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K + homeostasis is maintained with knockdown of big‐conductance K + channel in principal cells of connecting tubule/collecting duct
Author(s) -
Rieg Timo,
Lukowski Robert,
Dominguez Jessica,
Sharik Meaghen,
Ruth Peter,
Vallon Volker
Publication year - 2012
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.26.1_supplement.867.4
Subject(s) - bk channel , chemistry , homeostasis , endocrinology , medicine , distal convoluted tubule , kidney , reabsorption , potassium channel
Big‐conductance K + (BK) channels are expressed in principal cells (PC) and intercalated cells of the kidney and contribute to K + homeostasis and flow‐induced K + secretion. To define the role of BK channels in PC, we generated mice with conditionally inactivated BK channels in PC of the connecting tubule/collecting duct (AQP2:Cre; BK loxloxCre ). Cre negative BK loxlox mice served as controls (Con). On standard diet (Teklad 7001), Plasma Na + (Con vs BK loxloxCre : 150±0.4 vs 150±0.4 mmol/l), K + (4.4±0.1 vs 4.3±0.1 mmol/l), pH (7.4±0.04 vs 7.4±0.04), and hematocrit (49±0.4 vs 50±0.5 %) were not different between genotypes. Systolic blood pressure and heart rate, determined by tail cuff, were comparable between genotypes (Con: 113±2 mmHg and 623±16 min −1 , BK loxloxCre : 116±2 mmHg and 647±13 min −1 ). Spontaneous urine collections showed similar urine osmolality in Con and BK loxloxCre (2041±87 vs 1950±85 mmol/kg). However, urinary K + /Na + ratio was significantly higher in BK loxloxCre vs Con (1.49±0.07 vs. 1.17±0.07, P<0.05 ) due to lower urinary Na + /creatinine (crea) in BK loxloxCre vs Con (21.7±1.3 vs. 25.4±1.1, mmol/mmol P<0.05 ), while urinary K + /crea was not different (31.9±1.8 vs 29.6±1.6 mmol/mmol). Our data indicate that under control diet conditional knockdown of BK channels in PC of the connecting tubule/collecting duct reduces Na + excretion while K + homeostasis is maintained.