zaprinast and zardaverine

Inhalation of aerosolized prostaglandin I(2) (PGI(2)) causes selective pulmonary vasodilation, but the effect rapidly levels off after termination of nebulization. In experimental pulmonary hypertension in intact rabbits, provoked by continuous infusion of the stable thromboxane mimetic U46619, the impact of intravenous phosphodiesterase (PDE) inhibitors on pulmonary and systemic hemodynamics was investigated in the absence and the presence of aerosolized PGI(2). We employed the monoselective inhibitors motapizone (PDE 3), rolipram (PDE 4), and zaprinast (PDE 5), as well as the dual-selective blockers zardaverine and tolafentrine (both PDE 3/4). All PDE inhibitors dose-dependently reduced the pulmonary artery pressure (Ppa), with doses for an approximately 20% decrease in pulmonary vascular resistance being 5 microgram/kg for motapizone, 25 microgram/kg for rolipram, 500 microgram/kg for zardaverine, 1 mg/kg for zaprinast, and 1 mg/kg for tolafentrine. Additive efficacy was noted when combining the monoselective 3 plus 4, 3 plus 5, and 4 plus 5 inhibitors. In parallel with the pulmonary vasorelaxant effect, all PDE inhibitors caused a decrease in systemic arterial pressure and an increase in cardiac output. Nebulized PGI(2) (56 ng/kg. min) reduced the U46619-evoked increase in Ppa by approximately 30%. This vasorelaxant effect was fully lost within 10 min after termination of PGI(2) nebulization. Coapplication of subthreshold doses of intravenous PDE inhibitors, which per se did not affect pulmonary and systemic hemodynamics, resulted in a marked prolongation of the post-PGI(2) decrease in Ppa for all blockers (motapizone at 2.2 microgram/kg, rolipram at 5.5 microgram/kg, zaprinast at 100 microgram/kg). The most effective agents, zardaverine (50 microgram/kg) and tolafentrine (100 microgram/kg), augmented the maximum Ppa drop during nebulization by approximately 30-50% and prolonged the post-PGI(2) pulmonary vasodilation to > 30 min, without affecting systemic arterial pressure and arterial oxygenation. We conclude that subthreshold systemic doses of monoselective PDE 3, 4, and 5 inhibitors and in particular dual-selective PDE 3/4 inhibitors cause significant amplification of the pulmonary vasodilatory response to inhaled PGI(2), while limiting the hypotensive effect to the pulmonary circulation. Combining nebulized PGI(2) with low-dose systemic PDE inhibitors may thus offer a therapeutic strategy to achieve selective pulmonary vasodilation in acute and c

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Administration, Inhalation; Aerosols; Animals; Antihypertensive Agents; Blood Pressure; Cardiac Output; Dose-Response Relationship, Drug; Drug Therapy, Combination; Epoprostenol; Hypertension, Pulmonary; Naphthyridines; Phosphodiesterase Inhibitors; Pulmonary Circulation; Purinones; Pyridazines; Rabbits; Rolipram; Vasoconstrictor Agents; Vasodilation

The effects of the nonselective phosphodiesterase (PDE) inhibitor 3-isobutyl-1-methylxanthine (IBMX) and the selective PDE inhibitors motapizone (type III), rolipram (type IV), zardaverine (type III/IV), and zaprinast (type V and I) on prostaglandin F2 alpha (PFG2 alpha)-induced tone in human pulmonary arteries was investigated. Relaxation was achieved by IBMX [concentration eliciting 50% of maximum response (EC50): 11.3 microM, n = 10], motapizone (EC50:3.0 microM, n = 7), zardaverine (EC50: 3.2 microM, n = 9), and zaprinast (EC50: 31.8 microM, n = 6), whereas rolipram was almost ineffective. The combination of motapizone and zaprinast (10 microM) was the most effective relaxant with supra-additive relaxation and a motapizone EC50 of 575 nM. Biochemical studies revealed the presence of the PDE isozymes I, III, IV and V in the cytosolic and particulate phases of arterial homogenates; PDE II was not detectable. Partial inhibition of adenosine 3',5'-cyclic monophosphate (cAMP)-hydrolyzing PDE activity was achieved with rolipram (26 +/- 2.2%) or motapizone (60 +/- 5.4%), whereas there was almost complete inhibition of total PDE activity with zardaverine (81 +/- 2.0%) or the combination of motapizone and rolipram (82 +/- 2.3%). Inhibition of guanosine 3',5'-cyclic monophosphate (cGMP)-hydrolyzing PDE activity was achieved with zaprinast (62 +/- 2.6%) and motapizone (13 +/- 2.3%), indicating the cGMP-hydrolyzing activity of PDE III. We conclude that four out of the five recognized PDE isozyme families are present in human pulmonary artery. PGF2 alpha-induced tone in this tissue is effectively relaxed through PDE inhibitors with selectivity for type III, III/IV, and type V PDE.

