Differential inhibition of secretagogue-stimulated sodium uptake in adrenal chromaffin cells by activation of D4 and D5 dopamine receptors.
J Neurochem
; 67(5): 1960-4, 1996 Nov.
Article
in En
| MEDLINE
| ID: mdl-8863501
ABSTRACT
Recent studies have demonstrated that D1-selective and D2-selective dopamine receptor agonists inhibit catecholamine secretion and Ca2+ uptake into bovine adrenal chromaffin cells by receptor subtypes that we have identified by PCR as D5, a member of the D1-like dopamine receptor subfamily, and D4, a member of the D2-like dopamine receptor subfamily. The purpose of this study was to determine whether activation of D5 or D4 receptors inhibits influx of Na+, which could explain inhibition of secretion and Ca2+ uptake by dopamine agonists. D1-selective agonists preferentially inhibited both dimethylphenylpiperazinium- (DMPP) and veratridine-stimulated 22Na+ influx into chromaffin cells. The D1-selective agonists chloro-APB hydrobromide (CI-APB; 100 microM) and SKF-38393 (< 00 microM) inhibited DMPP-stimulated Na+ uptake by 87.5 +/- 2.3 and 59.7 +/- 4.5%, respectively, whereas the D2-selective agonist bromocriptine (100 microM) inhibited Na+ uptake by only 22.9 +/- 5.0%. Veratridine-stimulated Na+ uptake was inhibited 95.1 +/- 3.2 and 25.7 +/- 4.7% by 100 microM CI-APB or bromocriptine, respectively. The effect of CI-APB was concentration dependent. A similar IC50 (approximately 18 microM) for inhibition of both DMPP- and veratridine-stimulated Na+ uptake was obtained. The addition of 8-bromo-cyclic AMP (1 mM) had no effect on either DMPP- or veratridine-stimulated Na+ uptake. These observations suggest that D1-selective agonists are inhibiting secretagogue-stimulated Na+ uptake in a cyclic AMP-independent manner.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Sodium
/
Receptors, Dopamine D2
/
Receptors, Dopamine D1
/
Chromaffin Cells
Limits:
Animals
Language:
En
Journal:
J Neurochem
Year:
1996
Document type:
Article
Affiliation country:
United States