neurokinin-a and Bronchial-Spasm

Neuropeptides and purines are possible autonomic neurotransmitters. Both tachykinins (neurokinin A, substance P) and adenosine cause acute airway narrowing by synergistic activation of airway mast cells and postganglionic vagal nerve endings.

Topics: Adenosine; Animals; Bronchi; Bronchial Spasm; Histamine Release; Mast Cells; Neurokinin A; Neurotransmitter Agents; Rats

Airway hyperresponsiveness to neurokinin A (NKA) occurs in inflammatory airway diseases like asthma. In this study, bronchoconstrictor reactivity to NKA was measured in beagle dogs neonatally sensitized to and challenged with ragweed. Comparisons were made to histamine and methacholine. Lung resistance (R(L)) and dynamic lung compliance (C(Dyn)) were measured in anesthetized, spontaneously breathing dogs before and after aerosol challenge with NKA, histamine or methacholine. The concentration of these agents increasing R(L)by 25% above baseline (PC(25)) was calculated before and 24 h after aerosolized ragweed challenge. Before ragweed, the bronchoconstrictor reactivity to NKA was four-fold higher in ragweed-sensitized dogs (PC(25)=0.036+/-0.006%) compared to non-sensitized controls (PC(25)=0.177+/-0.030%, P<0.05). On the other hand, there was no difference in the bronchoconstrictor reactivity to histamine or methacholine between these two groups. Twenty-four hours after ragweed challenge to sensitized dogs, NKA reactivity was unchanged from pre-ragweed values but histamine and methacholine reactivity was increased by 2-3-fold. These results demonstrate airway hyperresponsiveness to NKA, histamine and methacholine in allergic beagle dogs although hyperresponsiveness to NKA exists in these allergic dogs before an antigen challenge. This animal model may prove to be useful to evaluate the role of tachykinins in hyperractive airway diseases.

Topics: Administration, Inhalation; Aerosols; Animals; Bronchial Hyperreactivity; Bronchial Spasm; Bronchoconstriction; Dogs; Female; Histamine; Hypersensitivity; Male; Methacholine Chloride; Neurokinin A

1. The antibronchospastic activity against acetylcholine, capsaicin, electrical vagal stimulation and the selective tachykinin agonists ([beta Ala8]NKA-(4-10) and [Sar9]SP sulfone) of a novel NK2 receptor antagonist, MEN10,627 and/or the known NK1 receptor antagonist (+/-)-CP96,345 was studied in anaesthetized guinea-pigs. 2. MEN10,627 (0.1 mumol kg-1 i.v.) and (+/-)-CP96,345 (3 mumol kg-1 i.v.) selectively reduced the bronchospasm induced by NK2 and NK1 tachykinin receptor agonists, respectively, without affecting the other tachykinin receptor agonist- or acetylcholine-induced bronchospastic response. 3. MEN10,627 (0.1 mumol kg-1 i.v.), in a dose-dependent manner, reduced the non-cholinergic response induced by bilateral stimulation of the vagi or by intravenous capsaicin. 4. The administration of (+/-)-CP96,345 (3 mumol kg-1 i.v.) alone did not affect these responses but, when administered in association with the NK2 antagonist, (+/-)-CP96,345, was able to potentiate its inhibitory effect. 5. It is concluded that both NK1 and NK2 receptors are involved in the non-cholinergic bronchoconstriction induced by capsaicin or by stimulation of the vagi, although the NK2 receptor contribution is prominent.

Topics: Animals; Biphenyl Compounds; Bronchial Spasm; Capsaicin; Electric Stimulation; Guinea Pigs; Insufflation; Male; Neurokinin A; Neurokinin-1 Receptor Antagonists; Peptide Fragments; Peptides, Cyclic; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Substance P; Vagus Nerve

