Abstract
Renal dopamine has been proposed to be involved in the regulation of glomerular filtration rate (GFR). Because inhibition of dopamine D2 receptors abolishes the renal hyperfiltration due to amino acid load, we tested the hypothesis that pharmacological activation of D2-like receptors mimicked this renal response. In anesthetized rats, quinpirole (0.3 μg · 100 g−1 · min−1), an agonist for receptors of the D2-like family, caused an increase in GFR by 20 ± 2%, which corresponded to that provoked by infusion of an 10% amino acid solution. The D2 receptor antagonist S(−)-sulpiride that acts both centrally and peripherally completely abolished the renal hemodynamic response to quinpirole and to amino acids whereas domperidone, a peripherally acting D2receptor antagonist, inhibited this hyperfiltration only in part. Urinary dopamine excretion increased in response to amino acid infusion whether GFR increased or not. We conclude that, in anesthetized rats, dopamine D2 receptors contribute to the amino acid-induced hyperfiltration and that both central and peripheral receptors might be involved, whereas dopamine excreted into the urine does not appear to play a functional role in this renal hemodynamic response.
Footnotes
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Send reprint requests to: Dr. G. Luippold, Department of Pharmacology, University of Tübingen, Wilhelmstrasse 56, D-72074 Tübingen, Germany.
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↵1 This study was supported by grants from the Federal Ministry of Education and Research (BMBF 01EC0405) and by the Deutsche Forschungsgemeinschaft (DFG Mu 1297/1-1). G. L. is a fellow of the Interdisciplinary Clinical Research Center (IKFZ 01KS 9602) Tübingen.
- Abbreviations:
- AA
- amino acid
- CON
- time controls
- CP
- clearance period
- DOM
- domperidone
- FENa
- fractional urinary sodium excretion
- HR
- heart rate
- Hct
- hematocrit
- L-DOPA
- L-3,4-dihydroxyphenylalanine
- MAP
- mean arterial blood pressure
- NaPlasma
- sodium plasma concentration
- QP
- quinpirole
- SUL
- S(−)-sulpiride
- UNaV
- total urinary sodium excretion
- UV
- urinary flow rate
- UDAV
- urinary dopamine excretion
- VHC
- vehicle controls
- PE
- polyethylene
- Received January 2, 1998.
- Accepted May 1, 1998.
- The American Society for Pharmacology and Experimental Therapeutics
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