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J L Ortiz

Publications and source records attributed to J L Ortiz.

At least 19 recordsLinked to original sources
PubMed2000

Histamine up-regulates phosphodiesterase 4 activity and reduces prostaglandin E2-inhibitory effects in human neutrophils.

OBJECTIVE: To investigate whether histamine produces up-regulation of phosphodiesterase (PDE) activity with functional consequences in human peripheral blood neutrophils. METHODS: PDE activity was studied by a radioisotopic method following anion-exchange chromatography. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used for detection of mRNA transcripts of PDE4 subtypes. Cyclic AMP (cAMP) levels were measured by enzyme-immunoassay, and superoxide generation by cytochrome c reduction. TREATMENT: Neutrophils were incubated for 4 h with histamine (1 microM). RESULTS: PDE4 was the only isoenzyme activity increased in treated neutrophils. Kinetic analysis showed a approximately 1.5-fold increase in Vmax without alteration of Km values. cAMP content in treated cells was higher than resting values (0.52+/-0.07 vs. 2.75+/-0.31 pmol/10(6) cells). RT-PCR showed increased expression of mRNA transcripts for PDE4B in histamine-treated cells. Functionally, up-regulation of PDE4 reduced the inhibition by prostaglandin E2 of zymosan-induced superoxide generation. CONCLUSION: Histamine up-regulates PDE4 activity and produces heterologous desensitisation of human neutrophils.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2000

beta-Adrenoceptor stimulation up-regulates phosphodiesterase 4 activity and reduces prostaglandin E2-inhibitory effects in human neutrophils.

Human neutrophils were treated for 4 h with a combination of salbutamol (1 microM), a beta2-adrenoceptor agonist, and rolipram (30 microM), a selective phosphodiesterase 4 inhibitor, to investigate whether this treatment produces up-regulation of phosphodiesterase activity with functional consequences. Anion-exchange chromatography coupled with the use of selective activators and inhibitors demonstrated that a phosphodiesterase activity with characteristics of the isoenzyme type 4 was increased in drug-treated cells. Kinetic analysis showed a approximately 1.5-fold increase in Vmax without alteration of Km values. The augmented phosphodiesterase activity in drug-treated cells was abolished by actinomycin D. Cyclic AMP content in drug-treated cells was higher than resting values (27.28+/-2.79 pmol/10(6) cells vs. 0.34+/-0.03 pmol/10(6) cells). Reverse transcriptase-polymerase chain reaction showed increased expression of mRNA transcripts for PDE4B and PDE4A in drug-treated cells. Functionally, up-regulation of phosphodiesterase 4 reduced the inhibition by prostaglandin E2 of zymosan-induced superoxide generation.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1998

Effects of fenspiride on human bronchial cyclic nucleotide phosphodiesterase isoenzymes: functional and biochemical study.

We have investigated the role of human bronchial cyclic nucleotide phosphodiesterases in the effects of fenspiride, a drug endowed with bronchodilator and anti-inflammatory properties. Functional studies on human isolated bronchi showed that fenspiride (10(-6)-3 x 10(-3) M, 30 min) induced a shift to the left of the concentration-response curves for isoprenaline and sodium nitroprusside with -logEC50 values of 4.1+/-0.1 (n = 7) and 3.5+/-0.2 (n = 8), respectively. Biochemical studies were carried out on three human bronchi in which separation of cyclic nucleotide phosphodiesterase isoenzymes was performed by ion exchange chromatography followed by determination of phosphodiesterase activity with a radioisotopic method. Phosphodiesterase 4 (cyclic AMP-specific) and phosphodiesterase 5 (cyclic GMP-specific) were the major phosphodiesterase isoforms present in the human bronchial tissue. The presence of phosphodiesterase 1 (Ca2+/calmodulin-stimulated), phosphodiesterase 2 (cyclic GMP-stimulated) and, in two cases, phosphodiesterase 3 (cyclic GMP-inhibited) was also identified. Fenspiride inhibited phosphodiesterase 4 and phosphodiesterase 3 activities with -logIC50 values of 4.16+/-0.09 and 3.44+/-0.12, respectively. Phosphodiesterase 5 activity was also inhibited with a -logIC50 value of approximately 3.8. Fenspiride (< or = 10(-3) M) produced less than 25% inhibition of phosphodiesterase 1 and phosphodiesterase 2 activities. In conclusion, fenspiride is an effective inhibitor of both cyclic AMP and cyclic GMP hydrolytic activity in human bronchial tissues and this action may contribute to its airway effects.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1997

Halothane inhibits endothelium-dependent relaxation elicited by acetylcholine in human isolated pulmonary arteries.

