ISSN:
1573-6903
Keywords:
Bromoacetamidoprocaine
;
procaine
;
muscarinic
;
nicotinic
;
local anesthetic
;
rat hyperactivity
;
affinity ligand
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract This study describes the synthesis, receptor binding characteristics, and some behavioral effects of p-bromoacetamidoprocaine (BAP), a new affinity ligand for brain muscarinic and nicotinic cholinergic receptors. The reversible binding of [3H]QNB to rat brain membranes was inhibited in a concentration dependent and saturable manner by both procaine and BAP, with Ki values of 4×10−6 and 3×10−7 M, respectively, and complete inhibition at 1×10−5 M. Both procaine and BAP, although at much concentrations, inhibited the binding of [3H]methylcarbamylcholine in a concentration dependent manner, with Ki values of 5×10−5 and 1×10−5 M, respectively, and complete inhibition for both at 1×10−3 M. Plots of the % irreversible inhibition of [3H]QNB, [3H]nicotine, and [3H]MCC vs [BAP] yielded Ki values of 7×10−8, 1×10−4, and 6×10−5 M, respectively. In behavioral studies BAP was able to antagonize the QNB-induced hyperactivity in mice; however, BAP did not appear to alter nicotine-induced seizure activity or other behavioral effects in mice. A plot of the time course of inhibition by BAP for [3H]QNB binding revealed that the inhibition was almost complete within 10 min exposure at 37°. The findings indicate that BAP is a useful affinity ligand for examining the biochemical and functional characteristics of brain cholinergic receptors, particularly the muscarinic which has an affinity near the nM concentration range.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00966666
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