Muscarinic receptor subtypes in the rat prostate gland.
Muscarinic receptor subtypes mediating carbachol-induced contractions of the rat prostatic smooth muscle were determined. The rank order of potency of muscarinic receptor antagonists in blocking the effects of carbachol was (mean pKB estimates in parentheses): atropine (8.90) >> para-fluorohexahydrosiladifenidol (7.75) > or = hexahydrosiladifenidol (7.62) > methoctramine (6.89) > or = pirenzepine (6.68) > or = himbacine (6.67). The specific binding of [3H]quinuclidinyl benzilate to the rat prostatic homogenates was competitively inhibited by (mean pKi values in parentheses): atropine (8.89) >> hexahydrosiladifenidol (7.86) > para-fluorohexahydrosiladifenidol (7.28) > or = himbacine (7.22) > pirenzepine (6.63) > or = methoctramine (6.38). These profiles, whilst different, indicate the probable involvement of muscarinic M3 receptors in the carbachol-induced contraction.
Lau
W A
WA
Department of Pharmacology, Monash University, Clayton, Vic., Australia.
Pennefather
J N
JN
D000818:Animals; D001667:Binding, Competitive; D018678:Cholinergic Agents / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D011467:Prostate / Q000378:metabolism*; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D017207:Rats, Sprague-Dawley; D011976:Receptors, Muscarinic / Q000145:classification* / Q000378:metabolism
D018678:Cholinergic Agents; D011976:Receptors, Muscarinic; D011813:Quinuclidinyl Benzilate