High sodium intake increases the urinary excretion of L-3,4-dihydroxyphenylalanine but fails to alter the urinary excretion of dopamine and amine metabolites in Wistar rats.
1. The present study has examined the daily urinary excretion of L-DOPA, dopamine and its metabolites (DOPAC, 3-MT and HVA) during normal salt (NS) and high salt(HS) diets. 2. Daily urinary excretion of L-DOPA, DA, DOPAC, 3-MT and HVA during the 4-day period of NS diet averaged, respectively, 7.6 +/- 0.4, 71 +/- 5, 217 +/- 22, 570 +/- 90 and 1217 +/- 110 nmol/kg/day. The slight increase in the urinary excretion of DA, DOPAC and 3-MT (16% to 42% increase), when rats were fed a HS diet, did not achieve statistical significance. 3. In contrast, the urinary levels of L-DOPA during the HS diet period (11 +/- 1 nmol/kg/day) were found to be significantly higher than during the NS diet period; the maximal increase in the urinary excretion of L-DOPA (93% increase) was observed in the first day and then a progressive decline was observed towards the end of the HS intake period. 4. During the first 5 days of the HS intake period, the urine output of noradrenaline (NA) was found to increase (27% to 83%) and then to progressively decline to baseline values (13.5 +/- 0.7 nmol/ kg/day). Urinary excretion of adrenaline (AD) during the HS intake period was found to increase (72% to 146%); the mean daily urinary excretion of AD during the NS diet period averaged 2.5 +/- 0.4 nmol/ kg/day. NS and DA contents in the kidney of rats on a NS diet were not significantly different from that of rats in a HS diet. 6. It is concluded that long-term HS intake in Wistar rats fail to change the urinary excretion of DA and of its metabolites (DOPAC, 3-MT and HVA). Furthermore, the discrepant profile in the urinary excretion of L-DOPA and DA during HS intake might be related to a reduction in the tubular uptake of the amino acid, rather than reflecting a decrease in its decarboxylation.
Vieira-Coelho
M A
MA
Institute of Pharmacology and Therapeutics, Faculty of Medicine, Porto, Portugal.
Pestana
M
M
Soares-da-Silva
P
P
D015102:3,4-Dihydroxyphenylacetic Acid / Q000652:urine; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003404:Creatinine / Q000652:urine; D004295:Dihydroxyphenylalanine / Q000097:blood / Q000652:urine*; D004298:Dopamine / Q000031:analogs & derivatives / Q000097:blood / Q000652:urine*; D006339:Heart Rate / Q000187:drug effects; D006719:Homovanillic Acid / Q000652:urine; D008297:Male; D009638:Norepinephrine / Q000652:urine; D011188:Potassium / Q000652:urine; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000652:urine; D012964:Sodium / Q000652:urine; D017673:Sodium Chloride, Dietary / Q000494:pharmacology*
D017673:Sodium Chloride, Dietary; D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; D004295:Dihydroxyphenylalanine; D012964:Sodium; D003404:Creatinine; C001746:3-methoxytyramine; D011188:Potassium; D004298:Dopamine; D009638:Norepinephrine; D006719:Homovanillic Acid