RESUMO
Furosemide attenuates airway obstruction in asthmatic subjects when administered as an aerosol pretreatment. This protective effect of furosemide could be related to relaxation of bronchial smooth muscle or to increased bronchial blood flow. To determine whether furosemide dilates bronchial smooth muscle, isometric contractile responses in distal bronchi from young pigs were studied. In bronchial smooth muscle rings that were precontracted with 10(-5) M acetylcholine, significant relaxation occurred with 10(-8) to 3 x 10(-6) M isoproterenol but not with 10(-8) to 10(-3) M furosemide. In contrast, bronchial arteries that were precontracted with either 10(-4) M norepinephrine or 10(-8) M vasopressin significantly relaxed in response to 10(-4) to 3 x 10(-3) M and 10(-3) to 3 x 10(-3) M furosemide, respectively. We conclude that furosemide, under the described experimental conditions, relaxes airway vascular smooth muscle but not bronchial smooth muscle. These results are consistent with previous suggestions that inhaled furosemide increases blood flow to airway tissues (Gilbert IA, Lenner KA, Nelson JA, Wolin AD, and Fouke JM. J Appl Physiol 76: 409-415, 1994).
Assuntos
Artérias/fisiologia , Brônquios/fisiologia , Furosemida/farmacologia , Músculo Liso Vascular/fisiologia , Músculo Liso/fisiologia , Animais , Artérias/efeitos dos fármacos , Brônquios/irrigação sanguínea , Brônquios/efeitos dos fármacos , Feminino , Técnicas In Vitro , Isoproterenol/farmacologia , Masculino , Músculo Liso/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , SuínosRESUMO
Tachykinin NK1 receptors are present on human pulmonary arteries. Addition of the specific tachykinin NK1 receptor agonist, [Met-OMe11]substance P produced a concentration-dependent relaxation (0.1 nM to 100 nM) in pulmonary arteries preconstricted with phenylephrine (30 microM). The EC50 (agonist concentration needed to produce 50% of the maximal relaxation) value for [Met-OMe11]substance P was 3.7+/-0.7 nM. The relaxation induced by [Met-OMe11]substance P was selectively inhibited by the tachykinin NK1 receptor antagonist CP 99994 (1 nM), with a pKb of 9.9+/-0.3. Treatment with the tachykinin NK2 receptor antagonist SR 48968 (100 nM) did not significantly affect the vasorelaxation due to [Met-OMe11]substance P (P > 0.05, one-way analysis of variance; ANOVA).
Assuntos
Artéria Pulmonar/fisiologia , Receptores da Neurocinina-1/fisiologia , Vasodilatação , Relação Dose-Resposta a Droga , Humanos , Fenilefrina/farmacologia , Piperidinas/farmacologia , Artéria Pulmonar/efeitos dos fármacos , Artéria Pulmonar/metabolismo , Receptores da Neurocinina-1/efeitos dos fármacos , Substância P/farmacologia , Vasoconstritores/farmacologia , Vasodilatação/efeitos dos fármacosRESUMO
The isolated perfused guinea pig lung was used to investigate the effect of nociceptin against bronchoconstriction elicited by endogenous and exogenous tachykinins. The opioid receptor-like 1 (ORL1) receptor agonist, nociceptin/orphanin FQ (0.001-1 microM) produced a dose-related inhibition of the capsaicin-induced bronchoconstriction (10(-5)-10(3) microg) in isolated guinea pig lung (P<0.05), a response mediated by the release of endogenous tachykinins from lung sensory nerves. The new ORL1 receptor antagonist 1-[(3R, 4R)-1-Cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1, 3-dihydro-2H-benzimidazol-2-one (J-113397) (0.3 microM) significantly blocked the inhibitory effect of nociceptin/orphanin FQ (0.01 microM) on capsaicin-induced bronchoconstriction, whereas the non-selective opioid receptor antagonist naloxone (1 microM) had no effect. Nociceptin/orphanin FQ (1 microM) did not affect the bronchoconstriction induced exogenously by the tachykinin NK2 receptor agonist neurokinin A. In conclusion, the present data provide evidence that nociceptin inhibits capsaicin-evoked tachykinin release from sensory nerve terminals in guinea pig lung by a prejunctional mechanism. This inhibitory action occurs independently from activation of opioid receptors. The present study also indicates that J-113397 is a potent ORL1 receptor antagonist.
