Effect of pilocarpine on propranolol-induced bronchoconstriction in asthma.
To investigate whether increased release of acetylcholine may be involved in propranolol-induced bronchoconstriction (PIB), the inhibitory effect of pilocarpine (Pilo), an agonist of M2-muscarinic receptors that in 11 stable asthmatic subjects. The bronchial responsiveness to Pilo was also measured in terms of Dmin, defined as the cumulative dose at the point where respiratory resistance (Rrs) began to increase. In PIB, the maximum increase in Rrs (Rrs max) after stopping inhalation for 1 min was measured. Atropine reversed PIB. After pilocarpine pretreatment at a dose equal to Dmin, Rrs max divided by baseline Rrs decreased significantly from 206.6 +/- 61.1 to 163.0 +/- 42.6% (mean +/- SD) (p = 0.001). The ratio of PIB (Rrs max/baseline Rrs) with Pilo to PIB without Pilo correlated inversely according to the pretreatment dose (Dmin) of Pilo (p < 0.05). These results suggest increased release of acetylcholine in PIB and that M2-muscarinic receptors are at least in part functioning in stable asthmatic airways.
Okayama
M
M
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Shen
T
T
Midorikawa
J
J
Lin
J T
JT
Inoue
H
H
Takishima
T
T
Shirato
K
K
D000109:Acetylcholine / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000403:Airway Resistance / Q000187:drug effects; D001249:Asthma / Q000175:diagnosis / Q000503:physiopathology*; D001285:Atropine / Q000494:pharmacology; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction / Q000187:drug effects* / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010862:Pilocarpine / Q000494:pharmacology*; D011292:Premedication; D011433:Propranolol / Q000494:pharmacology*; D011976:Receptors, Muscarinic / Q000187:drug effects*; D014797:Vital Capacity / Q000187:drug effects
D011976:Receptors, Muscarinic; D010862:Pilocarpine; D001285:Atropine; D011433:Propranolol; D000109:Acetylcholine