This study examined whether a clinically relevant concentration of the volatile anaesthetic halothane modifies the endothelium-dependent relaxation produced by acetylcholine (3 nM-10 microM), histamine (1 pM-0.1 microM) and anti-human immunoglobulin E (1:1000) in human isolated pulmonary arteries submaximally precontracted with noradrenaline. An inhibitor of nitric oxide formation, N(G)-nitro-L-arginine (100 microM), attenuated acetylcholine-induced relaxation but failed to inhibit histamine- and anti-human immunoglobulin E-induced relaxation. Indomethacin (2.8 microM, a cyclooxygenase inhibitor) preferentially reduced the relaxation to histamine and anti-human IgE. Halothane (2%) significantly attenuated the relaxation to acetylcholine but had no significant effect on the relaxation elicited by histamine and anti-human IgE. Halothane (2%) enhanced the basal release of prostaglandin I2 by human pulmonary arteries (control 0.31 +/- 0.04 ng mg(-1); treated tissues 0.50 +/- 0.06 ng mg(-1); n = 5; P < 0.05). Halothane (2%) did not alter the responsiveness and sensitivity of preparations to relaxants acting through activation of adenylyl cyclase (forskolin) or guanylyl cyclase (sodium nitroprusside) or by the opening of K(ATP) channels (cromakalim). In conclusion, halothane inhibits the endothelium-dependent relaxation of human pulmonary arteries to acetylcholine by interfering with the nitric oxide pathway at a site before activation of soluble guanylyl cyclase in vascular smooth muscle.

Acetylcholine↗
PubMed1997

Inhibitory effects of N-acetylcysteine on superoxide anion generation in human polymorphonuclear leukocytes.

It has been suggested that reactive oxygen species released by activated polymorphonuclear leukocytes (PMN) in man is one mechanism of tissue injury. Therapeutic action aimed at increasing antioxidant defence mechanisms is still a clinical challenge. This study examines the activity of N-acetylcysteine, a known antioxidant, in the protection of PMN exposed in-vitro to the chemoattractant peptide fMet-Leu-Phe (FMLP), the protein kinase C activator phorbol myristate acetate or the lipid peroxidation promoter t-butyl hydroperoxide. FMLP (3-300 nM) and phorbol myristate acetate (160 pm-160 nM) induced concentration-related superoxide anion generation. Pre-treatment with N-acetylcysteine (33-333 microM) resulted in concentration-related inhibition of superoxide production induced by FMLP (30 nM) or phorbol myristate acetate (16 nM);-log IC50 values were 3.97 +/- 0.07 and 3.91 +/- 0.10, respectively. Changes in intracellular calcium ion concentration ([Ca2+]i) induced by FMLP (30 nM) were studied in fura-2-loaded human PMN. FMLP produced a transient calcium response, i.e. a peak followed by decay to a residual value above baseline. N-Acetylcysteine (333 microM) did not affect either basal [Ca2+]i values or changes in [Ca2+]i values after treatment with FMLP. Activation by phorbol myristate acetate caused a reduction in glutathione levels from 5.94 +/- 0.86 (control) to 1.84 +/- 0.51 nmol/3 x 10(6) cells (P < 0.05 compared with control). Pre-treatment with N-acetylcysteine (333 microM) fully reversed the reduction in glutathione levels induced by phorbol myristate acetate (4.83 +/- 0.68 nmol/3 x 10(6) cells; P > 0.05 compared with control). Exposure to t-butyl hydroperoxide (0.5 mM, 30 min) markedly increased malondialdehyde levels (from 0.03 +/- 0.02 to 0.73 +/- 0.07 nmol/10(6) cells), and index of lipid peroxidation. Malondialdehyde levels were significantly reduced in PMN treated with N-acetylcysteine (333 microM; 0.55 +/- 0.04 nmol/10(6) cells; P < 0.05 compared with untreated cells exposed to t-butyl hydroperoxide). In conclusion, N-acetylcysteine reduces superoxide generation in response to FMLP and phorbol myristate acetate and partially protects against lipid peroxidation in PMN from man. The protection afforded by N-acetylcysteine is not related to alteration of the intracellular calcium signal but might be effected by replenishment of the intracellular glutathione levels.