Assuntos
Broncoconstrição/efeitos dos fármacos , Capsaicina/antagonistas & inibidores , Pulmão/efeitos dos fármacos , Antagonistas de Entorpecentes , Peptídeos Opioides/farmacologia , Receptores Opioides/agonistas , Animais , Benzimidazóis/farmacologia , Células CHO , Capsaicina/farmacologia , Cricetinae , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Cobaias , Técnicas In Vitro , Naloxona/farmacologia , Antagonistas de Entorpecentes/farmacologia , Piperidinas/farmacologia , Radioisótopos de Enxofre , Receptor de Nociceptina , NociceptinaRESUMO
The postjunctional alpha(2)-adrenoceptor-mediated contractility was characterized in human saphenous vein derived from coronary artery bypass graft surgery. Human saphenous vein contracted to alpha(2)-adrenoceptor selective agonists BHT-920 (5,6,7,8-Tetrahydro-6-(2-propenyl)-4H-thiazolo[4,5-d]azepin-2-amine dihydrochloride; pD(2)=6.7+/-0.1) and UK 14,304 (5-Bromo-6-(2-imidazolin-2-ylamino)quinoxaline; pD(2)=7.2+/-0.1). BHT-920-induced contractions were inhibited by the alpha(2)-adrenoceptor antagonist yohimbine (17-Hydroxy-yohimban-16-carboxylic acid methyl ester hydrochloride; pA(2)=8.7+/-0.5), but not by the alpha(1)-adrenoceptor antagonist prazosin (1-[4-Amino-6,7-dimethoxy-2-quinazolinyl]-4-[2-furanylcarbonyl]-piperazine hydrochloride; 300 nM). In contrast, prazosin (pK(b)=7.9+/-0.2) potently antagonized contractions elicited by the alpha(1)-adrenoceptor agonist phenylephrine ((R)-3-Hydroxy-alpha-[(methylamino)methyl] benzenemethanol hydrochloride; pD(2)=4.9+/-0.1), indicating that both alpha(2)- and alpha(1)-adrenoceptor evoke human saphenous vein contractions. Functional antagonist activity estimates (pA(2) or pK(b)) obtained for the alpha-adrenoceptor antagonists ARC 239 (2-[2-(4-(2-Methoxyphenyl)piperazin-1-yl)ethyl]-4,4-dimethyl-1,3-(2H,4H)-isoquinolindione dihydrochloride), WB 4101 (2-(2,6-Dimethoxyphenoxyethyl)aminomethyl-1,4-benzodioxane hydrochloride) and HV 723 (alpha-ethyl-3,4,5-trimethoxy-alpha-(3-((2-(2-methoxyphenoxy) ethyl)amino)propyl)benzeneacetonitrile) against BHT-920-induced human saphenous vein contractions were 7.0+/-0.6, 8.3+/-0.6 and 7.7+/-0.3, respectively. The alpha(2)-adrenoceptor subtype affinities (pK(i)) obtained in recombinant human alpha(2A)-, alpha(2B)- and alpha(2C)-adrenoceptor competition binding assays were 8.6, 8.3 and 8.6 for yohimbine; 6.3, 8.4 and 7.0 for ARC 239; 8.4, 7.5 and 8.4 for WB 4101 and 7.5, 7.4 and 7.9 for HV 723, respectively. Taken together, the binding and functional antagonist activity estimates obtained in these investigations indicate that alpha(2C)-adrenoceptor is the predominant postjunctional alpha(2)-adrenoceptor subtype in human saphenous vein.
Assuntos
Agonistas alfa-Adrenérgicos/farmacologia , Antagonistas Adrenérgicos alfa/farmacologia , Receptores Adrenérgicos alfa 2/efeitos dos fármacos , Veia Safena/efeitos dos fármacos , Vasoconstrição/efeitos dos fármacos , Idoso , Idoso de 80 Anos ou mais , Animais , Azepinas/farmacologia , Tartarato de Brimonidina , Células CHO , Cricetinae , Dioxanos/farmacologia , Relação Dose-Resposta a Droga , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Quinoxalinas/farmacologia , Receptores Adrenérgicos alfa 2/fisiologia , Veia Safena/fisiologia , Vasoconstrição/fisiologia , Ioimbina/farmacologiaRESUMO
In vivo studies were conducted in the guinea-pig to investigate the activity of the selective ORL1 receptor agonist nociceptin/orphanin FQ against capsaicin-induced bronchoconstriction, a response mediated by the release of tachykinins from pulmonary sensory nerves. Anesthetized guinea-pigs were ventilated with a rodent ventilator and placed in a whole-body plethysmograph, and pulmonary resistance (R(L)) and dynamic lung compliance (C(Dyn)) were monitored. Intravenous administration of nociceptin/orphanin FQ (0.3 mg/kg) inhibited the capsaicin-induced bronchoconstriction. The new nonpeptide ORL1 receptor antagonist 1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one (J-113397) administered intravenously (1 mg/kg) produced a significant blockade of the inhibitory effect of nociceptin/orphanin FQ (0.3 mg/kg) on capsaicin-induced bronchoconstriction, whereas the nonselective opioid receptor antagonist naloxone (1 mg/kg) had no effect. Nociceptin/orphanin FQ (0.3 mg/kg) did not affect the bronchoconstriction induced exogenously by the tachykinin NK2 receptor agonist [beta-ala8]-neurokinin A (4-10). We conclude that nociceptin inhibits in vivo capsaicin-evoked tachykinin release from sensory nerve terminals in the guinea-pig by a prejunctional mechanism. This inhibitory action does not involve activation of opioid receptors.