In a guinea-pig model of asthma, active immunization against substance P (SP) prevented the development of airways' hyperresponsiveness and reduced bronchospastic responses to SP (i.v.). The rat-mouse heterohybridoma NC1/34 secretes a specific, rat IgG1, anti-substance P antibody (alpha-SP Ab) which was isolated and purified by passing supernatant from cultures through thiophilic gel. Purity of antibody was about 50% (SDS-PAGE). The relative affinities of the alpha-SP Ab for SP, neurokinin A (NKA) and calcitonin gene-related peptide (CGRP) were estimated by ELISA using a constant amount of SP coupled (glutaraldehyde) to bovine serum albumin (BSA) to capture the antibody, alone and in the presence of increasing concentrations of the neuropeptides. At alpha-SP Ab dilutions of 1 in 5,000 to 1 in 32,000, CGRP did not prevent antibody binding to SP-BSA conjugate bound to the plates, but both SP and NKA prevented binding. In this system, the relative affinity of the alpha-SP Ab, at dilutions of 1 in 5,000 and 1 in 10,000, was about 50 times greater for SP than NKA. Whether passive immunization with alpha-SP Ab prevented bronchospastic responses to SP and NKA (i.v.), in vivo, was determined in groups of anesthetized guinea-pigs by recording pulmonary flow resistance (RL) and dynamic pulmonary elastance (EL). Injection of alpha-SP Ab (i.v., 5:1 molar ratio: alpha-SP Ab:SP total dose) did not alter baseline values of RL and EL, but markedly inhibited increases in RL and EL induced by SP and NKA (i.v.) without affecting responses to methacholine (i.v.). A control, "irrelevant" rat IgG-type antibody at a similar concentration had no effect on responses to SP or NKA. These findings indicate that passive immunization with a monoclonal alpha-SP Ab can prevent the bronchospastic effects of exogenous SP and NKA in guinea-pigs.

Topics: Amino Acid Sequence; Anesthesia; Animals; Antibodies, Monoclonal; Antibody Specificity; Bronchial Spasm; Drug Interactions; Enzyme-Linked Immunosorbent Assay; Female; Guinea Pigs; Immunization, Passive; Methacholine Chloride; Mice; Molecular Sequence Data; Neurokinin A; Rats; Substance P

1. The aim of this study was to characterize the tachykinin NK2 receptor subtype mediating the spasmogenic response in the human isolated bronchus. The motor response to neurokinin A (NKA) and the selective NK2 agonist [beta Ala8]NKA(4-10), as well as the antagonistic effects of cyclic (L659,877) and linear (MEN 10376) peptide NK2 antagonists were assessed in the presence or absence of amastatin (an inhibitor of aminopeptidases A and M). 2. NKA was more potent than [beta Ala8]NKA(4-10) in eliciting bronchoconstriction (pD2 being 7,43 and 6,87 respectively). In the presence of amastatin (1 microM), the estimated affinity of [beta Ala8]NKA(4-10), but not that of NKA, was significantly increased to yield a pD2 of 7,44. 3. L659,877 and MEN 10376 inhibited [beta Ala8]NKA(4-10)-induced contraction with similar affinities; pA2 values were 5.7 +/- 0.22 and 6.3 +/- 0.32, respectively. Amastatin (1 microM) increased the potency of MEN 10376 to 7.28 +/- 0.46, whereas that of L659,877 was unaffected. 4. In the presence of amastatin the pseudopeptide MDL 28,564 behaved as a partial agonist. 5. We conclude that the NK2 receptor subtype present in the human bronchus has properties similar to those described for the circular muscle of the human colon and thus may be classified as a 'NK2A' subtype. We show that the apparent potency of peptides, bearing N-terminal acidic residues, is influenced by an amastatin-sensitive peptidase, possibly aminopeptidase A.

Topics: Amino Acid Sequence; Anti-Bacterial Agents; Bronchi; Bronchial Spasm; Female; Humans; In Vitro Techniques; Male; Molecular Sequence Data; Neurokinin A; Peptide Fragments; Peptides; Peptides, Cyclic; Receptors, Neurokinin-2; Tachykinins