Acetylcysteine↗
PubMed1996

Effects of selective phosphodiesterase inhibitors on platelet-activating factor- and antigen-induced airway hyperreactivity, eosinophil accumulation, and microvascular leakage in guinea pigs.

There is currently interest in the potential use of selective inhibitors of cyclic nucleotide phosphodiesterases (PDE) in the treatment of asthma. In this study we examined the effects of three selective PDE inhibitors, milrinone (PDE III), rolipram (PDE IV) and zaprinast (PDE V), on the broncoconstriction produced by antigen and histamine, the airway hyperreactivity and microvascular leakage after aerosol exposure to platelet-activating factor (PAF) and antigen, and the antigen-induced eosinophil infiltration in guinea-pig lung. Inhaled rolipram (0.01-10 mg ml-1) inhibited dose dependently the bronchospasm produced by aerosol antigen (5 mg ml-1) an anaesthetised, ventilated guinea-pigs. Rolipram (10 mg ml-1) produced maximal inhibition of antigen-induced bronchoconstriction but only partial inhibition of the response to aerosol histamine (1 mg ml-1). Milrinone and zaprinast (each 10 mg ml-1) showed weak, or no, inhibitory effects against bronchoconstriction produced by aerosol antigen or histamine. Pretreatment with rolipram (10 mg kg-1, i.p.) prevented airway hyperreactivity to histamine which develops 24 h after exposure of conscious guinea-pigs to aerosol PAF (500 micrograms ml-1) or antigen (5 mg ml-1). The pulmonary eosinophil infiltration obtained with 24 h of antigen-exposure was inhibited by rolipram. In contrast, milrinone and zaprinast (each 10 mg kg-1, i.p.) failed to reduce either the airway hyperreactivity of the eosinophil accumulation in these animals. Rolipram (1-10 mg ml-1) reduced the extravasation of Evans blue after aerosol PAF (500 micrograms ml-1) at all airway levels while a lower dose (0.1 mg ml-1) was only effective at intrapulmonary airways. Rolipram (0.01-1 mg ml-1) markedly reduced airway extravasation produced by inhaled antigen (5 mg ml-1). Zaprinast (1-10 mg ml-1) was also effective against airway microvascular leakage produced by aerosol PAF or antigen while milrinone (10 mg ml-1) had no antiexudative effect. These data support previous suggestions that pharmacological inhibition of PDE IV results in anti-spasmogenic and anti-inflammatory effects in the airways and may be useful in the treatment of asthma.

Animals↗
PubMed1995

Antagonism of leukotriene responses in human airways by BAY x7195.

Contractions induced by leukotriene and anti-IgE (sheep antiserum to human IgE) were antagonized by pretreatment of human airways with the cysteinyl leukotriene receptor antagonist BAY x7195 ((4S)-[4-carboxyphenylthio]-7-[4-(4-phenoxybutoxy)-phenyl]-h ept-5-(z)- enoic acid). However, this receptor antagonist did not inhibit either leukotriene D4- or leukotriene C4-induced contractions in human pulmonary veins. The pA2 value for BAY x7195 in human airways against leukotriene D4 was 7.83 +/- 0.16 with a slope of 1.07 +/- 0.15 (means +/- S.E.M; n = 11). The IC50 value for BAY x7195 in human airways contracted with anti-IgE was 0.31 +/- 0.08 microM (n = 11). These results were comparable to those obtained with ICI 204,219 (4-(5-cyclopentyl-oxycarbonylamino-1-methylindol-3-ylmeth yl)-3-methoxy-N-otolyl - sulfonylbenzamide). These data demonstrate that BAY x7195 is a potent selective leukotriene receptor antagonist which may block allergic reactions in the lung.

Antibodies, Anti-Idiotypic↗
PubMed1995

Leukotriene receptors on human pulmonary vascular endothelium.