Assuntos
Broncoconstrição/efeitos dos fármacos , Broncoconstritores/farmacologia , Capsaicina/farmacologia , Peptídeos Opioides/uso terapêutico , Vasodilatadores/uso terapêutico , Animais , Benzimidazóis/administração & dosagem , Benzimidazóis/uso terapêutico , Quimioterapia Combinada , Cobaias , Injeções Intravenosas , Masculino , Naloxona/uso terapêutico , Neuropeptídeos/metabolismo , Peptídeos Opioides/administração & dosagem , Piperidinas/administração & dosagem , Piperidinas/uso terapêutico , Pletismografia Total , Inibidores de Proteases/uso terapêutico , Receptores Opioides/agonistas , Vasodilatadores/administração & dosagem , Receptor de Nociceptina , NociceptinaRESUMO
1. The present study compared the effect of the administration of tachykinin NK1- and NK2-receptor antagonists alone and in combination on exogenous and endogenous tachykinin-induced contractions using three different guinea-pig airway preparations: isolated bronchus, isolated perfused lung and in vivo. 2. In the isolated bronchi, the tachykinin NK1-receptor antagonist CP 99994 (0.01-1 microM) produced concentration-dependent inhibition of contractions induced the tachykinin NK1-receptor agonists substance P (SP) and [Met-OMe11] SP ([Met-OMe11]SP), whereas the tachykinin NK2-receptor antagonist SR 48968 (0.1 microM) had no effect. SR 48968 (0.001-0.01 microM) concentration-dependently inhibited contractions induced by the tachykinin NK2-receptor agonists neurokinin A (NKA) and [beta-Ala8]-neurokinin A (4-10) ([betaAla8]-NKA) whereas CP 99994 (0.1 microM) did not inhibit the contractions. The contractile activity of capsaicin, an agent that releases endogenous tachykinins from sensory C-fibres, was inhibited in a concentration dependent manner by SR 48968 (0.001-0.03 microM) but not by CP 99994 (0.1 microM). Combination of CP 99994 and SR 48968 caused increased inhibitory effects on the concentration-response curves to SP, [Met-OMe1l]SP, NKA, [beta-Ala8]-NKA and capsaicin. 3. In isolated perfused lungs, SR 48968 concentration (0.01-10 microM) dependently inhibited NKA-, [beta-Ala8]-NKA- and capsaicin-induced bronchoconstriction whereas CP 99994 (30 microM) had no effect on SP-, NKA-, [beta-Ala8]-NKA- and capsaicin-induced bronchoconstriction. Combination of inactive concentrations of CP 99994 and SR 48968 produced an increased inhibitory effect on all previous stimuli-induced bronchoconstriction. 4. In in vivo guinea-pig studies, intravenous and oral pretreatment with SR 48968 (0.01-1 mg kg(-1) i.v. and 0.1-3 mg kg(-1) p.o., respectively), but not with CP 99994 (1 mg kg(-1) i.v. and 0.3-30 mg kg(-1) p.o., respectively), produced a dose-dependent inhibition of the bronchoconstrictor responses induced by NKA, [beta-Ala8]-NKA and capsaicin. CP 99994 intravenously (0.3 mg kg(-1)) and orally (3-10 mg kg(-1)) inhibited SP-induced bronchoconstriction only. Intravenous and oral low dose combinations of CP 99994 and SR 48968 produced an increased inhibition of SP-, NKA-, [beta-Ala8]-NKA- and capsaicin-induced bronchoconstriction, respectively. The present data indicate that combined tachykinin NK1- and NK2-receptor antagonist treatment compared with single antagonist treatment, using CP 99994 and SR 48968, produced an augmented blockade of tachykinin NK1-, NK2- and capsaicin-mediated contractions in guinea pig airways. These findings support the hypothesis that a dual NK1- and NK2-receptor antagonist may provide an advantage over single activity tachykinin NK1- or NK2-receptor antagonists in pulmonary obstructive diseases.
Assuntos
Brônquios/efeitos dos fármacos , Broncoconstrição/efeitos dos fármacos , Antagonistas dos Receptores de Neurocinina-1 , Receptores da Neurocinina-2/antagonistas & inibidores , Animais , Benzamidas/farmacologia , Brônquios/fisiologia , Broncoconstrição/fisiologia , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Cobaias , Técnicas In Vitro , Pulmão/efeitos dos fármacos , Pulmão/fisiologia , Masculino , Contração Muscular/efeitos dos fármacos , Contração Muscular/fisiologia , Piperidinas/farmacologia , Receptores da Neurocinina-1/fisiologia , Receptores da Neurocinina-2/fisiologiaRESUMO
1. Pig nasal mucosal strips were incubated with alpha-adrenoceptor antagonists followed by alpha2-adrenoceptor agonist concentration-response curves. 2. Contractions elicited by the alpha2-adrenoceptor agonists BHT-920 (pD2 = 6.16 +/- 0.07), UK 14,304 (pD2 = 6.89 +/- 0.13) and PGE-6201204 (pD2 = 7.12 +/- 0.21) were blocked by the alpha2-adrenoceptor antagonist yohimbine (0.1 microm). In contrast, the alpha1-adrenoceptor antagonist prazosin (0.03 microm) had no effect on the BHT-920-, UK 14,304- and PGE-6201204-induced contractions, but blocked the contractile response to the alpha(1)-adrenoceptor agonist phenylephrine (pD2 = 5.38 +/- 0.04) and the mixed alpha1- and alpha2-adrenoceptor agonist oxymetazoline (pD(2) = 6.30 +/- 0.22). 3. The alpha2-adrenoceptor antagonist yohimbine (0.01-0.1 microm, pA2 = 8.04), alpha2B/C-adrenoceptor antagonist ARC 239 (10 microm, pK(b) = 6.33 +/- 0.21), alpha2A/C-adrenoceptor antagonist WB 4101 (0.3 microm, pK(b) = 8.01 +/- 0.24), alpha2A-adrenoceptor antagonists BRL44408 (0.1 microm, pK(b) = 6.82 +/- 0.34) and RX 821002 (0.1 microm, pKb = 8.31 +/- 0.35), alpha2C-adrenoceptor antagonists spiroxatrine (1 microm, pKb = 7.32 +/- 0.32), rauwolscine (0.1 microm, pKb = 8.16 +/- 0.14) and HV 723 (0.3 microm, pKb = 7.68 +/- 0.14) inhibited BHT-920-induced contractions in pig nasal mucosa. 4. The present antagonist potencies showed correlations with binding affinity estimates (pKi) obtained for these antagonists at the human recombinant alpha2A- and alpha2C-adrenoceptors (r = 0.78 and 0.83, respectively) and with binding affinity estimates (pKd) obtained in pig native alpha2A- and alpha2C-monoreceptor assays (r = 0.85 and 0.78, respectively). No correlation was observed for the alpha2B-subtype. 5. In conclusion, contractile responses to phenylephrine, BHT-920, UK 14,304, PGE-6201204 and oxymetazoline indicate that alpha1- and alpha2-adrenoceptors are present and mediate vasoconstriction in pig nasal mucosa. Furthermore, correlation analysis comparing antagonist potency in pig nasal mucosa with affinities for human recombinant alpha2-adrenoceptors and native pig alpha2-adrenoceptors suggest that alpha2A- and alpha2C-adrenoceptor subtypes constrict pig nasal mucosa vasculature.