The present study characterized neurokinin receptor-mediated bronchoconstrictor responses in anesthetized guinea pigs. Thus, we have compared the actions of the selective neurokinin 1 (NK1) (CP-99,994) and neurokinin 2 (NK2) (SR-48,968) receptor antagonists against dose-response curves (DRC) induced by intravenously administered substance P (SP), neurokinin A (NKA), neurokinin B (NKB), beta Ala8-NKA (4-10),Sar9-Met(O2)11SP, and single dose (intravenous) challenge with resiniferatoxin (RTX), a capsaicin-like sensory neurotoxin, leukotriene D4 (LTD4) and antigen. The rank order of potency of the neurokinins for inducing bronchoconstriction was beta Ala8-NKA(4-10) > NKA > Sar9-Met(O2)11Sp > SP >> NKB. The DRC to the selective NK1 agonist Sar9-Met(O2)11SP was shifted to the right 10-fold by the selective NK1 antagonist, CP-99,994 (1 mg/kg, intravenously), but was not shifted by SR-48,968 (3 mg/kg, intravenously). The DRC to the selective NK2 agonist beta-Ala8-NKA(4-10) was shifted to the right 82-fold by the NK2 antagonist, SR-48,968 (1 mg/kg), but was not shifted by CP-99,994 (3 mg/kg, intravenously). SR-48,968 (1 mg/kg) also blocked NKA (3-fold shift) but did not block SP. CP-99,994 failed to produce a significant rightward shift of the DRC to either SP or NKA. However, the combination of 1 mg/kg CP-99,994 and 1 mg/kg SR-48,968 produced significant shifts of the DRCs to SP (> 5-fold) and NKA (> 300-fold). Hypotension induced by NKA and SP was also blocked by this combination.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Benzamides; Bronchial Spasm; Bronchoconstriction; Diterpenes; Dose-Response Relationship, Drug; Drug Interactions; Guinea Pigs; Male; Neurokinin A; Peptide Fragments; Piperidines; Receptors, Neurokinin-1; Receptors, Neurokinin-2; Substance P; Tachykinins

This study has examined the abilities of (+/-)-CP96345 and (+/-)-SR48968, nonpeptide antagonists selective for the tachykinin NK1 and NK2 receptors, respectively, to block bronchoconstriction caused by intravenous administration of direct-acting receptor agonists and the indirect-acting mimetics capsaicin, serotonin and 2-methyl-serotonin in the anesthetized guinea pig. The NK1 antagonist (+/-)-CP96345 was found to cause, at a maximally tolerated dose of 9 mumol/kg, an approximate 10-fold rightward shift of the dose-response curves for selective NK1 agonists substance P (SP), [Sar9,Met(O2)11]SP and Ac-[Arg6,Sar9,Met(O2)11]SP6-11 without altering responses to selective NK2 agonists neurokinin A (NKA), [Nle10]NKA4-10 or [beta-Ala8]NKA4-10. The NK2 antagonist (+/-)-SR48968 caused dose-dependent rightward shifts of the dose-response curves for the NK2 but not the NK1 agonists. Results using combinations of the receptor antagonists indicate that the NK2 agonists could cause bronchoconstriction by acting on the NK1 receptors at large doses relative to those used without antagonists. Of the agonists used here, [beta-Ala8]NKA4-10 appeared to be the most selective for the NK2 receptors. When used alone, only (+/-)-SR48968 was found to block bronchoconstriction caused by capsaicin, serotonin (after blockade of 5-HT2 receptors by LY53857) and 2-methyl-serotonin. When (+/-)-CP96345 was also given, larger additional blockade was seen with capsaicin than with serotonin or 2-methyl-serotonin as mimetic substance. Atropine caused small and variable degrees of blockade of serotonin and 2-methyl-serotonin but not of capsaicin after combinations of the two antagonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Amino Acid Sequence; Anesthesia; Animals; Benzamides; Biphenyl Compounds; Bronchial Spasm; Bronchoconstriction; Capsaicin; Guinea Pigs; Hypnotics and Sedatives; Injections, Intravenous; Male; Molecular Sequence Data; Neurokinin A; Piperidines; Receptors, Tachykinin; Serotonin

