ENaC activity in the cortical collecting duct of HKα1H+,K+-ATPase knockout mice is uncoupled from Na+intake.
Modulation of the epithelial Na+channel (ENaC) activity in the collecting duct (CD) is an important mechanism for normal Na+homeostasis. ENaC activity is inversely related to dietary Na+intake, in part due to inhibitory paracrine purinergic regulation. Evidence suggests that H+,K+-ATPase activity in the CD also influences Na+excretion. We hypothesized that renal H+,K+-ATPases affect Na+reabsorption by the CD by modulating ENaC activity. ENaC activity in HKα1H+,K+-ATPase knockout (HKα1-/-) mice was uncoupled from Na+intake. ENaC activity on a high-Na+diet was greater in the HKα1-/-mice than in WT mice. Moreover, dietary Na+content did not modulate ENaC activity in the HKα1-/-mice as it did in WT mice. Purinergic regulation of ENaC was abnormal in HKα1-/-mice. In contrast to WT mice, where urinary [ATP] was proportional to dietary Na+intake, urinary [ATP] did not increase in response to a high-Na+diet in the HKα1-/-mice and was significantly lower than in the WT mice. HKα1-/-mice fed a high-Na+diet had greater Na+retention than WT mice and had an impaired dipsogenic response. These results suggest an important role for the HKα1subunit in the regulation of purinergic signaling in the CD. They are also consistent with HKα1-containing H+,K+-ATPases as important components for the proper regulation of Na+balance and the dipsogenic response to a high-salt diet. Such observations suggest a previously unrecognized element in Na+regulation in the CD.
Department of Physiology, University of Texas Health Science Center, San Antonio, Texas.
Elena
E
Mironova
North Florida/South Georgia Veterans Health Service, Gainesville, Florida; and.|Department of Medicine, University of Florida, Gainesville, Florida.
I Jeanette
IJ
Lynch
Department of Physiology, University of Texas Health Science Center, San Antonio, Texas.
Jonathan M
JM
Berman
North Florida/South Georgia Veterans Health Service, Gainesville, Florida; and.|Department of Medicine, University of Florida, Gainesville, Florida.
Michelle L
ML
Gumz
Department of Physiology, University of Texas Health Science Center, San Antonio, Texas.
James D
JD
Stockand
North Florida/South Georgia Veterans Health Service, Gainesville, Florida; and cswingo@ufl.edu.|Department of Medicine, University of Florida, Gainesville, Florida.
Charles S
CS
Wingo
D000255:Adenosine Triphosphate / Q000652:urine; D000450:Aldosterone / Q000097:blood; D000818:Animals; D053503:Epithelial Sodium Channels / Q000378:metabolism*; D005838:Genotype; D017506:H(+)-K(+)-Exchanging ATPase / Q000172:deficiency* / Q000235:genetics; D006706:Homeostasis; D006955:Hypernatremia / Q000097:blood / Q000201:enzymology / Q000235:genetics / Q000652:urine; D007685:Kidney Tubules, Collecting / Q000201:enzymology*; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010641:Phenotype; D065667:Renal Elimination; D065608:Renal Reabsorption; D015398:Signal Transduction; D012982:Sodium, Dietary / Q000378:metabolism*; D013997:Time Factors; D014667:Vasopressins / Q000097:blood
D053503:Epithelial Sodium Channels; D012982:Sodium, Dietary; D014667:Vasopressins; D000450:Aldosterone; D000255:Adenosine Triphosphate; D017506:H(+)-K(+)-Exchanging ATPase
ENaC; purinergic signaling; regulated epithelial Na channel; renal