Nonadrenergic inhibitory innervation to the airways of the newborn cat

Waldron, M. A.; Connelly, B. J.; Fisher, JohnH

doi:10.1152/jappl.1989.66.4.1995

Cited by 16 publications

(2 citation statements)

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“…Propranolol has no effect on the inhibitory neural responses to the tracheobronchial tree of the foetal pig and only a partial antagonistic effect on central bronchi in the adult (Mitchell et al , 1990). As some neural and motor responses of the lung show maturation around birth or during the neonatal period (Waldron et al , 1989; Sparrow & Mitchell, 1990; Haxhiu‐Proskurica et al , 1992; 1993), it is possible that the nerves conferring the strong inhibitory control over the tracheobronchial tree also differ with development.…”

Section: Introductionmentioning

confidence: 99%

Transition of functional innervation in the developing porcine airway from nitrergic to catecholaminergic

Connellan

Mitchell

1998

British J Pharmacology

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1 We determined the distribution and chemical nature of the inhibitory neurotransmitter(s) to the airway smooth muscle (ASM) before and after birth. 2 Relaxation responses to electrical ®eld stimulation (EFS) were studied in isovolumic bronchial segments from foetal (approximately 100/115 days gestation) and adult (25 kg) pigs, and in isovolumic tracheal segments from the foetus, and tracheal smooth muscle strips from the adult pig. Preparations were conditioned in low doses of atropine (10 77 M) to reduce the eects of excitatory neurotransmission and then exposed to carbachol to produce submaximal muscle tone. Some studies were also carried out on bronchial segments from 4 week old pigs. 3 EFS (65 V, 2 ms, 5 ± 20 Hz for 5 s) produced a TTX-sensitive relaxation in epithelium-intact and epithelium-denuded preparations. In foetal bronchial and tracheal preparations, EFS-induced relaxation was strongly inhibited by N G -nitro-L-arginine (L-NOARG, 10 76 to 10 74 M; P50.01 ± 0.001). However, in the adult, only relaxations of the trachea were inhibited by L-NOARG; bronchi were resistant to L-NOARG and also to N-nitro-L-arginine methyl ester (L-NAME, 5 The onset of relaxation to EFS was more prompt and the rate of relaxation more rapid in foetal bronchi than in adult bronchi (P50.0005). Maximum relaxation and recovery times were the same. 6 Foetal and adult bronchi were relaxed by sodium nitroprusside (SNP) with similar sensitivity and maximum eect. The rate of relaxation to SNP was not dierent in the two ages. 7 In the absence of atropine and carbachol, excitatory cholinergic responses to EFS (65 V, 2 ms, 5 Hz for 20 s) were not altered by L-NOARG (10 74 M) or L-NAME (10 74 M) in the adult bronchus but were modestly increased by L-NOARG in the foetal bronchus (P50.01). 8 The tracheobronchial tree appears functionally innervated by nitrergic input to the smooth muscle before birth. However, at or after 4 weeks of age the inhibitory neural input to the bronchi is catecholaminergic, but it remains nitrergic in the trachea. There is also a weak nitrergic pre-or postsynaptic inhibition of the eects of cholinergic neurotransmission in the foetal bronchus but not in the adult.

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Section: Introductionmentioning

confidence: 99%

Transition of functional innervation in the developing porcine airway from nitrergic to catecholaminergic

Connellan

Mitchell

1998

British J Pharmacology

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“…In terms of neurally mediated airway function in mammalian models, age-related changes in the NANCi component of neural control were documented in some normal species, 4-6 but possibly not in others. 22 The current study expands on these observations, focusing on the cholinergic component of neural control of airways early in life. Rabbits were used for the study for several reasons.…”

Section: Discussionmentioning

confidence: 91%

Mechanisms determining cholinergic neural responses in airways of young and mature rabbits

Larsen

Loader

Nguyen

et al. 2004

Pediatric Pulmonology

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Neural pathways help control airway caliber and responsiveness. Yet little is known of how neural control changes as a function of development. In rabbits, we found electrical field stimulation (EFS) of airway nerves led to more marked contractile responses in 2- vs. 13-week-old animals. This enhanced response to EFS may be due to prejunctional, junctional, and/or postjunctional neural mechanisms. We assessed these mechanisms in airways of 2- and 13-week-old rabbits. The contractile responses to methacholine did not differ in the groups, suggesting postjunctional neural events are not primarily responsible for differing responses to EFS. To address junctional events, acetylcholinesterase (AChE) was measured (spectrophotometry). AChE was elevated in 2-week-olds. However, this should lead to less and not greater responses. Prejunctionally, EFS-induced acetylcholine (ACh) release was assessed by HPLC. Airways of 2-week-old rabbits released significantly more ACh than airways from mature rabbits. Choline acetyltransferase, a marker of cholinergic nerves, was not different between groups, suggesting that more ACh release in young rabbits was not due to increased nerve density. ACh release in the presence of polyarginine increased significantly in both groups, supporting the presence of functional muscarinic autoreceptors (M2) at both ages. Because substance P (SP) increases release of ACh, SP was measured by ELISA. This neuropeptide was significantly elevated in airways of younger rabbits. Nerve growth factor (NGF) increased SP and was also significantly increased in airways from younger rabbits. This work suggests that increases in EFS-induced responsiveness in young rabbits are likely due to prejunctional events with enhanced release of ACh. Increases in NGF and SP early in life may contribute to this increased responsiveness.

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Distribution of vasoactives intestinal peptide‐ and substance P‐containing nerves originating from neurons of airway ganglia in cat bronchi

Dey

Altemus

Michalkiewicz

1991

J of Comparative Neurology

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This study examined the possibility that vasoactive intestinal peptide (VIP)- and substance P (SP)-containing nerve fibers in bronchial smooth muscle, glands, epithelium, and blood vessels originate from neurons of airway ganglia. Explants of airway walls were maintained in culture with the expectation that nerve fibers from neurons of airway ganglia would remain viable, whereas fibers originating from neurons not present in the airway walls would degenerate. Airways were dissected and placed into culture dishes containing CMRL 1066 medium for 3, 5, and 7 days. In controls (noncultured), VIP- and SP-like immunoreactivity was observed in nerve fibers associated with bronchial smooth muscle, glands, and blood vessel walls and in nerve cell bodies of airway ganglia. Nerve fibers containing SP were also observed within the bronchial epithelium. After 3, 5, and 7 days in culture, VIP- and SP-containing fibers were identified in all of the same locations except in the airway epithelium where SP-containing fibers could not be demonstrated. VIP and SP were frequently colocalized in the same nerve fibers of bronchial smooth muscle and glands in controls and cultured airways. There were no statistically significant differences in nerve fiber density for either VIP- or SP-containing fibers in bronchial smooth muscle between controlled and cultured airways. VIP concentrations in cultured airways were significantly less than in controls. The results suggest that a large proportion of VIP- and SP-containing nerve fibers supplying bronchial smooth muscle, glands, and blood vessels in the airways originate from neurons of airway ganglia.

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Nonadrenergic inhibitory innervation to the airways of the newborn cat

Cited by 16 publications

References 0 publications

Transition of functional innervation in the developing porcine airway from nitrergic to catecholaminergic

Transition of functional innervation in the developing porcine airway from nitrergic to catecholaminergic

Mechanisms determining cholinergic neural responses in airways of young and mature rabbits

Distribution of vasoactives intestinal peptide‐ and substance P‐containing nerves originating from neurons of airway ganglia in cat bronchi

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