Assuntos
Antagonistas de Receptores Adrenérgicos alfa 2 , Antagonistas Adrenérgicos alfa/metabolismo , Mucosa Nasal/metabolismo , Receptores Adrenérgicos alfa 2/metabolismo , Antagonistas Adrenérgicos alfa/farmacologia , Animais , Células CHO , Cricetinae , Relação Dose-Resposta a Droga , Feminino , Humanos , Técnicas In Vitro , Masculino , Mucosa Nasal/efeitos dos fármacos , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/fisiologia , SuínosRESUMO
In vivo anesthetized guinea pigs were used to investigate the effect of tachykinin NK1- and NK2-receptor antagonists, as a single dose or in combination, against hyperventilation-induced bronchoconstriction (HIB). Guinea pigs were ventilated with a rodent ventilator and placed in a whole-body plethysmograph. Hyperventilation was induced by increasing the respiratory rate from 50 to 185 breaths/min for 10 min that produced a 177+/-45% increase in pulmonary resistance (RL) and a 68+/-7% decrease in lung compliance (CDyn). Intravenous (0.03-0.3mg/kg) and oral (0.3-10mg/kg) pretreatments with the tachykinin NK2-antagonist SR 48968 produced a dose-dependent inhibition of HIB whereas pretreatments with the tachykinin NK1-antagonist CP 99994 (1mg/kg intravenously and 30 mg/kg orally) had no effect on HIB. Intravenous and oral combinations of inactive and low doses of CP 99994 and SR 48968 produced a greater inhibition of HIB than SR 48968 alone. Also, the tachykinin NK3-antagonist SB 223412 (1-3mg/kg intravenously and 30 mg/kg orally) did not significantly reduce HIB although a trend was observed at the highest dose tested intravenously (3mg/kg). We conclude that HIB in the guinea pig is mostly mediated by the tachykinin NK2-receptors and to a lesser extent by the tachykinin NK1-receptors. Because the hyperventilation response in guinea pigs may be a surrogate for exercise-induced obstructive airway disease in human, these results suggest that combined use of dual tachykinin NK1- and NK2-receptor antagonists may provide greater benefit than treatment with single activity tachykinin NK-receptor antagonist.
Assuntos
Benzamidas/farmacologia , Broncoconstrição/efeitos dos fármacos , Hiperventilação/complicações , Antagonistas dos Receptores de Neurocinina-1 , Piperidinas/farmacologia , Receptores da Neurocinina-2/antagonistas & inibidores , Administração Oral , Animais , Benzamidas/administração & dosagem , Relação Dose-Resposta a Droga , Interações Medicamentosas , Cobaias , Injeções Intravenosas , Masculino , Piperidinas/administração & dosagem , Quinolinas/farmacologia , Receptores da Neurocinina-3/antagonistas & inibidores , Testes de Função RespiratóriaRESUMO
The vascular bed in nasal mucosa of different species, including human, is highly vascularized and an extensive sinusoidal network of large capacitance vessels is present deep within the submucosa. When this network of venous sinusoids is engorged with blood, the swollen mucosa reduces the size of the airway lumen and congestion ensues. Nasal vasculature tone is strongly influenced by the sympathetic nervous system and the only drugs approved specifically to relieve vascular nasal obstruction are alpha-adrenoceptor sympathomimetic agents. Due to their vasoconstrictor action, the sympathomimetic decongestants oppose vasodilation, reducing nasal airway resistance and thus facilitating nose breathing. However, standard decongestants that are non-selective alpha-adrenoceptor agonists are associated with the potential for side-effect liabilities including hypertension, stroke, insomnia and nervousness. We propose than a selective alpha 2-adrenoceptor agonist, by acting preferentially on nasal venous capacitance vessels, will elicit decongestion with a reduced side-effect liability. In the present study, we evaluated the effects of the selective alpha 2-adrenoceptor agonist BHT-920 in a real-time tissue contractility assay using isolated pig nasal explants and in an in vivo cat model of congestion. The vasoconstrictor and decongestant effects of BHT-920 were compared to the non-selective alpha-adrenoceptor agonist epinephrine and the standard decongestant oxymetazoline. Our results showed that the alpha 2-adrenoceptor agonist BHT-920 preferentially contracts venous sinusoids confirming previous observations [Corboz MR, Varty LM, Rivelli MA, Mutter JC, Mingo G, McLeod R, et al. Effects of an alpha 2-adrenoceptor agonist in nasal mucosa. Arch Physiol Biochem 2003;11: 335-6, Corboz MR, Rivelli MA, Varty LM, Mutter J, Cartwright M, Rizzo CA, et al. Pharmacological characterization of postjunctional alpha-adrenoceptor in human nasal mucosa. Am J Rhinol 2005;19: 495-502] and displays decongestion without affecting blood pressure. Therefore, an alpha 2-adrenoceptor agonist, by causing constriction in the capacitance vessels of nasal mucosa, can produce nasal decongestion without the effects on blood pressure observed with the standard selective alpha 1-adrenoceptor and non-selective alpha-adrenoceptor sympathomimetic decongestants.
