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Mitogen‐Activated Protein Kinases (MAPK) Inhibit the Ca2+‐Dependent Big Conductance K Channels (BK) In the CCD
Author(s) -
Li Dimin,
Wang Zhijian,
Sun Peng,
Wang WenHui
Publication year - 2006
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.20.4.a799-a
Subject(s) - bk channel , mapk/erk pathway , chemistry , biophysics , patch clamp , conductance , p38 mitogen activated protein kinases , pipette , kinase , protein kinase a , microbiology and biotechnology , potassium channel , biochemistry , biology , physics , receptor , condensed matter physics
We used the patch‐clamp technique to study the role of MAPK in the regulation of BK channels in the CCD. Under control conditions, we identified BK channels in 4 out of 50 patches (8%) in principal cells (PC) and 7 out of 25 patches (28%) in intercalated cells (IC). The channel conductance was 135–150 pS and NPo was 0.01 in cell‐attached patches. In inside out patches channel conductance increased to 170–180 pS in a symmetrical 140 mM KCl bath/pipette solution. The channel open probability of the BK increased to 0.6 when the bath Ca2+ concentration was 10 μM Ca2+ and decreased to 0 by removing Ca2+ from the bath solution facing the cytosolic side. The probability of finding BK channels in PC increased by adding ionmycin and we observed BK channels in 3 patches out of 8 patches performed on PC. Moreover, the probability of finding the BK channels in PC increased after inhibition of P38 MAPK from 8% to 20% (3 patches have BK channel activity out of a total of 15 patches) and to 30% by inhibition of both Erk and P38 MAPK (5 out of 18 cells). Moreover, inhibition of both MAPK increased NPo from 0.01 to 0.30. Although inhibition of P38 and Erk MAPK did not significantly increase the probability of finding the BK channels in the IC, inhibition of MAPK increased NPo of BK in IC from 0.02 to 0.17. Thus, we conclude that maxi K channels are expressed in PC and IC cells and that P38 and Erk MAPK play an important role in the regulation of BK channel activity in both PC and IC of the CCD.