1. Cysteinyl-leukotrienes cause contractions and/or relaxations of human isolated pulmonary vascular preparations. Although, the localization and nature of the receptors through which these effects are mediated have not been fully characterized, some effects are indirect and not mediated via the well-described LT1 receptor. 2. In human pulmonary veins (HPV) with an intact endothelium, leukotriene D4 (LTD4) induced contraction above basal tone. This response was observed at lower concentrations of LTD4 in the presence of nitric oxide synthase inhibitor N omega-nitro-L-arginine (L-NOARG). Contractions (in the absence and presence of L-NOARG) were partially blocked by the LT1 antagonists (MK 571 and ICI 198615). 3. LTD4 relaxed HPV previously contracted with noradrenaline. This relaxation was potentiated by LT1 antagonists, but was abolished by removal of the endothelium. LTD4 also relaxed human pulmonary arteries (HPA) precontracted with noradrenaline but this effect was not modified by LT1 antagonists. 4. The results suggest that contraction of endothelium-intact HPV by LTD4 is partially mediated via LT1 receptors. Further, in endothelium-intact HPV, this contraction was opposed by a relaxation induced by LTD4, dependent on the release of nitric oxide, which was mediated, at least in part, via a non-LT1 receptor. In addition, LTD4 relaxation on contracted HPA was not mediated by LT1 receptors. 5. The mechanical effects of LTD4 on human pulmonary vasculature are complex and involve both direct and indirect mechanisms mediated via at least two types of cysteinyl-leukotriene receptors.

Analysis of Variance↗
PubMed1994

Effects of Ca2+ channel antagonists and benzodiazepine receptor ligands in normal and skinned rat urinary bladder.

The effects of Ca2+ channel antagonists and benzodiazepine receptor ligands against concentration-dependent contractions of rat urinary bladder induced by CaCl2 (0.1-50 mM, in K(+)-depolarized tissues), KCl (1-100 mM) and acetylcholine (0.1 microM to 1 mM) were studied. Nifedipine (0.001-0.1 microM), verapamil (0.01-1 microM), diltiazem (0.01-1 microM), cinnarizine (1-100 microM), and trifluoperazine (1-100 microM) each produced a concentration-related inhibition of the log concentration-effect curve for CaCl2. The rank order of potencies of these antagonists, measured as the IC50 against Ca2+ (25 mM)-induced contraction of depolarized bladder, was nifedipine (0.01 microM) > diltiazem (0.36 microM) approximately verapamil (0.41 microM) > or = cinnarizine (2.57 microM) > trifluoperazine (17.4 microM). These antagonists depressed KCl-induced contractions with an effectiveness and potency similar to that displayed against CaCl2-induced contractions. Nifedipine, verapamil, and diltiazem but not cinnarizine and trifluoperazine had a preferential inhibitory effect on the contractions elicited by KCl when compared to those elicited by acetylcholine. Ro 5-4864, diazepam, midazolam and the non-benzodiazepine PK 11195, each at 1-100 microM, depressed CaCl2- and KCl-induced contractions (IC50 values in the micromolar range). Benzodiazepines and PK 11195, all at 100 microM, markedly depressed acetylcholine-induced contractions. Flumazenil was scarcely effective. Cinnarizine (100 microM) and trifluoperazine (100 microM), but not the other Ca2+ channel antagonists and benzodiazepine receptor ligands tested, depressed Ca2+ (20 microM)-evoked contractions of skinned bladder. It is concluded that the action of nifedipine, verapamil, and diltiazem is restricted to the plasmalemma whereas cinnarizine and trifluoperazine also act on the intracellular contractile apparatus.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1993

Role of endothelium in the responses to noradrenaline in normal and sensitized guinea-pig aorta.

