[Study on the muscarinic receptor and its subtypes in patients with chronic obstructive pulmonary disease].
OBJECTIVE
To investigate the M receptor and its subtypes in the lung tissue of patients with chronic obstructive pulmonary disease (COPD).


METHODS
Muscarinic cholinergic receptors have been identified and characterized by radioligand binding assay in the lung tissue specimens of patients with COPD. Competitive binding experiments with pirenzepine and methoctramine were used to characterize muscarinic subtypes.


RESULTS
The contents of M-receptor were (64 +/- 10), (42 +/- 18) fmol/mg. protein in normal group and COPD patients respectively. No significant difference was observed in antagonist affinity (K(D)) among normal group and COPD patients. The ratio of subtype M(1) was higher in COPD patients (67.2 +/- 2.7)% than in normal group (74.2 +/- 4.8)%, M(2) was lower [(29.3 +/- 1.7)% vs (16.8 +/- 4.4)%] and M(3) was higher [(3.6 +/- 2.9) % vs (9.3 +/- 4.1)%] respectively.


CONCLUSIONS
The number of muscarinic cholinergic receptors is decreased in COPD patients, but the ratios of subtype M(1) and M(3) are increased and the subtype M(2) is decreased. The changes of the distribution of the subtypes of M-receptors is an important pathophysiologic change of COPD.
Shen
N
N
Department of Respiratory Medicine, The Third Hospital, Beijing University, Beijing 100083, China.
Yao
W
W
Zhu
H
H
D005260:Female; D006801:Humans; D008168:Lung / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism*; D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D011976:Receptors, Muscarinic / Q000378:metabolism*
D043643:Receptor, Muscarinic M1; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D011976:Receptors, Muscarinic