Identification of muscarinic receptor subtypes of cultured smooth muscle cells and tissue of human bladder body.
BACKGROUND
Muscarinic receptor subtypes of cultured smooth muscle cells from the human bladder body were investigated by the receptor binding assay method. The result was compared with that obtained from the human bladder body tissue to confirm whether the receptor subtypes of the cells are not changed after several passages of cell culture.


METHODS
Inhibitory effects of various muscarinic antagonists on the binding of [3H]-N-methylscopolamine ([3H]-NMS) to membrane preparations obtained from cultured smooth muscle cells from the fourth subculture of the human bladder body were compared with those prepared from the human bladder body tissue and cells expressing human muscarinic receptor subtypes.


RESULTS
Binding-inhibition constants (pKi) for atropine, pirenzepine, methoctramine, 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP), oxybutynin and propiverine obtained from membrane preparations of cultured smooth muscle cells were 8.91, 6.35, 8.24, 8.53, 7.29 and 5.61, respectively. pKi values of these muscarinic receptor antagonists against the membrane preparation of human bladder body tissue were 9.08, 6.66, 8.05, 8.79, 7.53 and 6.04, respectively. pKi values of cultured smooth muscle cells and tissue from human bladder body were correlated closely with those of insect cells expressing the cloned human M2 receptor subtype.


CONCLUSIONS
The binding affinities for various muscarinic receptor antagonists of cultured human smooth muscle cells were maintained through the fourth subculture and it was suggested that the M2 receptor subtype is predominantly expressed in cultured smooth muscle cells of human bladder body as well as in tissue of the human bladder body.
Kiwamoto
H
H
Department of Urology, Kinki University School of Medicine, Osaka, Japan. urology@med.kindai.ac.jp
Ma
F H
FH
Higashira
H
H
Park
Y C
YC
Kurita
T
T
D002478:Cells, Cultured; D006801:Humans; D018727:Muscarinic Antagonists / Q000378:metabolism / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000737:chemistry / Q000378:metabolism*; D019832:N-Methylscopolamine / Q000378:metabolism*; D010276:Parasympatholytics / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000145:classification / Q000187:drug effects / Q000378:metabolism*; D001743:Urinary Bladder / Q000737:chemistry / Q000378:metabolism*
D018727:Muscarinic Antagonists; D010276:Parasympatholytics; D011976:Receptors, Muscarinic; D019832:N-Methylscopolamine