As. Braverman et Mr. Ruggieri, Selective alkylation of rat urinary bladder muscarinic receptors with 4-DAMP mustard reveals a contractile function for the M-2 muscarinic receptor, J RECEPT SI, 19(5), 1999, pp. 819-833
Citations number
17
Categorie Soggetti
Cell & Developmental Biology
Journal title
JOURNAL OF RECEPTOR AND SIGNAL TRANSDUCTION RESEARCH
Our previous data indicate that M-3 muscarinic receptors mediate carbachol
induced bladder contractions. The data presented here were obtained by sele
ctive alkylation of M-3 receptors with 4-DAMP mustard and suggest that the
M-2 receptor subtype may be involved in inhibition of beta-adrenergic recep
tor induced relaxation, therefore, allowing recontraction. Alkylation resul
ted in 85% of M-3 receptors and 65% of M-2 receptors unable to bind radioli
gand as demonstrated by subtype selective immunoprecipitation. Rat bladder
strips subjected to our alkylation procedure contracted submaximally, and d
irect carbachol contractions were inhibited by antagonists with affinities
consistent with M-3 receptor mediated contraction. In contrast, the affinit
ies of antagonists for inhibition of carbachol induced recontractions follo
wing isoproterenol stimulated relaxation in the presence of 90 mM KCl, indi
cated a contractile function for the M-2 receptor that was not observed in
control strips. In conclusion, these studies demonstrate a possible role fo
r the M-2 subtype in bladder smooth muscle contraction.