Effect of steroid hormones on muscarinic receptors of bronchial smooth muscle.
1. Glucocorticosteroid may relieve bronchospasm by mediating changes in the muscarinic receptor concentration and/or its affinity. 2. Cholinergic muscarinic receptors were determined by using Scatchard's plots from radioligand binding assays of 0.13-3.2 nM [3H]quinuclidinyl benzylate binding to the membrane fraction of bronchial smooth muscle (BSM). 3. The concentration of muscarinic receptor in BSM of normal rat was 57 +/- 3 fmol mg protein and the dissociation constant was 0.07 +/- 0.02 nM. Dexamethasone and corticosterone reduced muscarinic receptor concentration to 50-60% of basal with no changes in receptor affinity. No changes were found in rat treated with deoxycorticosterone. 4. These findings suggest that glucocorticoids but not mineralocorticoid relieve bronchospasm at least partly by reducing the cholinergic hypersensitivity.
Nabishah
B M
BM
Departments of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia.
Morat
P B
PB
Kadir
B A
BA
Khalid
B A
BA
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D001980:Bronchi / Q000187:drug effects; D003345:Corticosterone / Q000494:pharmacology; D003900:Desoxycorticosterone / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D005938:Glucocorticoids / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008901:Mineralocorticoids / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects*; D013256:Steroids / Q000494:pharmacology*; D013950:Thymus Gland / Q000187:drug effects
D005938:Glucocorticoids; D008901:Mineralocorticoids; D011976:Receptors, Muscarinic; D013256:Steroids; D003900:Desoxycorticosterone; D011813:Quinuclidinyl Benzilate; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone