Table 1.
In vivo experimental protocol.
Table 2.
Renal functional parameters of control and experimental groups.
Table 3.
Hemodynamic parameters of control and experimental groups.
Fig 1.
In vivo inhibition of OCTs with D-22 and its effects on Na+, K+-ATPase activity in the presence of dopamine (DA) and ANP plus DA.
*p<0.001 vs Control/P+T; **p<0.05 vs DA; ***p<0.05 vs ANP; #p<0.05 vs ANP plus DA; $p<0.05 vs D-22.
Fig 2.
Effects of exogenous dopamine, ANP and D-22 on dopamine urinary levels.
*p<0.05 vs Control; **p<0.05 vs DA; #p<0.05 vs ANP plus DA.
Fig 3.
A, B and C. Western blot analysis of OCT-1 (A), OCT-2 (B) and OCT-3 (C) in renal cortex: Effects of MAO and COMT inhibition by pargyline and tolcapone (P+T) and ANP infusion on OCT-1 (A), OCT-2 (B) and OCT-3 (C) protein expression in membrane preparations from renal cortex.
Histograms illustrate the values of protein expression of OCTs in each group, normalized to GAPDH expression.
Fig 4.
Western blot analysis of D1R in renal cortex: Effects of MAO and COMT inhibition by pargyline and tolcapone (P+T) and ANP infusion on D1R expression in membrane preparations from renal cortex.
Histograms illustrate the values of protein expression of D1R in each group, normalized to GAPDH expression.
Fig 5.
Effects of ANP, D-22, anantin and KT 5823 on 3H-dopamine uptake.
*p<0.05 vs Control; ***p<0.01 vs ANP; ##p<0.05 vs ANP.
Fig 6.
Schematic representation of the mechanism by which ANP could enhance dopamine tubular transport in proximal tubule cells, by stimulation of organic cationic transporters.
A: under basal conditions, exogenous dopamine is carried by OCTs located at the basolateral membrane and uptaken from circulation and interstitium by the proximal tubular cells. B: Once inside the tubular cell, dopamine can reach the tubular lumen through the OCTNs located at the apical membrane. Atrial natriuretic peptide inhibits Na+, K+-ATPase activity through stimulation of NPR-A receptors, cGMP and PKG. C: ANP enhances dopamine tubular transport by OCTs, stimulating its specific activity, and increasing dopamine concentration at the luminal side. The simultaneous inhibition of Na+, K+-ATPase activity by ANP and dopamine promotes a greater natriuretic response. OCTs: organic cationic transporters. OCTNs: carnitine/organic cationic transporters. Black circles: dopamine; gray triangles: ANP. Full arrows: stimulation; dot arrows: inhibition; gray arrow with?: hypothetical mechanism.