1. The pharmacological reactivity of sensitized blood vessels has been less studied than that of the airways. Aorta rings were obtained from normal (non-sensitized) and actively sensitized guinea-pigs, and prepared for isometric recording of tension changes. 2. Noradrenaline (10 nM-0.1 mM), histamine (0.1 microM-0.1 mM) and KCl (10-100 mM) produced concentration-related contractions of normal tissues. Removal of endothelium resulted in a marked leftward and upward shift of the concentration-response curve for noradrenaline but it did not alter histamine- or KCl-induced responses. Pretreatment with L-NG-nitroarginine (L-NOARG, 30 microM), haemoglobin (5 microM) or ibuprofen (10 microM) enhanced noradrenaline-induced responses without affecting those to histamine or KCl. 3. Removal of endothelium or pretreatment with L-NOARG or ibuprofen did not alter agonist-induced responses in sensitized tissues. Acetylcholine (1 microM)-induced relaxation of the contraction produced by noradrenaline (1 microM) in intact rings was diminished in sensitized compared to normal tissues. 4. Neuronal uptake and release of [3H]-noradrenaline did not differ in normal and sensitized tissues. 5. Loss of the modulatory role of endothelium and other mechanisms may be involved in the hyperreactivity of sensitized guinea-pig aorta.

Animals↗
PubMed1993

Relaxation by calcium antagonists of potassium-contracted trachea from normal and sensitized guinea-pigs: influence of epithelium and the surface of drug entry.

A technique by which drug access was restricted to either the mucosal or the adventitial surface of tracheal rings, isolated from normal (unsensitized) or sensitized guinea-pigs, was used to study the role of the epithelium in the relaxation produced by calcium antagonists (verapamil, nifedipine, cinnarizine and flunarizine) of K(+)-induced contraction. In trachea from normal guinea-pigs, the relaxation to verapamil for unrestricted or mucosal drug entry was reduced in the absence of epithelium, whereas the relaxation produced by nifedipine, cinnarizine or flunarizine was unchanged. In sensitized trachea, the relaxation elicited by the calcium antagonists tested was similar in intact and epithelium-denuded tracheal rings irrespective of the surface of drug entry. These results confirm that the epithelium influences the relaxation to verapamil. This modulatory effect is absent in sensitized trachea and is not shared by other calcium antagonists.

Animals↗
PubMed1993

Effects of cromakalim (BRL 34915) in trachea isolated from actively sensitized guinea-pigs.

The effects of cromakalim were examined in tracheal strips isolated from normal (unsensitized) guinea-pigs and from animals actively sensitized to bovine serum albumin. Sensitized tracheae exhibited hyper-responsiveness to KCl, acetylcholine and histamine. In normal and sensitized tracheae, cromakalim (0.01-10 microM) produced a concentration-related suppression of spontaneous tone. The ability of cromakalim to relax tracheal strips was reduced when tone was raised by KCl (25 mM), acetylcholine (0.1 mM) or histamine (0.1 mM) and lost against KCl (120 mM)-induced spasm. Procaine (5 mM) abolished the relaxant effect of cromakalim whilst tetraethylammonium (8 mM) was without effect. These effects were similar in normal and sensitized tissues. Cromakalim (10 microM) produced minor alterations of the concentration-effect curves of KCl (1-100 mM), acetylcholine (1 nM-1 mM) and histamine (1 nM-1 mM) in normal and sensitized tissues. The results from this pharmacomechanical study do not support the hypothesis that altered properties of cromakalim-sensitive K+ channels underlie the airway hyper-reactivity induced by active sensitization to bovine serum albumin.

Acetylcholine↗
PubMed1993

Rolipram inhibits airway microvascular leakage induced by platelet-activating factor, histamine and bradykinin in guinea-pigs.

Rolipram (0.1-1000 micrograms kg-1, i.v.) reduced the increase in microvascular permeability induced by platelet-activating factor (PAF; 50 ng kg-1, i.v.) at different sites of the guinea-pig airways. Rolipram (1-100 micrograms kg-1, i.v.) inhibited histamine (30 micrograms kg-1, i.v.)- and bradykinin (0.3 micrograms kg-1, i.v.)-induced airway microvascular leakage. These effects of rolipram were obtained at doses which inhibit histamine (7-20 micrograms kg-1 min-1)-induced bronchoconstriction (IC50 = 3 +/- 1 micrograms kg-1, i.v.) without depressing arterial blood pressure in the guinea-pig. Aminophylline (50 mg kg-1) did not change the effect of PAF. The anti-exudative effect of rolipram is of potential therapeutic value in asthma.

Aminophylline↗
PubMed1993

Contraction of bovine isolated bronchial airways: effects of epithelium removal.