Bronchospasm induced by i.v. injection of equieffective doses of acetylcholine, capsaicin or selective tachykinin receptor agonists ([Sar9]SP sulfone or [beta-Ala8]neurokinin A (NKA-4-10)) (for NK1 and NK2 receptors, respectively) was studied in anaesthetized guinea-pigs. The NK1 and NK2 receptor antagonists, (+/-)-CP96,345 (3 mumol/kg i.v.) and MEN 10,376 (3 mumol/kg i.v.), selectively abolished the bronchoconstriction induced by the respective agonist, showing that both NK1 and NK2 receptors mediate bronchoconstriction in guinea-pig airways and that they are activated independently. Capsaicin-induced bronchospasm was inhibited by atropine (1.5 mumol/kg i.v.) and MEN 10,376 (3 mumol/kg i.v.), but unaffected by (+/-)-CP96,345 (3 mumol/kg i.v.). Hexamethonium (79 mumol/kg i.v.), propranolol (17 mumol/kg i.v.) and physostigmine (0.9 mumol/kg i.v.) enhanced the airway constriction induced by acetylcholine, capsaicin, [Sar9]SP sulfone or [beta-Ala8]NKA-(4-10) while guanethidine (67 mumol/kg s.c. for two days) increased only bronchoconstriction induced by capsaicin or the selective NK2 receptor agonist. In hexamethonium-treated animals, MEN 10,376 still abolished the increase in insufflation pressure induced by [beta-Ala8]NKA-(4-10) and reduced the increase elicited by capsaicin. In summary, in anaesthetized guinea pig i.v. capsaicin-induced bronchospasm through activation of postjunctional NK2 (but not NK1) receptors along with activation of cholinergic pathways. This motor response is moderated by the simultaneous stimulation of a sympathetic bronchodilating mechanism(s), possibly through activation of NK2 receptors localized in sympathetic ganglia.

Topics: Anesthesia; Animals; Atropine; Biphenyl Compounds; Bronchial Spasm; Capsaicin; Guinea Pigs; Hexamethonium; Hexamethonium Compounds; Male; Neurokinin A; Peptide Fragments; Receptors, Neurotransmitter; Receptors, Tachykinin; Tachykinins

1. The effect of systemic administration of ruthenium red on bronchospasm induced by acetylcholine, capsaicin or selective tachykinin receptor agonists ([Sar9]SP sulfone or [beta Ala8]-neurokinin A (NKA)-(4-10) for NK-1 and NK-2 receptors, respectively) was studied in anaesthetized guinea-pigs. 2. The bronchospasm induced by capsaicin was reduced by ruthenium red, which did not affect the response induced by acetylcholine. Atropine, which totally blocked the response to acetylcholine, also partially blocked the bronchospasm induced by capsaicin. 3. The inhibitory action of atropine and ruthenium red on the bronchospasm produced by capsaicin was additive, independently from the order of administration of the two antagonists. 4. Ruthenium red induced an increase in [Sar9]SP sulfone-bronchospasm and a marked enhancement of the bronchomotor response to [beta Ala8]NKA-(4-10). This latter was antagonized by the prior administration of the selective NK-2 receptor antagonist MEN 10,376. 5. Pretreatment with guanethidine or propranolol increased the airway constriction induced by [beta Ala8]NKA-(4-10). Furthermore, pretreatment with guanethidine prevented the enhancement induced by ruthenium red, showing that activation of NK-2 receptors influences the sympathetic bronchodilator drive to the airways. 6. It is concluded that ruthenium red antagonizes selectively the in vivo excitatory effect of capsaicin in guinea-pig airways. Furthermore, the additivity of the blocking action of ruthenium red and atropine indicates that two distinct mechanisms take place in bronchospastic response to i.v. capsaicin in this species.

Topics: Anesthesia; Animals; Bronchial Spasm; Bronchoconstriction; Capsaicin; Guanethidine; Guinea Pigs; Male; Neurokinin A; Peptide Fragments; Propranolol; Receptors, Neurotransmitter; Receptors, Tachykinin; Ruthenium Red

The ability of substance P, neurokinin A and its C-terminal fragment, neurokinin A-(4-10), to elicit NK-1 (salivation) and NK-2 (bronchospasm) receptor-mediated responses was investigated in anaesthetized guinea-pigs. Neurokinin A-(4-10) produced a dose-related increase in tracheal insufflation pressure and its maximal effect was similar to that elicited by neurokinin A and significantly greater than that of substance P. On the other hand substance P induced a potent dose-dependent increase of salivation while neurokinin A was significantly less potent. Neurokinin A-(4-10) did not exert any sialologic effect even at the dose of 100 nM/kg. These findings indicate that neurokinin A-(4-10) might be a valuable pharmacological tool for characterizing the involvement of NK-1 and NK-2 receptors in physiological responses in vivo.

Topics: Anesthesia; Animals; Bronchial Spasm; Guinea Pigs; Male; Neurokinin A; Neuropeptides; Peptide Fragments; Receptors, Neurokinin-2; Receptors, Neurotransmitter; Salivation; Substance P; Trachea