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Differences in phosphorylation‐mediated K+ channel regulation between vascular smooth muscle cells from cremaster and cerebral resistance vessels
Author(s) -
Yang Yan,
Braun Andrew P,
Davis Michael J,
Hill Michael A
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.870.35
Subject(s) - forskolin , vascular smooth muscle , medicine , endocrinology , phosphorylation , protein kinase a , chemistry , patch clamp , basal (medicine) , potassium channel , biology , biophysics , biochemistry , electrophysiology , smooth muscle , stimulation , insulin
The activity of maxi K+ channels (BKCa) differs in vascular smooth muscle cells (VSMC) from cremaster muscle (CM) and cerebral (CER) resistance arteries. As BKCa are regulated by cyclic nucleotide‐dependent phosphorylation, we examined channel responses to the cAMP stimulant forskolin, dependence on PKA and PKG, and differences in basal phoshorylation levels. Isolated VSMCs were studied using whole cell patch clamp. Forskolin (10– 30 μM) increased whole cell K+ current in both preparations, increasing current at +70 mV by 170.2 ± 1.2 % in CER VSMCs and 136.1 ± 2.5 % in CM VSMCs. Forskolin‐induced K+ currents showed weak sensitivity to the PKA blocker, KT5720 (0.3 μM), while being abolished by the PKG inhibitor, KT5823 (0.3 μM). Basal phosphorylation was apparent as KT5823 reduced basal K+ current and STOCs in both cell preparations. To further determine contributions from basal phoshorylation, VSMCs were dialyzed with alkaline phosphatase (AP; 350U/ml) via the patch pipette. AP reduced K+ current at +70 mV by 49.3 ± 0.9 % in CER VSMCs compared to 28.6 ± 2.1 % in VSMCs from CM and prevented a further reduction in current by KT5823. The data suggest that K+ conductance can be modulated by cAMP in both preparations by mechanisms involving cross‐talk to PKG. Further, BKCa in CER VSMCs may exhibit a higher level of basal phosphorylation, which contributes to their higher basal activity relative to VSMCs from CM. (Supp NIH HL092241)