Assuntos
Agonistas de Receptores Adrenérgicos alfa 2 , Agonistas alfa-Adrenérgicos/farmacologia , Descongestionantes Nasais , Administração Tópica , Animais , Azepinas/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Gatos , Relação Dose-Resposta a Droga , Epinefrina/farmacologia , Feminino , Masculino , Contração Muscular/fisiologia , Mucosa Nasal/inervação , Mucosa Nasal/fisiologia , Oximetazolina/farmacologia , Receptores Adrenérgicos alfa 2 , Suínos , p-Metoxi-N-metilfenetilamina/farmacologiaRESUMO
Nasal congestion, one of the major disease features of rhinitis, is induced by the filling of venous sinusoids causing mucosal engorgement with resultant obstruction of nasal airflow. The only available drugs that directly target the underlying vascular features driving nasal obstruction are the sympathomimetic alpha-adrenoceptor agonists due to their vasoconstrictor action. However, standard decongestants are nonselective alpha-adrenoceptor agonists, which have the potential for side-effects liabilities such as hypertension, stroke, insomnia and nervousness. In the present study, the effects of nonsubtype selective alpha(2)-adrenoceptor agonists BHT-920 and PGE-6201204 were evaluated in several isolated nasal mucosa contractile bioassays including dog, pig and monkey, and in a real-time tissue contractility assay using isolated pig nasal explants for BHT-920. The decongestant activity of PGE-6201204 was evaluated in vivo in a cat model of experimental congestion. Our results showed that alpha(2)-adrenoceptor agonists (1) contract nasal mucosa of different species, (2) exert a preferential vasoconstrictor effect on the capacitance vessels (veins and sinusoids), and (3) elicit decongestion. In conclusion, a selective alpha(2)-adrenoceptor agonist causing constriction preferentially in the large venous sinusoids and veins of nasal mucosa and producing nasal decongestion is expected to show efficacy in the treatment of nasal congestion without the characteristic arterio-constrictor action of the standard nonselective sympathomimetic decongestants.
Assuntos
Agonistas de Receptores Adrenérgicos alfa 2 , Agonistas alfa-Adrenérgicos/farmacologia , Descongestionantes Nasais/farmacologia , Mucosa Nasal/efeitos dos fármacos , Antagonistas de Receptores Adrenérgicos alfa 2 , Agonistas alfa-Adrenérgicos/administração & dosagem , Antagonistas Adrenérgicos alfa/farmacologia , Animais , Azepinas/farmacologia , Gatos , Cães , Relação Dose-Resposta a Droga , Epinefrina/farmacologia , Feminino , Técnicas In Vitro , Macaca fascicularis , Macaca mulatta , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/fisiologia , Descongestionantes Nasais/administração & dosagem , Mucosa Nasal/irrigação sanguínea , Mucosa Nasal/fisiologia , Prazosina/farmacologia , Suínos , Porco Miniatura , Vasoconstrição/efeitos dos fármacos , Ioimbina/farmacologia , p-Metoxi-N-metilfenetilamina/farmacologiaRESUMO
The present study was undertaken to identify and determine the mechanism of noncholinergic pathways for the induction of liquid secretion across airway epithelium. Excised porcine bronchi secreted substantial and significant quantities of liquid when exposed to acetylcholine, substance P, or forskolin but not to isoproterenol, norepinephrine, or phenylephrine. Bumetanide, an inhibitor of Na(+)-K(+)-2Cl(-) cotransport, reduced the liquid secretion response to substance P by 69%. Approximately two-thirds of bumetanide-insensitive liquid secretion was blocked by dimethylamiloride (DMA), a Na(+)/H(+) exchange inhibitor. Substance P responses were preserved in airways after surface epithelium removal, suggesting that secreted liquid originated from submucosal glands. The anion channel blockers diphenylamine-2-carboxylate (DPC) and 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) inhibited >90% of substance P-induced liquid secretion, whereas DIDS had no effect. DMA, DPC, and NPPB had greater inhibitory effects on net HCO(3)(-) secretion than on liquid secretion. Although preserved relative to liquid secretion, net HCO(3)(-) secretion was reduced by 39% in the presence of bumetanide. We conclude that substance P induces liquid secretion from bronchial submucosal glands of pigs through active transport of Cl(-) and HCO(3)(-). The pattern of responses to secretion agonists and antagonists suggests that the cystic fibrosis transmembrane conductance regulator mediates this process.
