zaprinast and Hypersensitivity

With several notable exceptions, interest in the area of multiple molecular forms of phosphodiesterase remained relatively dormant during the decade following Thompson's discovery of more than one phosphodiesterase in brain in 1971. Within the last several years, however, over 20 novel agents have been identified that exert selective inhibitory effects on the various molecular forms of phosphodiesterase present within different cells. In addition, several studies have documented that such agents can produce discrete changes in cyclic AMP and cyclic GMP, an action that is not shared by "first generation" phosphodiesterase inhibitors such as theophylline. The purpose of this Perspective is to provide some clarity to this rapidly evolving area of selective phosphodiesterase inhibitors. Thus, we have attempted to characterize the different forms of phosphodiesterase present in various tissues and cells according to their kinetic properties, substrate specificity, etc. and also to characterize those major classes of agents that have been shown to inhibit phosphodiesterase activity, whether selectively or nonselectively. In addition, we have described several therapeutic areas wherein selective phosphodiesterase inhibitors might prove efficacious, paying particular attention to those areas in which selective phosphodiesterase inhibitors have already been shown to exert beneficial effects, namely, stimulation of myocardial contractility, inhibition of mediator release, and inhibition of platelet aggregation. Although focusing on these three areas, it is obvious that the potential therapeutic utility of selective phosphodiesterase inhibitors could conceivably extend to several other areas in which modulation of cyclic nucleotides can have desirable effects, including cancer chemotherapy, analgesia, the treatment of depression, Parkinson's disease, and learning and memory disorders. For example, the selective type III phosphodiesterase inhibitor rolipram has been shown to antagonize reserpine-induced hypothermia and also to potentiate yohimbine lethality, two tests that are indicative of antidepressant activity. In addition, microinjection of the selective PDE III inhibitor Ro 20-1724 into the rat brain stem has been shown to produce analgesia.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: 3',5'-Cyclic-AMP Phosphodiesterases; 3',5'-Cyclic-GMP Phosphodiesterases; Animals; Blood Platelets; Calmodulin; Cardiotonic Agents; Guinea Pigs; Humans; Hypersensitivity; In Vitro Techniques; Lung Diseases; Myocardium; Platelet Aggregation; Substrate Specificity

Several known antiallergic agents, including cromolyn sodium and a series of pyrido[2,1-b]quinazolines, inhibit human alkaline phosphatase (ALP), a membranal enzyme associated with calcium uptake in certain tissues. A comparison of ALP and rat passive cutaneous anaphylaxis (PCA) inhibition indicates that PCA inhibition may be associated with drug-ALP interaction, since ALP inhibition potency parallels PCA inhibitory activity. The unpredictability of the PCA test toward clinical efficacy could in part be related to the uncompetitive nature of these inhibitors. The results also suggest that alkaline phosphatase may be a component of membranal calcium channels.

Topics: Alkaline Phosphatase; Animals; Chemical Phenomena; Chemistry; Cromolyn Sodium; Female; Humans; Hypersensitivity; In Vitro Techniques; Leukocytes; Passive Cutaneous Anaphylaxis; Placenta; Pregnancy; Quinazolines; Rats

Antianaphylactic properties have been attributed to cyclic nucleotide phosphodiesterase inhibitors through increase of cyclic AMP levels, according to the concept that increases in cyclic AMP reduce release and increases in cyclic GMP enhance release. However, Coulson et al. [3] showed that the inhibition of histamine release from human lung is correlated to the inhibition of cyclic GMP hydrolysis. We studied the effect of specific inhibitors of cyclic AMP and cyclic GMP hydrolysis on the antigen-induced mediator release from rat mass cells and human basophils and on airways relaxation [4]. The results suggested that the modulation of mediator release was different from one cell type to the other, enhancement of cyclic AMP levels leading to the inhibition of release from basophils, while cyclic GMP appears to be predominantly involved in mast cells. The present paper shows that high concentrations of sodium nitrite, a stimulating agent of guanylate cyclase, inhibit histamine release from rat mast cells in the presence or absence of M&B 22948, a selective cyclic GMP phosphodiesterase inhibitor.

Topics: 3',5'-Cyclic-GMP Phosphodiesterases; Animals; Antigens; Aza Compounds; Histamine Release; Hypersensitivity; In Vitro Techniques; Male; Mast Cells; Nitrites; Purinones; Rats; Rats, Inbred Strains; Sodium Nitrite