Renal dopaminergic system activity in rat remnant kidney up to twenty-six weeks after surgery.
OBJECTIVE
In 3/4 nephrectomized (3/4nx) rats the renal dopaminergic system was suggested to be involved in the adaptive increase of sodium excretion two weeks after renal mass ablation. The aim of the present study was to evaluate the renal adaptations in sodium handling and renal dopaminergic system activity in 3/4nx rats up to twenty-six weeks after surgery.


METHODS
The rats were placed in metabolic cages for the collection of 24 h urine for evaluation of sodium, dopamine, dopamine precursor and metabolites. Blood pressure, aromatic L-amino acid decarboxylase (AADC) activity in proximal tubules and the effect of dopamine D(1) receptor selective antagonist (Sch-23390) on natriuresis was evaluated.


RESULTS
A time-dependent increase in both systolic and diastolic blood pressure was observed in 3/4nx rats, and this was accompanied by a decrease in urinary levels of dopamine and in renal AADC activity at twenty-six weeks after renal mass ablation. In contrast to what has been found two weeks after renal mass ablation, the natriuretic response to volume expansion was progressively reduced in 3/4nx rats at ten and twenty-six weeks after surgery and this was accompanied by insensitivity of natriuresis to Sch-23390.


CONCLUSIONS
In conclusion the renal dopaminergic system activity is compromised in 3/4nx rats in a time-dependent manner after renal mass ablation. It is suggested that this may contribute to compromise sodium excretion and increase blood pressure, in chronic renal insufficiency.
Moreira-Rodrigues
M
M
Nephrology Research and Development Unit, Faculty of Medicine, Portugal.
Sampaio-Maia
B
B
Pestana
M
M
D000222:Adaptation, Physiological; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D004298:Dopamine / Q000097:blood / Q000378:metabolism* / Q000652:urine; D006339:Heart Rate / Q000502:physiology; D007668:Kidney / Q000378:metabolism* / Q000502:physiology / Q000601:surgery*; D008297:Male; D009392:Nephrectomy; D009929:Organ Size / Q000502:physiology; D011188:Potassium / Q000097:blood / Q000652:urine; D011507:Proteinuria / Q000097:blood / Q000652:urine; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000097:blood / Q000652:urine
D012964:Sodium; D011188:Potassium; D004298:Dopamine