Relationship between sensitivity and density of muscarinic receptors in single smooth muscle cells of guinea pig taenia caecum prepared under three conditions.
The relationship between the sensitivity (the pD2 value) of carbachol and the density (the total concentration of receptors) of muscarinic receptors using single cells from the guinea pig taenia caecum prepared with a mixture of crude collagenase and trypsin inhibitor, purified collagenase alone, and a mixture of purified collagenase and papain was examined. The sensitivity of the single cells prepared with a mixture of purified collagenase and papain was about 10 times more effective than that of the single cells prepared under other conditions. The dissociation constant of [3H]quinuclidinyl benzilate (QNB) and Hill's coefficient did not change in the single cells prepared under the three conditions, though the maximum binding sites were significantly greater in the cells prepared with the mixture of purified collagenase and papain than in those prepared by other means. These results suggest that the increase in the sensitivity of carbachol obtained in the single cells prepared with this mixture is due to the increase in the density of muscarinic receptors and also suggest that the effects of this enzyme mixture may be due to an increase in the incorporation of newly synthesized receptors and (or) changes in receptor turnover.
Koike
K
K
Department of Chemical Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan.
Ohtsuki
H
H
Takayanagi
I
I
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002432:Cecum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007700:Kinetics; D003012:Microbial Collagenase / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D010206:Papain / Q000494:pharmacology; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000187:drug effects*; D014361:Trypsin Inhibitors / Q000494:pharmacology
D011976:Receptors, Muscarinic; D014361:Trypsin Inhibitors; D011813:Quinuclidinyl Benzilate; D002217:Carbachol; D010206:Papain; D003012:Microbial Collagenase