Premium
Regulation of Ca2+‐Activated Cl− Channels by Calcineurin and PP1 in Rabbit Pulmonary Arterial Smooth Muscle Cells
Author(s) -
Ayon Ramon Jose,
Sones William,
Sanguinetti Amy,
Greenwood Iain A,
Leblanc Normand
Publication year - 2007
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.21.6.a1156-c
Subject(s) - okadaic acid , phosphatase , calcineurin , chemistry , myocyte , calcium , medicine , endocrinology , phosphorylation , biochemistry , transplantation
Calcium‐activated chloride currents (I Cl(Ca) ) represent a major excitatory mechanism in vascular smooth muscle cells (SMCs). Recent work by our group provided evidence for modulation of I Cl(Ca) by CaMKII and Calcineurin (CaN) in arterial SMCs. The aim of this study was to determine the role of Ser/Thr phosphatases PP1 and PP2A in regulation of I Cl(Ca) in rabbit pulmonary artery (PA) myocytes. I Cl(Ca) was elicited by clamping internal Ca 2+ to 500 nM. In cells dialyzed with 3 mM ATP, I Cl(Ca) ran down ~ 80% after 20 min. Cell dialysis with an ATP‐free pipette solution attenuated the rundown followed by complete recovery of the current eventually exceeding the initial level. Okadaic acid (OA), a non‐selective PP1/PP2A inhibitor, dose‐dependently attenuated (0.5 – 30 nM) the recovery of I Cl(Ca) in the absence of internal ATP. In contrast, the highly specific PP2A inhibitor Fostriecin (30–150 nM; IC 50 for PP2A = 3 nM; IC 50 for PP1 = 131 μM) had no effect on the rundown and recovery of I Cl(Ca) with 0 ATP. Finally, cell dialysis with the highly specific peptide inhibitor of PP1 NIPP‐1 (100 pM; IC 50 ≈ 1–10 pM) produced similar effects to OA on current rundown and recovery, suggesting that PP1 may be involved in the up‐regulation of I Cl(Ca) seen with 0 ATP. These results are consistent with the hypothesis that I Cl(Ca) in rabbit PA myocytes is regulated by CaN and PP1 but not PP2A. [NHLBI: 1 RO1 HL075477‐01‐A2 (NL); COBRE: NCRR 5 P20 RR15581 (NL)]