The influence of the epithelium on the contractile responses of bovine bronchial rings to acetylcholine, carbachol, 5-hydroxytryptamine and histamine was studied. Epithelium removal caused a significant leftward shift of the acetylcholine concentration-effect curve, pD2 values were 2.86 +/- 0.11 and 3.34 +/- 0.18 for intact and rubbed tissue, respectively (P < 0.05). However, there was no change in the acetylcholine maximal response. The sensitivity and responsiveness of the bovine bronchus to the other spasmogens were not significantly altered by removal of the epithelium. These results suggest that the epithelium of bovine bronchi modulates only acetylcholine-induced contraction.

Acetylcholine↗
PubMed1993

Response to anti-human IgE in human pulmonary arteries. Regulation by endothelium.

Initial reports concerning anaphylactic reactions in the lung have demonstrated that histamine is released, and this mediator may be responsible for the severe hypotension observed in vivo in sensitized animals. However, those mechanisms involved in the antigen-vascular interactions have not been elucidated. Human isolated pulmonary arterial preparations relaxed when challenged with anti-human IgE (a-IgE). This response was associated with a release of histamine and PGI2. Both the relaxation and the release of PGI2 were attenuated by removal of the endothelium or by prior treatment of the tissues with chlorpheniramine. Indomethacin also significantly reduced the relaxations produced by a-IgE. In addition, L-NOARG in the presence of indomethacin blocked the a-IgE-dependent relaxation. Stimulation of these tissues with histamine also induced relaxations which were endothelium dependent and blocked by chlorpheniramine and L-NOARG in the presence of indomethacin. These results suggest that the relaxations via products of the cyclooxygenase and NO pathways were mediated by histamine release which stimulated the endothelium.

Arginine↗
PubMed1993

Differential effects of calcium channel antagonists in rat normal and skinned fundus.

CaCl2 (0.1-25 mM, in K(+)-depolarized tissues), KCl (10-112 mM) and acetylcholine (1 nM-1 mM) produced concentration-dependent contractions of rat isolated fundus. Nifedipine (0.01-500 mcM), diltiazem (0.01-100 mcM) and flunarizine (10-500 mcM) each produced a concentration-related inhibition of the log concentration-effect curve for CaCl2. The rank order of potencies of these antagonists, measured as the IC50 against Ca2+ (25 mM)-induced contraction of depolarized fundus, was nifedipine (1.9 mcM) = diltiazem (2.5 mcM) >> flunarizine (660 mcM). Diltiazem depressed KCl-induced contraction with an effectiveness and potency similar to that displayed against CaCl2 but nifedipine and flunarizine were less effective against contractions to KCl compared to CaCl2. Flunarizine (500 mc), but not the other antagonists tested, depressed Ca2+ (20 mc)-evoked contraction of skinned rat fundus preparations. It is concluded that distinct differences exist between the Ca2+ channel antagonists examined. The action of nifedipine and diltiazem is restricted to the plasmalemma, whereas flunarizine also acts on the intracellular contractile apparatus.

Acetylcholine↗
PubMed1992

Effects of Na+ transport inhibitors on guinea-pig tracheal responses to spasmogens.

The effects of ouabain, amiloride, K(+)-free solution and low Na+ (25 mM) solution on the responses to CaCl2 (in Ca(2+)-free, K(+)-depolarizing solution), KCl, acetylcholine, histamine and 5-hydroxytryptamine were studied in guinea-pig isolated trachea. Ouabain (10 microM) did not alter the contractile responses to CaCl2, KCl and acetylcholine but depressed those to histamine and 5-hydroxytryptamine produced in normal Ca2+ (2.5 mM) and Ca(2+)-free (EGTA 0.1 mM) media. Amiloride (0.1 mM), K(+)-free solution, and low Na+ solution depressed responses to acetylcholine, histamine and 5-hydroxytryptamine produced in normal Ca2+ and Ca(2+)-free media. Ouabain and amiloride had no effect on responses of skinned strips to Ca2+. The mechanism of the inhibitory effects of these interventions is uncertain but the findings suggest that the availability of Na+ influences the airway smooth muscle responses to spasmogens.

Acetylcholine↗