Renal dopaminergic defect in C57Bl/6J mice.
The C57Bl/6J mouse strain, the genetic background of many transgenic and gene knockout models, is salt sensitive and resistant to renal injury. We tested the hypothesis that renal dopaminergic function is defective in C57Bl/6J mice. On normal NaCl (0.8%, 1 wk) diet, anesthetized and conscious (telemetry) blood pressures were similar in C57Bl/6J and SJL/J mice. High NaCl (6%, 1 wk) increased blood pressure (approximately 30%) in C57Bl/6J but not in SJL/J mice and urinary dopamine to greater extent in SJL/J than in C57Bl/6J mice. Absolute and fractional sodium excretions were lower in SJL/J than in C57Bl/6J mice. The blood pressure-natriuresis plot was shifted to the right in C57Bl/6J mice. Renal expressions of D(1)-like (D(1)R and D(5)R) and angiotensin II AT(1) receptors were similar on normal salt, but high salt increased D(5)R only in C57Bl/6J. GRK4 expression was lower on normal but higher on high salt in C57Bl/6J than in SJL/J mice. Salt increased the excretion of microalbumin and 8-isoprostane (oxidative stress marker) and the degree of renal injury to a greater extent in SJL/J than in C57Bl/6J mice. A D(1)-like receptor agonist increased sodium excretion whereas a D(1)-like receptor antagonist decreased sodium excretion in SJL/J but not in C57Bl/6J mice. In contrast, parathyroid hormone had a similar natriuretic effect in both strains. These results show that defective D(1)-like receptor function is a major cause of salt sensitivity in C57Bl/6J mice, decreased renal dopamine production might also contribute. The relative resistance to renal injury of C57Bl/6J may be a consequence of decreased production of reactive oxygen species.
Escano
Crisanto S
CS
Children's National Medical Center, Center for Molecular Physiology Research, Department of Pediatrics, George Washington School of Medicine and Health Sciences, Washington, DC, USA.
Armando
Ines
I
Wang
Xiaoyan
X
Asico
Laureano D
LD
Pascua
Annabelle
A
Yang
Yu
Y
Wang
Zheng
Z
Lau
Yuen-Sum
YS
Jose
Pedro A
PA
D000419:Albuminuria / Q000209:etiology / Q000378:metabolism; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000235:genetics; D015237:Dinoprost / Q000031:analogs & derivatives / Q000652:urine; D004298:Dopamine / Q000652:urine*; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D018818:Fenoldopam / Q000494:pharmacology; D005838:Genotype; D007668:Kidney / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL / Q000235:genetics / Q000378:metabolism*; D009318:Natriuresis / Q000187:drug effects / Q000235:genetics; D018384:Oxidative Stress; D010281:Parathyroid Hormone / Q000378:metabolism; D010641:Phenotype; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D017447:Receptors, Dopamine D1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D050641:Receptors, Dopamine D5 / Q000378:metabolism; D017673:Sodium Chloride, Dietary / Q000009:adverse effects / Q000378:metabolism*; D013045:Species Specificity
D001552:Benzazepines; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D010281:Parathyroid Hormone; D044140:Receptor, Angiotensin, Type 1; D017447:Receptors, Dopamine D1; C534628:SCH 23390; D017673:Sodium Chloride, Dietary; D050641:Receptors, Dopamine D5; C075750:8-epi-prostaglandin F2alpha; D015237:Dinoprost; D018818:Fenoldopam; D004298:Dopamine