TY - JOUR
T1 - Renal fluid and electrolyte handling in BKCa-β1-/- mice
AU - Pluznick, Jennifer L.
AU - Wei, Peilin
AU - Carmines, Pamela K.
AU - Sansom, Steven C.
PY - 2003/6/1
Y1 - 2003/6/1
N2 - Large-conductance Ca2+-activated K+ channels (BKCa) are composed of pore-forming α-subunits and one of four accessory β-subunits. The β1subunit, found predominantly in smooth muscle, modulates the Ca2+ sensitivity and pharmacological properties of BKCa. BKCa-β1 null mice (Mβ1-/-) are moderately hypertensive, consistent with the role of BKCa in modulating intrinsic vascular tone. Because BKCa are present in various renal cells including the mesangium and cortical collecting ducts, we determined whether fluid or electrolyte excretion was impaired in Mβ1-/- under euvolemic, volume-expanded, or high-salt diet conditions. Under euvolemic conditions, no differences in renal function were found between Mβ1-/- and Mβ1+/+. However, glomerular filtration rate (GFR) and fractional K+ excretion were significantly impaired in Mβ1-/- in response to acute volume expansion. In contrast, Mβ1-/- exhibited enhanced Na+ excretion and fractional Na+ excretion responses to acute volume expansion. Differences in renal function between Mβ1+/+ and Mβ1-/- were not observed when chronically treated with a high-salt diet. These observations indicate that the β1-subunit of BKCa contributes to the increased GFR that accompanies an acute salt and volume load and raises the possibility that it is also involved in regulating K+ excretion under these conditions.
AB - Large-conductance Ca2+-activated K+ channels (BKCa) are composed of pore-forming α-subunits and one of four accessory β-subunits. The β1subunit, found predominantly in smooth muscle, modulates the Ca2+ sensitivity and pharmacological properties of BKCa. BKCa-β1 null mice (Mβ1-/-) are moderately hypertensive, consistent with the role of BKCa in modulating intrinsic vascular tone. Because BKCa are present in various renal cells including the mesangium and cortical collecting ducts, we determined whether fluid or electrolyte excretion was impaired in Mβ1-/- under euvolemic, volume-expanded, or high-salt diet conditions. Under euvolemic conditions, no differences in renal function were found between Mβ1-/- and Mβ1+/+. However, glomerular filtration rate (GFR) and fractional K+ excretion were significantly impaired in Mβ1-/- in response to acute volume expansion. In contrast, Mβ1-/- exhibited enhanced Na+ excretion and fractional Na+ excretion responses to acute volume expansion. Differences in renal function between Mβ1+/+ and Mβ1-/- were not observed when chronically treated with a high-salt diet. These observations indicate that the β1-subunit of BKCa contributes to the increased GFR that accompanies an acute salt and volume load and raises the possibility that it is also involved in regulating K+ excretion under these conditions.
KW - Glomerular filtration rate
KW - Large-conductance, calcium-activated potassium channels
KW - Maxi K channel
KW - Potassium excretion
KW - Volume expansion
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U2 - 10.1152/ajprenal.00010.2003
DO - 10.1152/ajprenal.00010.2003
M3 - Article
C2 - 12620927
AN - SCOPUS:0038284837
SN - 1931-857X
VL - 284
SP - F1274-F1279
JO - American Journal of Physiology - Renal Physiology
JF - American Journal of Physiology - Renal Physiology
IS - 6 53-6
ER -