Assuntos
Líquidos Corporais/metabolismo , Brônquios/efeitos dos fármacos , Brônquios/metabolismo , Substância P/farmacologia , Animais , Bicarbonatos/metabolismo , Bloqueadores dos Canais de Cálcio/farmacologia , Epitélio/efeitos dos fármacos , Epitélio/metabolismo , Técnicas In Vitro , Nitrobenzoatos/farmacologia , Concentração Osmolar , Valores de Referência , Suínos , ortoaminobenzoatos/farmacologiaRESUMO
In porcine bronchi, inhibition of both Cl- and HCO3- transport is required to block the anion secretion response to ACh and to cause mucus accumulation within ACh-treated submucosal gland ducts [S. K. Inglis, M. R. Corboz, A. E. Taylor, and S. T. Ballard. Am. J. Physiol. 272 (Lung Cell. Mol. Physiol. 16): L372-L377, 1997]. In this previous study, a combination of three potential HCO3- transport inhibitors [1 mM acetazolamide, 1 mM DIDS, and 0.1 mM dimethylamiloride (DMA)] was used to block carbonic anhydrase, Cl-/HCO3- exchange, and Na+/H+ exchange, respectively. The aim of the present study was to obtain a better understanding of the mechanism of ACh-induced HCO3- secretion in airway glands by determining which of the three inhibitors, in combination with bumetanide, is required to block anion secretion and so cause ductal mucin accumulation. Gland duct mucin content was measured in distal bronchi isolated from domestic pigs. Addition of either bumetanide alone, bumetanide plus acetazolamide, or bumetanide plus DIDS had no significant effect on ACh-induced mean gland duct mucin content. In contrast, glands treated with bumetanide plus DMA as well as glands treated with all four anion transport blockers were almost completely occluded with mucin after the addition of ACh. These data suggest that mucin is cleared from the ducts of bronchial submucosal glands by liquid generated from Cl(-)- and DMA-sensitive HCO3- transport.
Assuntos
Ânions/antagonistas & inibidores , Brônquios/metabolismo , Mucinas/metabolismo , Ácido 4,4'-Di-Isotiocianoestilbeno-2,2'-Dissulfônico/farmacologia , Acetazolamida/farmacologia , Acetilcolina/farmacologia , Animais , Bicarbonatos/antagonistas & inibidores , Bicarbonatos/metabolismo , Brônquios/efeitos dos fármacos , Bumetanida/farmacologia , Combinação de Medicamentos , Mucosa/efeitos dos fármacos , Mucosa/metabolismo , SuínosRESUMO
Furosemide pretreatment greatly reduces the severity of an asthmatic response to several types of bronchoconstrictor challenge. Indirect evidence suggests that furosemide exerts its protective effects by dilating the airway vasculature during thermal stress. To test the hypothesis that furosemide dilates airway microvessels, the tracheas of anesthetized rats were surgically exposed and continuously suffused with Krebs Ringer bicarbonate warmed to 37 degrees C. Tracheal adventitial arterioles (13.0 to 41.0 microns initial diameter, n = 47) and venules (50.0 to 99.0 microns initial diameter, n = 46) were visualized with a videomicroscope, and vessel diameters were measured using videocalipers. When vessels were preconstricted with 10(-4) M phenylephrine, a selective alpha 1-adrenergic agonist, and then treated with 10(-4) M furosemide, significant (p < 0.05) dilation was observed in both arterioles (from 64.6 to 79.5% of their initial diameter) and venules (from 52.1 to 65.4% of their initial diameter). When vessels were preconstricted with 10(-4) phenylephrine, after pretreatment with the cyclooxygenase inhibitor indomethacin (5.0 mg/kg), 10(-4) M furosemide significantly dilated arterioles (from 77.5 to 93.0% of their initial diameter) and venules (from 58.5 to 80.1% of their initial diameter). In vessels preconstricted with 10(-3) M L-NAME, an inhibitor of nitric oxide synthesis, addition of 10(-4) M furosemide to the suffusion still caused significant dilation in arterioles, from 77.4 to 88.8% of their initial diameter, and in venules from 79.5 to 86.7% of their initial diameter. These data confirm that furosemide, when applied topically, dilates tracheal arterioles and venules by cyclooxygenase- and nitric oxide-independent mechanisms.
Assuntos
Furosemida/farmacologia , Traqueia/irrigação sanguínea , Traqueia/efeitos dos fármacos , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologia , Animais , Arteríolas/efeitos dos fármacos , Arteríolas/fisiologia , Inibidores de Ciclo-Oxigenase/farmacologia , Inibidores Enzimáticos/farmacologia , Indometacina/farmacologia , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico Sintase/antagonistas & inibidores , Fenilefrina/farmacologia , Ratos , Ratos Sprague-Dawley , Fatores de Tempo , Vasoconstritores/farmacologia , Vasodilatação/fisiologia , Vênulas/efeitos dos fármacos , Vênulas/fisiologiaRESUMO
Airway submucosal glands secrete both macromolecules and liquid, yet the mechanisms by which these substances are secreted are not well understood. In this study, a video microscope was used to directly visualize the submucosal glands in isolated porcine distal bronchi and to observe their responses to acetylcholine (ACh), a glandular secretagogue. Submucosal glands were classified as either "antral," "linear," or "convoluted" glands based on the morphology of their terminal collecting ducts. Because antral duct glands were most easily visualized, the response to ACh was studied in detail in this gland type. Within 5-10 s after addition of 10 microM ACh, the cross-sectional area of the gland duct openings to the airway surface increased severalfold but returned to pre-ACh dimensions within 1 min. Between 30 s and 10 min after ACh addition, spherical particles (1-10 microm) entered the antral ducts from distal acini and exited through the duct openings to the airway surface. Some of the particles were retained within the antral duct where they were kept in constant motion by the action of cilia present within the antral duct. The particles, which are likely to contain the macromolecular secretory products of mucous and/or serous cells, maintained their spherical shape within the gland duct, suggesting that the secretion product was membrane bound. To our knowledge, these studies provide the first description of airway submucosal gland secretion as viewed in situ.
