Muscarinic receptor subtypes in feline tracheal submucosal gland secretion.
To determine what muscarinic receptor subtype regulates [Ca2+]i mediating airway submucosal gland secretion, we examined the effects of atropine (Atr), pirenzepine (PZ), 11([2-(diethylamino)methyl-1-piperidinyl] acetyl)-5,11-dihydro-6H-pyrido (2,3-b)(1,4)-benzo-diazepin-6-one (AF-DX116) and 4-diphenylacetoxy-N-methyl-piperidine methiodide (4-DAMP) on methacholine (MCh)-evoked [Ca2+]i rise in acinar cells, and compared this with mucus glycoprotein (MGP) and electrolyte secretion evoked by MCh from submucosal glands isolated from feline trachea. [Ca2+]i was measured with the Ca(2+)-sensitive fluorescent dye, fura 2. We determined MGP secretion by measuring TCA-precipitable 3H-labeled glycoconjugates and electrolyte secretion by the change in the rate constant of 22Na-efflux from isolated glands. Half-maximal inhibitory concentrations (IC50) of PZ, AF-DX116, 4-DAMP, and Atr against MCh-evoked [Ca2+]i rise were 10(-7) M, 6 x 10(-6) M, 8 x 10(-9) M, and 6 x 10(-9) M, respectively. IC50 of PZ, AF-DX116, 4-DAMP, and Atr against MCh-evoked MGP secretion were 10(-6) M, 2 x 10(-5) M, 8 x 10(-9) M, and 6 x 10(-9) M, respectively. MCh (10(-5) M)-evoked 22Na efflux was significantly inhibited by 10(-7) M 4-DAMP and 10(-7) M Atr (P less than 0.01, each) but not by 10(-7) M PZ. Receptor binding assays with [3H]quinuclidinyl benzilate showed that the Ki values for PZ, AF-D x 116, 4-DAMP and Atr were 2.2 x 10(-8) M, 6.6 x 10(-7) M, 6.2 x 10(-10) M, and 2.9 x 10(-10) M, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Ishihara
H
H
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Shimura
S
S
Satoh
M
M
Masuda
T
T
Nonaka
H
H
Kase
H
H
Sasaki
T
T
Sasaki
H
H
Takishima
T
T
Tamura
K
K
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002415:Cats; D005088:Exocrine Glands / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism; D009092:Mucous Membrane / Q000378:metabolism; D009994:Osmolar Concentration; D010277:Parasympathomimetics / Q000494:pharmacology; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000145:classification / Q000378:metabolism / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D014132:Trachea / Q000378:metabolism*
D006023:Glycoproteins; D010277:Parasympathomimetics; D011976:Receptors, Muscarinic; C047874:gastric mucus glycoproteins; D011813:Quinuclidinyl Benzilate; D012964:Sodium; D002118:Calcium