were transferred to a 1.5-ml microcentrifuge tube to generate a single sample. Thereafter, fresh Ringer solution (50 μl) was added to each tube, and samples were allowed to equilibrate to room temperature for 5 min. Next, samples were centrifuged, the supernatant was removed, and Ringer solution (50 μl) with IBMX (100 μM) or vehicle (DMSO) alone was added. After incubation at room temperature for 20 min, samples were centrifuged, and the supernatant was stored at −80°C. For measurements of extracellular cAMP, samples of the supernatant were boiled 5 min at 95°C and then centrifuged, and 45 μl of the supernatant were mixed with 5 μl of the internal standard solution and then subjected to direct analysis. To extract intracellular cAMP from CCDs, 0.5 ml of ice-cold 1-propanol was added to the tissue pellet, and samples were placed in the cold room at 4°C on a shaker for 2 h; 1-propanol extracts were stored at −80°C. For analysis of intracellular cAMP, 1-propanol samples were taken to dryness, reconstituted in 100 μl pure water, and then centrifuged at 8,000 rpm for 10 min. Samples (90 μl) were mixed with 10 μl of internal standard solution, and this was subjected to direct analysis. cAMP measurements were performed by HPLC-tandem mass spectrometry using a triple quadrupole mass spectrometery as previously described in detail (37, 38). For each sample, total CCD cAMP content was calculated as the sum of the cAMP content measured in the extracts of single tubules plus that detected in the supernatant normalized to tubule length (in mm).

Cells are grown in 24-well plates 105 cells per well. At confluence, monolayer cells are 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 is terminated by the addition of 10% trichloroacetic acid (TCA). Cell suspensions are sonicated and then centrifuged at 2500× g for 15 min at 4°C. To remove TCA, the supernatants are extracted three times with 5 volumes of water-saturated diethyl ether. Then, the supernatants are lyophilized and the cyclic GMP or AMP of each sample is determined by using commercially available radioimmunoassay kits[2].

Mice[3]
Male mice (25-35 gram) were used in the experiment. The test compounds (IBMX, MCPIP, mc1, mc2, mc5 or mc6) or solvent (control) were injected subcutaneously to mice at 1 mg/kg dosage twice a day (8:00 a.m. and 8:00 p.m.) for 7 days.
Rats[4]
Six groups of male Sprague-Dawley rats were used (150-180g, 6 rats/group). Three groups of rats are exposed to a climate-controlled walk-in chamber maintained at moderate cold (5.0±1°C). The remaining groups are kept in an identical chamber maintained at room temperature (23.5±1°C, warm) and served as controls. After eight weeks of exposure to cold, 3 groups in each temperature condition received continuous IV infusion of IBMX (PDE-1 inhibitor, 8.5 mg/kg/day), Apocynin (NADPH oxidase inhibitor, 25 mg/kg/day) and vehicle (DMSO, 50%), respectively. The doses of drugs have been validated for effective inhibition of PDE-1 and NADPH oxidase activity, respectively. Body weight is measured weekly. After one week of drug infusion, the animals’ right ventricular systolic blood pressure (RVBP) is measured under anesthesia. The RVP is a reliable indicator of pulmonary arterial blood pressure (PAP) and has been used by numerous investigators for evaluating PH.

mouse LD50 intraperitoneal 44 mg/kg European Journal of Medicinal Chemistry--Chimie Therapeutique., 25(653), 1990

[1]. KMUP-1, a xanthine derivative, induces relaxation of guinea-pig isolated trachea: the role of the epithelium, cyclic nucleotides and K+ channels. Br J Pharmacol. 2004 Aug;142(7):1105-14.

[2]. Angiotensin II type 2 receptor regulates ROMK-like K+ channel activity in the renal cortical collecting duct during high dietary K+ adaptation. Am J Physiol Renal Physiol. 2014 Oct 1;307(7):F833-43.

[3]. Differential metabolic effects of novel cilostamide analogs, methyl carbostiryl derivatives, on mouse and hyperglycemic rat. Iran J Basic Med Sci. 2012 Jul;15(4):916-25.

[4]. Inhibition of phosphodiesterase-1 attenuates cold-induced pulmonary hypertension. Hypertension. 2013 Mar;61(3):585-92.

3-isobutyl-1-methyl-9H-xanthine is a 3-isobutyl-1-methylxanthine. It is functionally related to a 9H-xanthine. It is a tautomer of a 3-isobutyl-1-methyl-7H-xanthine.
A potent cyclic nucleotide phosphodiesterase inhibitor; due to this action, the compound increases cyclic AMP and cyclic GMP in tissue and thereby activates CYCLIC NUCLEOTIDE-REGULATED PROTEIN KINASES.

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7-[2-[4-(2-chlorophenyl)piperazinyl]ethyl]-1,3-dimethylxanthine (KMUP-1) produces tracheal relaxation, intracellular accumulation of cyclic nucleotides, inhibition of phosphodiesterases (PDEs) and activation of K+ channels. KMUP-1 (0.01-100 microm) induced concentration-dependent relaxation responses in guinea-pig epithelium-intact trachea precontracted with carbachol. Relaxation responses were also elicited by the PDE inhibitors theophylline, 3-isobutyl-1-methylxanthine (IBMX), milrinone, rolipram and zaprinast (100 microm), and a KATP channel opener, levcromakalim. Tracheal relaxation induced by KMUP-1 was attenuated by epithelium removal and by pretreatment with inhibitors of soluble guanylate cyclase (sGC) (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), 1 microm), nitric oxide synthase (Nomega-nitro-L-arginine methyl ester, 100 microm), K+ channels (tetraethylammonium, 10 mm), KATP channels (glibenclamide, 1 microm), voltage-dependent K+ channels (4-aminopyridine, 100 microm) and Ca2+-dependent K+ channels (charybdotoxin, 0.1 microm or apamin, 1 microm). Both KMUP-1 (10 microm) and theophylline nonselectively and slightly inhibited the enzyme activity of PDE3, 4 and 5, suggesting that they are able to inhibit the metabolism of adenosine 3',5'-cyclic monophosphate (cyclic AMP) and guanosine 3',5'-cyclic monophosphate (cyclic GMP). Likewise, the effects of IBMX were also measured and its IC50 values for PDE3, 4 and 5 were 6.5 +/- 1.2, 26.3 +/- 3.9 and 31.7 +/- 5.3 microm, respectively. KMUP-1 (0.01-10 microm) augmented intracellular cyclic AMP and cyclic GMP levels in guinea-pig cultured tracheal smooth muscle cells. These increases in cyclic AMP and cyclic GMP were abolished in the presence of an adenylate cyclase inhibitor SQ 22536 (100 microm) and an sGC inhibitor ODQ (10 microm), respectively. KMUP-1 (10 microm) increased the expression of protein kinase A (PKARI) and protein kinase G (PKG1alpha1beta) in a time-dependent manner, but this was only significant for PKG after 9 h. Intratracheal administration of tumour necrosis factor-alpha (TNF-alpha, 0.01 mg kg(-1)) induced bronchoconstriction and exhibited a time-dependent increase in lung resistance (RL) and decrease in dynamic lung compliance (Cdyn). KMUP-1 (1.0 mg kg(-1)), injected intravenously for 10 min before the intratracheal TNF-alpha, reversed these changes in RL and Cdyn. These data indicate that KMUP-1 activates sGC, produces relaxation that was partly dependent on an intact epithelium, inhibits PDEs and increases intracellular cyclic AMP and cyclic GMP, which then increases PKA and PKG, leading to the opening of K+ channels and resulting tracheal relaxation.[1]

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The kidney adjusts K⁺ excretion to match intake in part by regulation of the activity of apical K⁺ secretory channels, including renal outer medullary K⁺ (ROMK)-like K⁺ channels, in the cortical collecting duct (CCD). ANG II inhibits ROMK channels via the ANG II type 1 receptor (AT1R) during dietary K⁺ restriction. Because AT1Rs and ANG II type 2 receptors (AT2Rs) generally function in an antagonistic manner, we sought to characterize the regulation of ROMK channels by the AT2R. Patch-clamp experiments revealed that ANG II increased ROMK channel activity in CCDs isolated from high-K⁺ (HK)-fed but not normal K⁺ (NK)-fed rats. This response was blocked by PD-123319, an AT2R antagonist, but not by losartan, an AT1R antagonist, and was mimicked by the AT2R agonist CGP-42112. Nitric oxide (NO) synthase is present in CCD cells that express ROMK channels. Blockade of NO synthase with N-nitro-l-arginine methyl ester and free NO with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt completely abolished ANG II-stimulated ROMK channel activity. NO enhances the synthesis of cGMP, which inhibits phosphodiesterases (PDEs) that normally degrade cAMP; cAMP increases ROMK channel activity. Pretreatment of CCDs with IBMX, a broad-spectrum PDE inhibitor, or cilostamide, a PDE3 inhibitor, abolished the stimulatory effect of ANG II on ROMK channels. Furthermore, PKA inhibitor peptide, but not an activator of the exchange protein directly activated by cAMP (Epac), also prevented the stimulatory effect of ANG II. We conclude that ANG II acts at the AT2R to stimulate ROMK channel activity in CCDs from HK-fed rats, a response opposite to that mediated by the AT1R in dietary K⁺-restricted animals, via a NO/cGMP pathway linked to a cAMP-PKA pathway.[2]