Assuntos
Acetilcolina/farmacologia , Brônquios/efeitos dos fármacos , Brônquios/metabolismo , Plexo Submucoso/efeitos dos fármacos , Plexo Submucoso/metabolismo , Animais , Brônquios/anatomia & histologia , Fluoresceína-5-Isotiocianato/análogos & derivados , Corantes Fluorescentes , Técnicas In Vitro , Soroalbumina Bovina , Plexo Submucoso/anatomia & histologia , SuínosRESUMO
To model the airway glandular defect in cystic fibrosis (CF), the effect of anion secretion blockers on submucosal gland mucus secretion was investigated. Porcine distal bronchi were isolated, pretreated with a Cl- secretion blocker (bumetanide) and/or a combination of blockers to inhibit HCO3- secretion (dimethylamiloride, acetazolamide, and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid), and then treated with acetylcholine (ACh), a glandular liquid and mucus secretagogue. Bronchi were then fixed, sectioned, and stained for mucins. Each gland duct was ranked for mucin content from zero (no mucin) to five (duct completely occluded with mucin). Untreated bronchi, bronchi treated only with ACh, and ACh-treated bronchi that received either bumetanide or the HCO3- secretion blockers all exhibited low gland duct mucin content (1.18 +/- 0.34, 0.59 +/- 0.07, 0.65 +/- 0.03, and 0.83 +/- 0.11, respectively). However, pretreatment with both Cl- and HCO3- secretion blockers before ACh addition resulted in substantial and significant ductal mucus accumulation (3.57 +/- 0.22). In situ videomicroscopy studies of intact airways confirmed these results. Thus inhibition of the anion (and presumably liquid) secretion response to ACh leads to mucus obstruction of submucosal gland ducts that resembles the early pathological changes observed in CF.
Assuntos
Ânions/antagonistas & inibidores , Brônquios/metabolismo , Muco/metabolismo , Acetilcolina/farmacologia , Animais , Ânions/metabolismo , Transporte Biológico , Brônquios/efeitos dos fármacos , Técnicas In Vitro , Microscopia de Vídeo , Mucinas/metabolismo , Mucosa/efeitos dos fármacos , Mucosa/metabolismo , SuínosRESUMO
Distal airways comprise the vast majority of total human airway surface area, yet little is known about transepithelial ion transport in these tissues. Pathways that regulate ion transport in porcine small bronchi (3.62 +/- 0.04 mm outer diameter) were studied by measuring the effects of secretogogues that stimulate Cl- secretion in proximal airways. Resting potential difference (PD), shortcircuit current (ISC), and resistance (Rt) across the distal bronchi were 3.4 +/- 0.1 mV (lumen negative), 40.8 +/- 1.7 microA/cm2, and 92.1 +/- 5.0 omega.cm2, respectively. Isoproterenol (10 microM), acetylcholine (ACh; 10 microM), or ATP (100 microM) induced immediate significant (P < 0.05) increases in PD and ISC. The Ca2+ ionophore A23187 (1 microM) induced a slow increase in PD that was accompanied by a significant 2.4-fold increase in Rt and no change in ISC. The responses to isoproterenol, ACh, and ATP were maintained in the presence of 10 microM amiloride. Pretreatment with 10 microM bumetanide to block Cl- secretion inhibited responses to isoproterenol and ATP but not to ACh. The ACh effect was inhibited only after both Cl- and HCO3- secretion were blocked. These data suggest that isoproterenol, ACh, and ATP stimulate anion secretion. Isoproterenol and ATP specifically stimulate Cl- secretion, whereas ACh can stimulate both Cl- and HCO3- secretion. A23187 has no effect on active transepithelial ion transport but increases barrier resistance in intact distal bronchial epithelium.