Topics: 1-Methyl-3-isobutylxanthine; Adult; Aged; Antihypertensive Agents; Carbachol; Colforsin; Cytosol; Dinoprost; Dose-Response Relationship, Drug; Female; Humans; Isoenzymes; Kinetics; Lung Neoplasms; Male; Middle Aged; Muscle Contraction; Muscle Relaxation; Muscle Tonus; Muscle, Smooth, Vascular; Nitroprusside; Phosphodiesterase Inhibitors; Phosphoric Diester Hydrolases; Pulmonary Artery; Purinones; Pyridazines; Pyrrolidinones; Rolipram

The effects of the nonselective phosphodiesterase (PDE)-inhibitor 3-isobutyl-1-methylxanthine (IBMX) and the selective PDE inhibitors SKF 94120 (type III), rolipram (type IV), zardaverine (type III/IV), and zaprinast (type V) on inherent tone in human airways were investigated. Substantial relaxation was achieved by IBMX [concentration eliciting 50% of maximum response (EC50): 2.9 microM, n = 14] and SKF 94120 (EC50: 1.4 microM, n = 15); rolipram and zaprinast were almost ineffective. Zardaverine (EC50: 0.31 microM, n = 8), and the combination of SKF 94120 and rolipram (1 microM; EC50: 0.41 microM) were effective relaxants. Biochemical studies revealed the presence of PDE isozymes I, III, IV, and V in the cytosolic and particulate phase of airway homogenates, whereas PDE II was present only in the cytosol. Partial inhibition of total PDE adenosine 3',5'-cyclic monophosphate-hydrolyzing activity was achieved with rolipram and a selective type III inhibitor, whereas there was almost complete inhibition of total PDE activity with either zardaverine or the combination of type III and IV inhibitors. We conclude that all five PDE isozyme families are present in crude preparations of human peripheral airways. Inherent tone in this tissue is most effectively relaxed through selective type III/IV PDE inhibitors.

Topics: 1-Methyl-3-isobutylxanthine; 2',3'-Cyclic-Nucleotide Phosphodiesterases; Adult; Aged; Bucladesine; Colforsin; Dibutyryl Cyclic GMP; Dose-Response Relationship, Drug; Female; Forced Expiratory Volume; Humans; In Vitro Techniques; Isoenzymes; Lung; Lung Neoplasms; Male; Middle Aged; Muscle Relaxation; Muscle Tonus; Muscle, Smooth; Nitroprusside; Purinones; Pyrazines; Pyridazines; Pyrrolidinones; Rolipram; Vital Capacity

The effects of molsidomine and its metabolite linsidomine were studied on the guinea-pig isolated trachea and on the human isolated bronchus. These effects were compared with those of nitrate derivatives (sodium nitroprusside, isosorbide dinitrate), theophylline, zardaverine and isoprenaline. Linsidomine exerted a relaxant effect similar to that of sodium nitroprusside on the two types of preparations precontracted with acetylcholine, histamine or potassium chloride. Molsidomine was about one-hundredth as potent as linsidomine, and less efficacious. The effects of the two substances were not modified by removal of the human bronchial epithelium. The concentration-response curves of linsidomine and sodium nitroprusside were significantly shifted to the right by methylene blue (3 x 10(-5) M) but the effects of isoprenaline were unmodified. The effects of linsidomine and sodium nitroprusside were potentiated specifically by zaprinast (10(-6)-10(-5) M), an inhibitor of type Ia or V phosphodiesterases, whereas the effects of isoprenaline were potentiated by zardaverine (10(-9)-10(-8) M), an inhibitor of class III and IV phosphodiesterases. The effects of all three substances (linsidomine, isoprenaline and sodium nitroprusside) were potentiated equally by theophylline (10(-5)-10(-4) M), a nonspecific inhibitor of phosphodiesterases. It is concluded that linsidomine is a potent relaxant of the smooth muscle of the guinea-pig isolated trachea and human isolated bronchus. In terms of potency and efficacy, its effect is much superior to that of the parent compound molsidomine. It is suggested that linsidomine acts, like nitrate derivatives, through the guanylate cyclase-cGMP system.

Topics: Animals; Bronchi; Bronchodilator Agents; Epithelium; Guinea Pigs; Humans; In Vitro Techniques; Isoproterenol; Male; Methylene Blue; Molsidomine; Muscle, Smooth; Nitroprusside; Purinones; Pyridazines; Theophylline; Trachea