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Objective(s): PDE3 has a functional role in insulin secretion and action. We investigated the metabolic effects of new synthetic PDE3 inhibitors (mc1, mc2, mc5 and mc6), on mice and hyperglycemic rat. Materials and methods: The test compound or solvent was injected subcutaneously to mice, for 7 days. On day 8, blood and liver samples were obtained. In hyperglycemic rat, 0.5 g/kg glucose with or without test compounds was injected, and followed with infusion of 1.5 g/kg/hr glucose. Blood samples were collected in mentioned intervals and liver was dissected. Results: In hyperglycemic rat, all test compounds decreased blood glucose and the effect of milrinone was potentiated by glybenclamide. Milrinone or IBMX did not change plasma insulin levels, but it was augmented by combination of milrinone and glybenclamide. In both species, liver glycogen storage was decreased by IBMX, mc5, mc6 or MCPIP, increased by mc2 (liver glycogen, rat, control=56±2, mc2=70±3 P< 0.01, mice, control=33±0.7, mc2=42±2.3 P< 0.01) and was not changed in the presence of mc1. Milrinone did not change the glycogen storage in rats though increased it in mice (control= 33±0.7, milrinone= 40±1 P< 0.05). Conclusion: Increasing plasma insulin levels by combination of milrinone and glybenclamide confirmed that in hyperglycemic rat, the hypoglycemic effect was correlated with increasing insulin secretion. Variations of plasma insulin were obscured by the pulsative characteristic of pancreatic insulin release. Decreasing glycogen storage reflected inhibition of liver PDE activity. The reasons for ineffectiveness of mc1, anabolic effect of mc2, and differential effects of milrinone were not clear. [3]

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Chronic exposure to cold caused pulmonary arterial hypertension (cold-induced pulmonary hypertension [CIPH]) and increased phosphodiesterase-1C (PDE-1C) expression in pulmonary arteries (PAs) in rats. The purpose of this study is to investigate a hypothesis that inhibition of PDE-1 would decrease inflammatory infiltrates and superoxide production leading to attenuation of CIPH. Three groups of male rats were exposed to moderate cold (5±1°C) continuously, whereas 3 groups were maintained at room temperature (23.5±1°C, warm; 6 rats/group). After 8-week exposure to cold, 3 groups in each temperature condition received continuous intravenous infusion of 8-isobutyl-methylxanthine (8-IBMX) (PDE-1 inhibitor), apocynin (NADPH oxidase inhibitor) or vehicle, respectively, for 1 week. Cold exposure significantly increased right-ventricular systolic pressure compared with warm groups (33.8±3.2 versus 18.6±0.3 mm Hg), indicating that animals developed CIPH. Notably, treatment with 8-IBMX significantly attenuated the cold-induced increase in right ventricular pressure (23.5±1.8 mm Hg). Cold exposure also caused right-ventricular hypertrophy, whereas 8-IBMX reversed cold-induced right ventricular hypertrophy. Cold exposure increased PDE-1C protein expression, macrophage infiltration, NADPH oxidase activity, and superoxide production in PAs and resulted in PA remodeling. 8-IBMX abolished cold-induced upregulation of PDE-1C in PAs. Interestingly, inhibition of PDE-1 eliminated cold-induced macrophage infiltration, NADPH oxidase activation, and superoxide production in PAs and reversed PA remodeling. Inhibition of NADPH oxidase by apocynin abolished cold-induced superoxide production and attenuated CIPH and PA remodeling. In conclusion, inhibition of PDE-1 attenuated CIPH and reversed cold-induced PA remodeling by suppressing macrophage infiltration and superoxide production, suggesting that upregulation of PDE-1C expression may be involved in the pathogenesis of CIPH. [4]

C10H14N4O2

222.25

222.111

C, 54.04; H, 6.35; N, 25.21; O, 14.40

28822-58-4

IBMX;28822-58-4

3758

White to light yellow sosild

1.3±0.1 g/cm3

445.6±37.0 °C at 760 mmHg

200-201 °C(lit.)

223.3±26.5 °C

0.0±1.1 mmHg at 25°C

1.569

1.24

1

3

2

16

318

0

O=C1N(C([H])([H])[H])C(C2=C(N=C([H])N2[H])N1C([H])([H])C([H])(C([H])([H])[H])C([H])([H])[H])=O

APIXJSLKIYYUKG-UHFFFAOYSA-N

InChI=1S/C10H14N4O2/c1-6(2)4-14-8-7(11-5-12-8)9(15)13(3)10(14)16/h5-6H,4H2,1-3H3,(H,11,12)

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 1.67 mg/mL (7.51 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 16.7 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: 1.67 mg/mL (7.51 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 16.7 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 1.67 mg/mL (7.51 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 16.7 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: ≥ 0.71 mg/mL (3.19 mM) (saturation unknown) in 10% EtOH + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 7.1 mg/mL clear EtOH stock solution to 400 μL of PEG300 and mix evenly; then add 50 μL of Tween-80 to the above solution and mix evenly; then add 450 μL of normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 5: ≥ 0.71 mg/mL (3.19 mM) (saturation unknown) in 10% EtOH + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 7.1 mg/mL clear EtOH stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 6: ≥ 0.71 mg/mL (3.19 mM) (saturation unknown) in 10% EtOH + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 7.1 mg/mL clear EtOH stock solution to 900 μL of corn oil and mix well.

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 (Please use freshly prepared in vivo formulations for optimal results.)