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In vivo determination of the renal activity of the epithelial sodium channel (ENaC) using benzamil natriuresis in male (M) and female (F) mice infused with angiotensin II (Ang II)
Author(s) -
Li Lijun,
Tiwari Swasti,
Mulroney Susan,
Sandberg Kathryn,
Ecelbarger Carolyn M.
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.1024.30
Subject(s) - natriuresis , epithelial sodium channel , endocrinology , medicine , saline , chemistry , angiotensin ii , excretion , renin–angiotensin system , antagonist , sodium , blood pressure , receptor , organic chemistry
We recently showed sex differences on immunoblots for ENaC subunits with Ang II infusion. To determine whether these protein changes were associated with altered ENaC activity, in Study 1, M and F mice (MF‐1 strain) were infused with Ang II by osmotic minipump (800 ng/kg·bw/min) or received a sham surgery (n = 5/sex/treatment). After 7 days, mice were anesthetized and infused via a jugular catheter with saline (2% body weight/hour), then saline plus benzamil (ENaC antagonist) for 2‐consecutive, 20‐minute periods. Urine was collected from the catheterized bladder. Period 1 natriuresis (response to the infusion) was not different between groups. Period 2 natriuresis (index of ENaC activity) was increased by Ang II, but only in male mice (% of sex respective control group): 141 (MA) and 104 (FA). In Study 2, control M and F MF‐1 mice were treated intraperitoneally with benzamil @1.4 mg/kg·bw in the conscious state and urine collected for 4 hours in metabolic cages. No sex differences were observed in the control state (mmol Na/kg·bw/4 hours): 2.24 ± 0.27 (M) vs 2.47 ± 0.26 (F); however, when Ang II was infused into the same mice (in the subsequent week) only M mice showed a positive increase (Δ mmol Na/kg·bw/4 hours): +1.70 ± 1.79 (M) vs −1.26 ± 0.31 (F). Overall, Ang II increased natriuretic response to benzamil to a greater extent in the males suggesting greater ENaC activity, which may provide insight on therapies for both sexes.