Role of renal catecholamines in the control of sodium and water excretion: lack of natriuresis by endogenous dopamine in the rat kidney.
The physiological role of dopamine in renal Na and water excretion was studied in rats treated with L-3,4-dihydroxyphenylalanine (L-DOPA), haloperidol or 6-hydroxydopamine for 1 week. Daily-pooled urine samples, plasma, and kidneys were obtained from the experimental groups and untreated controls. Urinary dopamine was markedly elevated in L-DOPA-treated and transiently decreased in haloperidol-treated rats. Urinary epinephrine, but not norepinephrine was increased in the L-DOPA and haloperidol groups. However, there was no significant difference in urine volume, urinary Na, urinary K, plasma Na and K levels between the experimental groups and controls, except for 6-hydroxydopamine-treated rats. They showed a definite increase in urinary volume, Na, K and aldosterone excretion, whereas the renal norepinephrine and epinephrine content was reduced. Urinary cAMP and Na-K ATPase activity were also similar in all groups, whereas renal cAMP content and aromatic amino acid decarboxylase activity were significantly increased in the L-DOPA and haloperidol groups, suggesting an activated catecholamine synthesis in the kidney. [3H]haloperidol binding was also increased by the L-DOPA and 6-hydroxydopamine administration, but the half maximal displacement dose was similar in all groups (6.4 x 10(-9)mol/l), indicating an increase in the number of dopamine binding sites. These results indicate that 1) in contrast to the pharmacological effect of dopamine, locally-formed dopamine has no direct natriuretic action in the kidney; 2) an enhanced production of dopamine in the kidney does not suppress aldosterone secretion.(ABSTRACT TRUNCATED AT 250 WORDS)
Sato
T
T
Department of Paediatrics, School of Medicine, Kanazawa University, Japan.
Minami
S
S
Okabe
T
T
Igarashi
N
N
D000818:Animals; D001834:Body Water / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D004837:Epinephrine / Q000378:metabolism*; D006220:Haloperidol / Q000494:pharmacology; D006892:Hydroxydopamines / Q000494:pharmacology; D007668:Kidney / Q000378:metabolism*; D007980:Levodopa / Q000494:pharmacology; D009318:Natriuresis / Q000187:drug effects*; D009638:Norepinephrine / Q000378:metabolism*; D016627:Oxidopamine; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects*; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D006892:Hydroxydopamines; D011954:Receptors, Dopamine; D007980:Levodopa; D016627:Oxidopamine; D012964:Sodium; D000242:Cyclic AMP; D000254:Sodium-Potassium-Exchanging ATPase; D006220:Haloperidol; D009638:Norepinephrine; D004837:Epinephrine