guanylyl-imidodiphosphate and Asthma

Leukotriene (LT) D4 receptor in the granulation tissue formed in the air pouch-type allergic inflammation model in rats was analyzed. Membrane preparation of the granulation tissue obtained 3-9 days after the antigen challenge has specific binding sites of [3H]LTD4. Scatchard analysis showed that the affinity (Kd) and the density (Bmax) were not changed among the granulation tissue obtained 3-9 days after the antigen challenge. The Kd value in the granulation tissue (0.90 +/- 0.12 nM) was close to that in the rat lung (1.00 +/- 0.24 nM) and the guinea pig lung (0.86 nM). On the other hand, Bmax (62 +/- 8 fmol/mg protein) in the granulation tissue was higher than that in the rat lung (21 +/- 4 fmol/mg protein) but was far less than that in the guinea pig lung (405 fmol/mg protein). LTC4 and LTE4 inhibited the binding of [3H]LTD4 to the membrane preparation of the granulation tissue in a concentration-dependent manner. IC50 of LTC4 and LTE4 were 1 x 10(-7) and 2 x 10(-7) M, respectively. A guanine nucleotide, guanyl-5'-yl-imido-diphosphate (GppNHp), reduced [3H]LTD4 binding to the membrane preparation of the granulation tissue suggesting that LTD4 receptors in the granulation tissue are associated with G proteins. These results indicate that LTD4 binding sites in the granulation tissue are high affinity receptors for LTD4. A possible role of LTD4 in the recurrence of allergic inflammation in the chronic phase is discussed.

Topics: Animals; Asthma; Bronchial Hyperreactivity; Bronchitis; Cell Membrane; Disease Models, Animal; Granulation Tissue; GTP-Binding Proteins; Guanylyl Imidodiphosphate; Leukotriene E4; Male; Rats; Rats, Sprague-Dawley; Receptors, Immunologic; Receptors, Leukotriene; Specific Pathogen-Free Organisms; SRS-A

To clarify the mechanism of beta adrenergic hyporesponsiveness, which is related to bronchial hypersensitivity in asthmatic patients, cAMP responsiveness in peripheral lymphocytes was examined. The cAMP response to isoproterenol significantly decreased in the lymphocytes from asthmatics compared with those from healthy subjects. In contrast, the responses to GTP, Gpp(NH)p (a GTP analogue), sodium fluoride, and forskolin (a direct stimulator of the catalytic unit) were similar between the two groups. These results suggest that impairment of the stimulatory GTP binding protein or the catalytic unit is not the major cause of beta adrenergic hyporesponsiveness in asthma, and that hyporesponsiveness may be due to other mechanisms in the hormone-sensitive adenylate cyclase system.

Topics: Adenylyl Cyclases; Adolescent; Adult; Aged; Asthma; Colforsin; Cyclic AMP; Female; GTP-Binding Proteins; Guanylyl Imidodiphosphate; Humans; Isoproterenol; Lymphocytes; Male; Middle Aged; Receptors, Adrenergic, beta

Allergen challenge of allergic patients with asthma caused various changes in the beta-receptor-adenylate cyclase system of lymphocyte membranes from these patients. These changes included uncoupling and down regulation of beta-adrenergic receptors and nonspecific refractoriness of adenylate cyclase, as demonstrated by reduced responses to isoproterenol (beta 2), histamine (H2), 5'-guanylylimidodiphosphate, and sodium fluoride. Since these changes could be due to desensitization by enhanced plasma levels of catecholamines and/or histamine during the allergic response, we explored the effects of these agonists on the beta-receptor-adenylate cyclase system in vitro with normal lymphocytes. In addition, we assessed the effect of the tumor-promoting phorbol ester, phorbol 12-myristate 13-acetate (PMA), on this system, since phorbol esters have been demonstrated to modulate several receptor systems, presumably via activation of protein kinase C. That both the agonists and PMA may cause refractoriness of lymphocyte adenylate cyclase was demonstrated, but, however, by apparently different mechanisms. The agonists isoproterenol and histamine induced only a specific desensitization of the homologous responses, whereas PMA-induced refractoriness was nonspecific in nature. Radioligand-binding studies demonstrated that both uncoupling and down regulation contributed to the isoproterenol-induced beta-adrenergic hyporesponsiveness, whereas beta-adrenergic receptor uncoupling but not beta-adrenergic receptor down regulation was involved in PMA-induced desensitization. Histamine had no effect on the beta-adrenergic system at all. The data suggest that the agonist-induced changes in the adenylate cyclase system are specifically located at the receptors, whereas PMA-induced refractoriness can be explained by alterations distal to the receptors, presumably at the stimulatory guanine nucleotide regulatory protein. Thus, enhanced levels of catecholamines or histamine could be involved in the development of receptor-specific changes in the lymphocyte adenylate cyclase system of allergic patients with asthma. However, they are unlikely to cause the nonspecific changes distal to the receptors. The latter changes could be induced by physiologic activation of protein kinase C during the allergic response by a still unknown stimulus, possibly via the receptor-mediated turnover of phosphatidylinositol 4,5-diphosphate.

