Receptor reserve at striatal dopamine receptors modulating the release of [3H]dopamine.
Electrically stimulated release of [3H]dopamine [( 3H]DA) in slices of rat striatum was dose dependently inhibited by apomorphine (67% maximal inhibition) with an EC50 of 17 nM. DA receptor inactivation with N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ; 0.5 and 2 mg/kg) dose dependently shifted the ED50 for apomorphine to the right and reduced the maximal inhibition obtained. Analysis of the results yielded a hyperbolic plot of receptor occupancy vs. response, indicating that a large receptor reserve (50-60%) for apomorphine exists at the DA autoreceptor in rat striatum mediating inhibition of transmitter release.
Yokoo
H
H
New York University Medical Center, Neurochemistry Research Laboratories 10016.
Goldstein
M
M
Meller
E
E
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D003342:Corpus Striatum / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D011804:Quinolines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000502:physiology*
D011804:Quinolines; D011954:Receptors, Dopamine; C000470:EEDQ; D001058:Apomorphine; D004298:Dopamine