Nonadrenergic inhibitory nerves attenuate neurally mediated contraction in cat bronchi

1990 ◽  
Vol 69 (5) ◽  
pp. 1594-1598 ◽  
Author(s):  
T. Aikawa ◽  
K. Sekizawa ◽  
S. Itabashi ◽  
H. Sasaki ◽  
T. Takishima
Keyword(s):  
Contractile Response ◽  
Stimulus Frequency ◽  
Electrical Field Stimulation ◽  
Inhibitory Effect ◽  
Field Stimulation ◽  
Inhibitory Effects ◽  
Electrical Field ◽  
Calcitonin Gene ◽  
Contraction And Relaxation ◽  
Biphasic Responses

Effects of nonadrenergic and noncholinergic (NANC) inhibitory nerves on cholinergic neurotransmission were examined in isolated bronchial segments from cats in the presence of propranolol (10(-6) M) and indomethacin (10(-6) M) by use of electrical field stimulation (EFS) techniques. EFS caused contraction alone in tissues at the baseline tension and biphasic responses (contraction and relaxation) in tissues precontracted with 5-hydroxytryptamine. Contraction was abolished by atropine (10(-6) M), and relaxation was abolished by tetrodotoxin (10(-6) M). At the baseline tension, EFS at frequencies greater than 10 Hz inhibited the subsequent (4 min later) contraction induced by EFS at 1-5 Hz. EFS-induced inhibition was stimulus frequency dependent and reached maximum at 20 Hz. However, EFS at 20 Hz did not inhibit the subsequent contractile response to acetylcholine (10(-7) to 10(-3) M). Exogenously applied vasoactive intestinal peptide mimicked EFS-induced inhibitory effects, but substance P and calcitonin gene-related peptide did not. The inhibitory effect of EFS at 20 Hz was not altered by pyrilamine, cimetidine, naloxone, methysergide, phentolamine, BW755C, AF-DX 116, or removal of epithelium. These results imply that the NANC transmitter acts via presynaptic cholinergic receptors.

Pharmacologic responses of the mouse urinary bladder

Open Medicine ◽  
2009 ◽  
Vol 4 (2) ◽  
pp. 192-197 ◽  
Author(s):  
A. Canda ◽  
Christopher Chapple ◽  
Russ Chess-Williams
Keyword(s):  
Nitric Oxide ◽  
Urinary Bladder ◽  
Electrical Field Stimulation ◽  
Inhibitory Effect ◽  
Minor Role ◽  
Detrusor Muscle ◽  
Field Stimulation ◽  
Muscarinic Agonists ◽  
Electrical Field ◽  
M3 Receptor

AbstractThe aim of the study was to determine pathways involved in contraction and relaxation of the mouse urinary bladder. Mouse bladder strips were set up in gassed Krebs-bicarbonate solution and responses to various drugs and electrical field stimulation were obtained. Isoprenaline (b-receptor agonist) caused a 63% inhibition of carbachol precontracted detrusor (EC50=2nM). Carbachol caused contraction (EC50=0.3µM), responses were antagonised more potently by 4-DAMP (M3-antagonist) than methoctramine (M2-antagonist). Electrical field stimulation caused contraction, which was inhibited by atropine (60%) and less by guanethidine and α,β-methylene-ATP. The neurogenic responses were not potentiated by inhibition of nitric oxide synthase. Presence of an intact urothelium significantly depressed responses to carbachol (p=0.02) and addition of indomethacin and L-NNA to remove prostaglandin and nitric oxide production respectively did not prevent the inhibitory effect of the urothelium. In conclusion, b-receptor agonists cause relaxation and muscarinic agonists cause contraction via the M3-receptor. Acetylcholine is the main neurotransmitter causing contraction while nitric oxide has a minor role. The mouse and human urothelium are similar in releasing a factor that inhibits contraction of the detrusor muscle which is unidentified but is not nitric oxide or a prostaglandin. Therefore, the mouse may be used as a model to study the lower urinary tract.

Effects of mucosal removal on guinea-pig airway smooth muscle responsiveness

1986 ◽  
Vol 70 (6) ◽  
pp. 571-575 ◽  
Author(s):  
Christopher Murlas
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Airway Smooth Muscle ◽  
Contractile Response ◽  
Electrical Field Stimulation ◽  
Physiological Salt Solution ◽  
Induced Responses ◽  
Field Stimulation ◽  
Electrical Field ◽  
Airway Mucosa

1. The contractile response to histamine, acetylcholine (ACh), KCl or electrical field stimulation (EFS) was examined in paired tracheal rings (one of each being denuded by mucosal rubbing), which were mounted in muscle chambers filled with a continuously aerated physiological salt solution at 37°C. 2. Removal of the respiratory mucosa increased the sensitivity of airway muscle to ACh, histamine and EFS, but not to KCl. The hypersensitivity of denuded rings to histamine and EFS was greater than to ACh. Atropine reduced the histamine hypersensitivity observed. 3. Pretreating intact preparations with indomethacin augmented their responsiveness to EFS, histamine and ACh. 4. Indomethacin augmentation of histamine- and EFS-induced responses was greater in preparations without epithelium. 5. We conclude that the airway mucosa may be associated with a factor that reduces airway smooth muscle responsiveness to stimulation.

Cholinergic and nonadrenergic mechanisms in human and guinea pig airways

1984 ◽  
Vol 56 (4) ◽  
pp. 958-965 ◽  
Author(s):  
S. M. Taylor ◽  
P. D. Pare ◽  
R. R. Schellenberg
Keyword(s):  
Guinea Pig ◽  
Contractile Response ◽  
Electrical Field Stimulation ◽  
Field Stimulation ◽  
Inhibitory Pathway ◽  
Electrical Field ◽  
Methods Of Analysis ◽  
Human Airways ◽  
Human Bronchi

Electrical field stimulation (70 V, 1 ms, 0.2–500 Hz) of human bronchial strips and guinea pig tracheal chains produced contractile and relaxant responses. Contractions were blocked by atropine, 10(-6) M, and tetrodotoxin (TTX), 0.1–1.0 micrograms/ml, demonstrating a cholinergic excitatory neural component. Frequencies causing half-maximal contractile response to field stimulation (EFc 50) were 10 +/- 2 Hz for guinea pig and 13 +/- 1 Hz for human airways. Relaxations were unmasked by atropine 10(-6) M and slightly diminished by propranolol in guinea pig but not human airways, demonstrating a predominantly nonadrenergic inhibitory pathway in both species. Relaxation of intrinsic tone occurred at stimulation frequencies of 1 Hz or more. Frequencies causing half-maximal relaxation (EFi 50) were 3.5 +/- 0.3 Hz for guinea pig trachealis and 38 +/- 6 Hz for human bronchi. Following 1 microgram/ml TTX, EFi 50 values increased to 104 +/- 12 and 70 +/- 14 Hz, respectively. Frequencies of field stimulation that were inhibitable by TTX (less than or equal to 20 Hz) induced greater relaxation in guinea pig than human airways (70 vs. 10% of the maximal relaxation to 10(-2) M theophylline, respectively). The methods of analysis outlined in this study can be used to compare relative degrees of functional innervation between tissues from the same or different species.

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