Selective antagonism by pirenzepine and N-methyl-scopolamine on muscarinic receptor subtypes of the rat vas deferens.
1. The effects of pirenzepine and N-methyl-scopolamine on the responses to ACh in the isolated rat vas deferens were studied. 2. Pirenzepine was inactive at the M2-ACh receptor. 3. N-methyl-scopolamine was a competitive antagonist (pA2 = 8.76) at M2-ACh receptor, alone or in the presence of pirenzepine. 4. Pirenzepine and N-methyl-scopolamine were both non-competitive antagonists at M1-ACh receptor. 5. The mixture of pirenzepine and N-methyl-scopolamine did not alter the type of antagonism demonstrated by each drug at the M1-ACh receptor.
Department of Pharmacology, School of Medicine, Central Caribbean University, Cayey, PR 00634.
H F
HF
Miranda
W I
WI
Silva
W W
WW
Wolstenholme
N
N
Cuevas
D000818:Animals; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000294:innervation; D019832:N-Methylscopolamine; D010276:Parasympatholytics / Q000494:pharmacology*; D010890:Pirenzepine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects*; D012602:Scopolamine Derivatives / Q000494:pharmacology*; D014649:Vas Deferens / Q000187:drug effects
D010276:Parasympatholytics; D011976:Receptors, Muscarinic; D012602:Scopolamine Derivatives; D010890:Pirenzepine; D019832:N-Methylscopolamine