Jpn. J. Pharmacol. 73 (1), 1-22 (1997)
Drug Receptor Mechanisms in Smooth Muscle: beta-Chloroethylamine-Sensitive
and -Resistant Receptor Mechanisms
Issei Takayanagi, Katsuo Koike, Mitsutoshi Satoh and Ayako Okayasu
Department of Chemical Pharmacology, Toho University School of Pharmaceutical
Sciences, Chiba 274, Japan
Abstract: Both alpha1-adrenoceptors and M3-cholinoceptors can
be divided into two subtypes discriminated by the beta-chloroethylamines,
chloroethylclonidine and propylbenzilylcholine mustard (PrBCM), only in
the presence of GTP. The full agonists interact with both subtypes to induce
responses. The partial agonists activate one of them to induce responses
but behave as competitive antagonists when they interact with the other.
The responses mediated through the receptors that are activated by the partial
agonists are resistant to myosin light chain kinase inhibitors, while the
response through the activation of the other receptors are suppressed by
the inhibitors. The receptor stimulations through alpha1A-adrenoceptor and
PrBCM-sensitive M3-cholinoceptor subtypes mainly activate the myosin light
chain-phosphorylation-independent pathway mediated through protein kinase
C and low molecular weight GTP-binding protein, whereas the stimulations
through alpha1B-adrenoceptors and the PrBCM-phosphorylation-dependent pathway
are directly related to Ca2+/calmodulin.
Keywords: Drug receptor mechanism, beta-Chloroethylamine, M3-Cholinoceptor,
alpha1-Adrenoceptor, Signal transduction
Copyright© The Japanese Pharmacological Society 1997
[Back to TOC]