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The BK channel in the renal adaptation to chronic metabolic acidosis (CMA) in cortical collecting duct (CCD)
Author(s) -
Schreck Carlos M,
Zavilowitz Beth,
Satlin Lisa M
Publication year - 2013
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.27.1_supplement.730.8
Subject(s) - chemistry , intercalated cell , intracellular ph , endocrinology , iberiotoxin , metabolic acidosis , medicine , intracellular , biochemistry , potassium , cell , organic chemistry
The density of BK channels in CCD intercalated cells (ICs) exceeds that in principal cells. We hypothesized that this channel is upregulated in acid secreting α‐ICs during CMA to recycle K for a luminal H/K‐ATPase. H pump activity was measured in α‐ICs in BCECF‐loaded microperfused CCDs from CMA rabbits (75 mM NH 4 Cl in drinking water × 5–7 d) as the rate (pH U/min) of Na‐independent pHi recovery from an acute NH 4 Cl prepulse in the absence (H‐ATPase) and then presence (H/K‐ATPase) of luminal ( L ) K, in the absence (control) or presence of iberiotoxin (IBX), a BK channel inhibitor. The effect of IBX on pHi was also studied in the presence of bath EIPA and L bafilomycin (Baf) to inhibit Na/H exchange and the H‐ATPase, respectively.Nadir pHi H‐ATPase activity pHi H/K‐ATPase activityControl (n=7) 6.64 ± 0.05 0.057 ± 0.030 6.89 ± 0.08 0.009 ± 0.011L IBX (n=4) 6.68 ± 0.05 0.043 ± 0.040 6.87 ± 0.10 0.000 ± 0.008In 5 CCDs, pHi fell from 7.36 ± 0.10 to 7.16 ± 0.06 with EIPA (p<0.05) but was further unchanged by L Baf or IBX. The findings that IBX did not significantly alter (i) H‐ or H/K‐ATPase‐mediated recovery from an acute acid load or (ii) pHi in CCDs from CMA animals suggests that the channel does not participate in the adaptation of α‐ICs to CMA.