Dopamine inhibits AVP-dependent Na+ transport and water permeability in rat CCD via a D4-like receptor
Sun, D.; Schafer, J.A.
American Journal of Physiology 271(2 Pt 2): F391-F400
1996
ISSN/ISBN: 0002-9513 PMID: 8770171 Document Number: 456258
We studied the receptor responsible for dopamine action in isolated perfused cortical collecting ducts (CCD) from rats treated with deoxycorticosterone. (Critical experiments were repeated in CCD from untreated rats with the same results.) At doses gtoreq 1 mu-M, dopamine inhibited arginine vasopressin (AVP)-dependent Na+ and water transport (measured by the unidirectional lumen-to-bath 22Na+ flux and the transepithelial voltage) and osmotic water permeability (P-f). The effects of dopamine were not reversed by the dopamine-1 (D-1) antagonist SCH-23390, and no inhibition was produced by the D-1 agonists fenoldopam or SKF-81247. When Na+ transport and P-f were stimulated with 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate plus 3-isobutyl-1-methylxanthine, dopamine did not inhibit, suggesting a "D-2-type" receptor. However, the D-2 agonist quinpirole had no effect on the AVP-dependent transepithelial voltage (V-T), and the D-2 and D-3 antagonists domperidone and pimozide did not reverse dopamine inhibition of VT. The only agent tested that reversed the effects of dopamine was the D-4-specific antagonist clozapine. We conclude that dopamine inhibition of salt and water transport in the CCD is mediated by a D-4-like receptor.