Assuntos
Brônquios/metabolismo , Absorção , Acetilcolina/farmacologia , Trifosfato de Adenosina/farmacologia , Animais , Bicarbonatos/metabolismo , Transporte Biológico , Brônquios/efeitos dos fármacos , Calcimicina/farmacologia , Cloretos/metabolismo , Íons , Isoproterenol/farmacologia , Sódio/farmacocinética , Estimulação Química , SuínosRESUMO
Previous study of adrenergic control of the tracheal vasculature in rats (1) demonstrated that beta-adrenergic blockade heightened arteriolar and large venular contractile responses to norepinephrine, a nonselective alpha-adrenergic agonist. The present study was undertaken to confirm the presence of functional beta-adrenergic receptors and to determine which beta-adrenergic receptor subtypes mediate vasodilation in this tissue. Tracheal adventitial arterioles (12.0 to 47.0 micro m initial diameter, n=39) and venules (48.0 to 98.5 micrometers initial diameter, n=44) were observed through a video microscope, and vessel diameters were measured. Vessels were preconstricted with 10(-4) M phenylephrine (PHE), a selective alpha 1-adrenergic agonist, to achieve sufficient tone for measurement of dilation responses. When vessels were treated only with PHE, arterioles and venules constricted to 55.9% and 67.6% of their initial diameter, respectively, after 15 min of suffusion. When preconstricted vessels were treated with the nonselective beta-adrenergic agonist isoproterenol (10(-5) M), both arterioles and venules significantly dilated from 63.4% to 82.9% and from 71.5% to 81.3% of their initial diameters. At high concentration (10(-5) M), the putative beta 2-adrenergic agonist terbutaline also caused preconstricted arterioles and venules to significantly dilate from 70.8% to 79.8% and from 71.5% to 83.4% of their initial diameters. The selective beta 1-adrenergic antagonist atenolol (10(-6) M) did not affect terbutaline-induced dilation in preconstricted arterioles, but greatly attenuated dilation in preconstricted venules. From these data, we conclude that beta 2-adrenergic receptors are present in and mediate dilation of tracheal arterioles, and also, that the dilation in large tracheal venules is mediated in large part through beta 1-adrenergic receptors.
Assuntos
Agonistas Adrenérgicos beta/farmacologia , Receptores Adrenérgicos beta/efeitos dos fármacos , Traqueia/irrigação sanguínea , Vasodilatadores/farmacologia , Agonistas alfa-Adrenérgicos/farmacologia , Antagonistas Adrenérgicos beta/farmacologia , Animais , Arteríolas/efeitos dos fármacos , Atenolol/farmacologia , Isoproterenol/farmacologia , Masculino , Microcirculação/efeitos dos fármacos , Fenilefrina/farmacologia , Ratos , Ratos Sprague-Dawley , Terbutalina/farmacologia , Traqueia/efeitos dos fármacos , Vasoconstritores/farmacologia , Vasodilatação , Vênulas/efeitos dos fármacos , Gravação em VídeoRESUMO
Although blood flow to the pulmonary airways is known to be largely under sympathetic control, virtually nothing is known about adrenergic regulation of vascular segments within the airway microcirculation. To evaluate the distribution of functional adrenergic receptor subtypes in the microvessels of the large airways, the change in diameter of adventitial vessels in rat trachea was measured following suffusion with selective and nonselective receptor agonists and antagonists. Microvessels were viewed with a video microscope, and vessel diameters were measured using video calipers. Arterioles (11.0 to 40.0 microns, n = 32), small postcapillary venules (11.0 to 26.0 microns, n = 16), medium venules (28.0 to 59.5 microns, n = 40), and large collecting venules (61.0 to 99.0 microns, n = 42) were distinguished. Similar sensitivities to norepinephrine (NE), a mixed alpha 1 and alpha 2 agonist, were observed in arterioles and medium venules with EC50 (agonist concentration needed to produce 50% of the maximal response) for contraction of 2.4 x 10(-7) and 3.3 x 10(-7) M, respectively. Large venules (EC50 of 1.6 x 10(-6) M) were significantly (p < 0.05) less sensitive than arterioles to NE. In the presence of propranolol, a beta receptor antagonist, the EC50 values for NE were not different between the three vessel groups, although the response to low doses of NE was significantly increased in arterioles. When vessels were treated with propranolol and phenylephrine, a selective alpha 1 agonist, arterioles (EC50 of 4.1 x 10(-7) M) were significantly more sensitive than large venules (EC50 of 4.9 x 10(-6) M).(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Receptores Adrenérgicos/análise , Traqueia/irrigação sanguínea , Animais , Relação Dose-Resposta a Droga , Técnicas In Vitro , Masculino , Microcirculação/metabolismo , Norepinefrina/farmacologia , Fenilefrina/farmacologia , Propranolol/farmacologia , Ratos , Ratos Sprague-Dawley , Vasoconstrição/efeitos dos fármacosRESUMO
We previously demonstrated that rat tracheal arterioles and large venules constrict in response to alpha-adrenergic agonists and dilate in response to beta-adrenergic agonists. To further investigate the vasodilatory mechanisms in these vessels, we hypothesized that the vascular tone in the tracheal microcirculation is regulated in part by endogenously released nitric oxide (NO). To test this hypothesis, rat tracheal microvessels were visualized in vivo with a video microscope. The change in diameter af adventitial arteriolar (14.5 to 42.0 microm initial diameter, n = 41) and large venular (50.0 to 100.0 microm initial diameter, n = 41) microvessels following the suffusion of vasoactive drugs was measured with video calipers. Significant constriction was observed in arterioles (to 70.0% of initial diameter) and large venules (to 76.6% of initial diameter) after 20 min of suffusion with L-NAME, an inhibitor of NO synthesis. This constriction was in large part reversed by L-arginine, a biochemical precursor of NO, in arterioles (to 93.2% of initial diameter) and in venules (to 90.8% of initial diameter). The combination of prazosin, a selective alpha1-adrenergic antagonist, and yohimbine, a selective alpha2-adrenergic antagonist, also reduced L-NAME-induced constriction in arterioles (to 87.9% of initial diameter) and in venules (to 85.2% of initial diameter). L-arginine or the combination of prazosin and yohimbine alone did not affect the diameter of tracheal microvessels. These data suggest that NO exerts an important influence on tracheal microvascular tone in rats, and may attenuate alpha-adrenergic constriction in these vessels.