Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20366 (substance P)
 21,176 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied the effect of inhibiting phosphodiesterase (PDE) isozyme types III, IV and V on the cholinergic and noncholinergic (tachykinergic) contractile responses to electrical field stimulation (EFS) in the guinea pig isolated bronchus. SKF 94836, a PDE III inhibitor, had a slight (approximately 30%) but significant inhibitory effect on the noncholinergic contractions. Rolipram, an inhibitor of PDE IV isozymes, dramatically inhibited the noncholinergic contractions by nearly 70%. The EC50 for rolipram was approximately 20 nM. Rolipram (1 microM) had no effect on contractions elicited by either capsaicin or neurokinin A. EFS, but not direct vagus nerve stimulation, elicits small nonadrenergic, noncholinergic relaxations of the bronchus that were potentiated by rolipram. Rolipram had the same inhibitory effect on EFS- and vagus nerve stimulation-induced noncholinergic contractions. The effect of rolipram was mimicked by another PDE IV inhibitor, RO-201724. Inhibition of PDE V with zaprinast (3 microM) had no effect on the tachykinergic contractile response. None of the PDE inhibitors affected the EFS-induced cholinergic contractions. The data suggest that the contraction due to stimulation of tachykinergic fibers is significantly reduced by selective inhibition of PDE IV and, to a lesser extent, PDE III isozymes. This is unlikely to be due to functional antagonism at the level of the smooth muscle. It is also unlikely to be due to potentiation of the nonadrenergic relaxant response to nerve stimulation. Rather, the data are in agreement with the hypothesis that selective inhibition of PDE isozymes leads to inhibition of electrically evoked tachykinin release from capsaicin-sensitive fibers in the guinea pig bronchus.
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PMID:Inhibition of neurally mediated nonadrenergic, noncholinergic contractions of guinea pig bronchus by isozyme-selective phosphodiesterase inhibitors. 796

1. The activity of CDP840, a novel, potent and selective cyclic nucleotide phosphodiesterase type 4 (PDE 4) inhibitor, was evaluated in guinea-pig models (in vitro and in vivo) of bronchospasm, ozone-induced airway hyperresponsiveness (AHR) and non-cholinergic bronchoconstriction. Comparisons were made with (i) other PDE 4 inhibitors: CT1731 (S-enantiomer of CDP840), rolipram, RP73401 and (ii) the clinically used agents salbutamol and theophylline. 2. CDP840 relaxed isolated trachea, under basal tone (EC50 4.5 +/- 1.1 microM) being 17 fold less potent than rolipram (EC50 0.26 +/- 0.13 microM) but attaining the same Emax (83 +/- 6% of the response to 300 microM papaverine). 3. CDP840 relaxed tracheae pre-contracted with carbachol (IC25 39 +/- 9 microM) and histamine (IC25 4 +/- 1 microM) producing monophasic curves. Stereoselectivity was not observed with CT1731 against either carbachol (IC25 33 +/- 11 microM) or histamine (IC25 17 +/- 10 microM). Aminophylline was 1.6 fold (carbachol) and 11 fold (histamine) less potent than CDP840. Rolipram and RP73401 produced tri-phasic relaxation curves but were of similar potency (at the IC25 level) to CDP840 against carbachol (rolipram 18 +/- 5 microM, RP73401 39 +/- 1 microM) whereas against histamine they were approximately 20 fold more potent (rolipram 0.2 +/- 0.1 microM, RP73401 0.2 +/- 0.1 microM). In producing > 30% (carbachol) and > 60% (histamine) relaxation these inhibitors had similar potency and were poor compared to salbutamol. 4. Pre-incubation with CDP840 (10 microM) did not antagonize histamine-induced contraction of isolated trachea; however, it did cause a slight potentiation of the subsequent relaxation to salbutamol (IC50 23 +/- 1 to 15 +/- 2 nM). 5. Pretreatment (1 h) with either CDP840 (1 mg kg-1, i.p. or 3 mg kg-1, i.v.) or rolipram (1 mg kg-1, i.p.) did not bronchodilate or antagonize bronchospasm due to inhaled histamine in anaesthetized, ventilated guinea-pigs. Salbutamol (1 mg kg-1, i.p.) did not bronchodilate but caused a parallel 7 fold rightward shift in the histamine dose-response curve. 6. Stimulation of the vagus nerve in the presence of atropine resulted in a frequency-related bronchoconstriction. CDP840 and rolipram (i.v.) inhibited the response being approximately equipotent (EC50 approximately 10 micrograms kg-1). Neither drug inhibited bronchospasm to inhaled substance P. 7. CDP840 (1-10 micrograms kg-1 i.p.) dose relatedly inhibited ozone-induced bronchoconstriction. CT1731 (1 mg kg-1), rolipram (1 mg kg-1), RP73401 (10 micrograms kg-1) and aminophylline (10 mg kg-1) had no effect. Ozone-induced AHR to inhaled histamine was inhibited by CDP840 in a dose-related manner, 10 micrograms kg-1 abolishing the AHR. This effect was stereoselective as CT1731 was approximately 30 fold less potent than CDP840. Rolipram was approximately 100 fold less potent and RP73401 and aminophylline had no effect. CDP840 was orally active being approximately 10 fold less potent compared to i.p. administration. 8. CDP840 is a poor spasmolytic and anti-spasmogenic agent in response to exogenous mediators; however, it potently inhibits vagally mediated non-cholinergic bronchoconstriction and ozone-induced AHR to histamine. It is possible that regulation of cyclic AMP by PDE 4 contributes to neuronal sensitivity in the airways. Furthermore, CDP840 may suppress AHR without being an overt bronchodilator. Such a profile of activity may have therapeutic benefit in airways diseases such as asthma.
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PMID:Inhibition of bronchospasm and ozone-induced airway hyperresponsiveness in the guinea-pig by CDP840, a novel phosphodiesterase type 4 inhibitor. 881 43