Topics: Adenylyl Cyclases; ADP-Ribosylation Factors; Adult; Asthma; Bronchial Provocation Tests; Carrier Proteins; Enzyme Activation; Female; Guanylyl Imidodiphosphate; Histamine; Humans; In Vitro Techniques; Isoproterenol; Lymphocytes; Male; Membrane Proteins; Protein Kinase C; Receptors, Adrenergic, beta; Sodium Fluoride; Tetradecanoylphorbol Acetate

Adenylate cyclase responses to isoproterenol, histamine, 5'-guanylylimidodiphosphate (GppNHp) and NaF were measured in lymphocyte membranes of allergic asthmatic patients and healthy control subjects, just before and 24 h after inhalation challenge with house dust mite allergen or histamine. In the nonacute phase before the challenges, the adenylate cyclase responses in the cell membranes of the patients were not significantly different from those in membranes of the control subjects. House dust mite challenge caused a significant decrease of all adenylate cyclase responses in the cell membranes of the patients by about 40-50%. By contrast, histamine provocation of the patients had no effect on these parameters, nor was there any effect of both challenges on the adenylate cyclase activity of the control membranes. The results indicate that allergen-induced asthmatic reactions may cause nonspecific refractoriness of lymphocyte adenylate cyclase. Since histamine-induced bronchial obstruction had no effect in the patients, it appears that the adenylate cyclase response is specifically modulated by the allergic process.

Topics: Adenylyl Cyclases; Adolescent; Adult; Allergens; Asthma; Bronchial Provocation Tests; Female; Guanylyl Imidodiphosphate; Histamine; Humans; Hypersensitivity; Isoproterenol; Lymphocytes; Male; Receptors, Adrenergic, beta; Sodium Fluoride

Beta-adrenergic receptor characteristics and adenylate cyclase responses to different stimuli were measured in lymphocyte membrane preparations of six normal control subjects and five allergic asthmatic patients with mild airways disease and increased bronchial reactivity to histamine and acetylcholine. The determinations were performed just before and 24 hr after inhalation challenge with house-dust mite antigen to investigate the influence of an allergen-induced asthmatic attack on the beta-adrenergic receptor system. Before the house-dust mite challenge, the lymphocyte membranes of the patients showed a normal receptor density, dissociation constant for (-)3H-dihydroalprenolol, and adenylate cyclase response to isoproterenol, guanyl-5'-yl-imidodiphosphate, (GppNHp) and NaF. After the allergen-induced asthmatic reaction, however, the beta-adrenergic receptor number in the patients was significantly reduced by 21%, while the basal adenylate cyclase activity and isoproterenol-, GppNHp-, and NaF-induced cyclic AMP responses were simultaneously reduced by about 40%. The allergen challenge had no significant effect on the lymphocyte membranes of the control subjects. These results suggest (1) that a reduced beta-adrenergic function is not an intrinsic component of allergic bronchial asthma but is rather the consequence of an active disease state, and (2) that next to changes in beta-adrenergic receptor number, alterations distal to the receptor may play an important role in the observed decrease in beta-adrenergic responsiveness.

Topics: Adenylyl Cyclases; Adolescent; Adult; Allergens; Asthma; Bronchial Provocation Tests; Dihydroalprenolol; Forced Expiratory Volume; Guanylyl Imidodiphosphate; Humans; Isoproterenol; Lymphocytes; Male; Mites; Receptors, Adrenergic; Receptors, Adrenergic, beta