Cholinergic influence on the sensitivity of cough reflex in awake guinea-pigs.
1. We studied the effects of an intraperitoneal (i.p.) administration of atropine on bronchomotor tone induced by carbachol aerosols in anaesthetized and ventilated guinea-pigs and on the sensitivity of cough reflex to capsaicin aerosols in awake guinea-pigs. 2. The intraperitoneal administration of atropine (10(-8)-10(-6) M kg(-1)) reduced carbachol (8 mg ml(-1); 1 min)-induced increases in pulmonary insufflation pressure and a complete inhibition was achieved at a dose of 10(-6) M kg(-1) in anaesthetized guinea-pigs. 3. In awake guinea pigs, capsaicin aerosols (10(-5)-10(-3) M) caused dose-dependent increases in the number of coughs. Atropine (10(-7)-10(-6) M kg(-1) i.p.) shifted the dose-response curves to capsaicin to the right in a dose-dependent fashion. Carbachol aerosols, at the maximal concentration (2 mg ml(-1)) that did not cause bronchoconstriction, shifted them to the left compared with the control. 4. Atropine (10(-6) M kg(-1) i.p.) significantly increased the provocative concentration of capsaicin that caused five coughs (P < 0.01) and carbachol aerosols (2 mg ml(-1)) significantly decreased it (P < 0.01). 5. We conclude that cholinergically mediated airway tone regulates cough sensitivity in awake guinea pigs.
Jia
Y X
YX
Department of Geriatric Medicine, Tohoku University School of Medicine, Sendai, Japan.
Sekizawa
K
K
Sasaki
H
H
D000280:Administration, Inhalation; D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D016084:Bronchoconstriction / Q000187:drug effects*; D002211:Capsaicin / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology*; D018679:Cholinergic Agonists / Q000494:pharmacology*; D003371:Cough / Q000139:chemically induced / Q000209:etiology*; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D007274:Injections, Intraperitoneal; D008297:Male; D010276:Parasympatholytics / Q000494:pharmacology*; D012123:Pulmonary Ventilation
D018679:Cholinergic Agonists; D010276:Parasympatholytics; D001285:Atropine; D002217:Carbachol; D002211:Capsaicin