Renal Dopamine and Changes in Dopamine Receptor Ligand Binding During High Sodium Intake

Abstract

This study was designed to measure changes in plasma levels of atrial natriuretic peptides (ANP), urine volume (UV), urinary excretion of dopamine (U_DAV) and sodium (U_NaV), and dopamine (DA) receptor affinity (K_d) and binding sites (B_max) in kidneys of rats drinking normal saline for a period of 7 days. The saline intake significantly increased UV, U_naV, plasma ANP, U_naV, and its primary metabolite dihydroxyphenyl acetic acid (DOPAC) for the period of 7 days. B_max increased significantly 1 day after the initiation of saline intake, however, the increase appeared to be transient since measurements of B_max made after 7 days of saline intake were not significantly different from the control group. No changes in K_d were observed. These results indicate that renal DA contributes to maintenance of Na balance during increased Na intake and that renal DA receptors undergo transient changes during this period.

Key Words:

• dopamine
• ANP
• dopamine receptors
• renal function