The effects of neostigmine on the response of the rat anococcygeus muscle to field stimulation are not a consequence of cholinesterase inhibition.
Neostigmine (5 X 10(-7) to 5 X 10(-6) M) and physostigmine (10(-5) M) each augment the responses of the rat anococcygeus muscle to field stimulation whereas iso-OMPA (5 X 10(-6) to 5 X 10(-4) M) or BW 62c47 (5 X 10(-7) to 5 X 10(-5) M) do not. At a concentration of 10(-5) M, neostigmine. BW 62c47 and iso-OMPA respectively produced a 48, 50 and 68% inhibition of cholinesterase activity in homogenates of anococcygeus muscle. The ED50 for cholinesterase inhibition by neostigmine (1.4 X 10(-5) M) is approximately 15 fold greater than the ED50 for the augmentation of the response to field stimulation (9.5 X 10(-7) M). It is concluded that the action of neostigmine in augmenting the response of the rat anococcygeus muscle to field stimulation is not a consequence of cholinesterase inhibition even though stimulation of muscarinic receptors is implicated.
Smith
J A
JA
Spriggs
T L
TL
D000818:Animals; D002802:Cholinesterases / Q000032:analysis*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009132:Muscles / Q000187:drug effects* / Q000201:enzymology; D009388:Neostigmine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000187:drug effects
D011976:Receptors, Muscarinic; D009388:Neostigmine; D002802:Cholinesterases