TY - JOUR
T1 - Protein phosphatase 2A and Ca2+-activated K+ channels contribute to 11,12-epoxyeicosatrienoic acid analog mediated mesenteric arterial relaxation
AU - Dimitropoulou, Christiana
AU - West, Lashondra
AU - Field, Mary B.
AU - White, Richard E.
AU - Reddy, L. Manmohan
AU - Falck, J R
AU - Imig, John D.
N1 - Funding Information:
This work was supported by the National Institutes of Health (NIH) grants HL-59699, DK38226 and an American Heart Association Established Investigator Award to J.D. Imig. NIH grant HL07389 to R.E. White. NIH grant GM31278 and the Robert A. Welch Foundation to J.R. Falck.
PY - 2007/2
Y1 - 2007/2
N2 - Epoxyeicosatrienoic acids (EETs) are considered to be endothelium-derived hyperpolarizing factors, and are potent activators of the large-conductance, Ca2+-activated K+ (BKCa) channel in vascular smooth muscle. Here, we investigate the signal transduction pathway involved in the activation of BKCa channels by 11,12-EET and 11,12-EET stable analogs in rat mesenteric vascular smooth muscle cells. 11,12-EET and the 11,12-EET analogs, 11-nonyloxy-undec-8(Z)-enoic acid (11,12-ether-EET-8-ZE), 11-(9-hydroxy-nonyloxy)-undec-8(Z)-enoic acid (11,12-ether-EET-8-ZE-OH) and 11,12-trans-oxidoeicosa-8(Z)-enoic acid (11,12-tetra-EET-8-ZE), caused vasorelaxation of mesenteric resistance arteries. Mesenteric myocyte whole-cell (perforated-patch) currents were substantially (∼150%) increased by 11,12-EET and 11,12-EET analogs. Single-channel recordings were conducted to identify the target for 11,12-EET. 11,12-EET and 11,12-EET analogs also increased mesenteric myocyte BKCa channel activity in cell-attached patches. Similar results were obtained in cell-free patches. Baseline mesenteric myocyte BKCa channel activity (NPo) in cell-free patches averaged less than 0.001 at +50 mV and 11,12-EET (1 μmol/L) increased NPo to 0.03 ± 0.02 and 11,12-EET analogs (1 μmol/L) increased NPo to 0.09 ± 0.006. Inhibition of protein phosphatase 2A (PP2A) activity with okadaic acid (10 nmol/L) completely reversed 11,12-EET stimulated BKCa channel activity and greatly attenuated 11,12-ether-EET-8-ZE mesenteric resistance artery vasorelaxation. 11,12-EET and 11,12-EET analogs increased mesenteric myocyte PP2A activity by 3.5-fold. Okadaic acid and the EET inhibitor, 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE) inhibited the 11,12-EET mediated increase in PP2A activity. These findings provide initial evidence that PP2A activity contributes to 11,12-EET and 11,12-EET analog activation of mesenteric resistant artery BKCa channels and vasorelaxation.
AB - Epoxyeicosatrienoic acids (EETs) are considered to be endothelium-derived hyperpolarizing factors, and are potent activators of the large-conductance, Ca2+-activated K+ (BKCa) channel in vascular smooth muscle. Here, we investigate the signal transduction pathway involved in the activation of BKCa channels by 11,12-EET and 11,12-EET stable analogs in rat mesenteric vascular smooth muscle cells. 11,12-EET and the 11,12-EET analogs, 11-nonyloxy-undec-8(Z)-enoic acid (11,12-ether-EET-8-ZE), 11-(9-hydroxy-nonyloxy)-undec-8(Z)-enoic acid (11,12-ether-EET-8-ZE-OH) and 11,12-trans-oxidoeicosa-8(Z)-enoic acid (11,12-tetra-EET-8-ZE), caused vasorelaxation of mesenteric resistance arteries. Mesenteric myocyte whole-cell (perforated-patch) currents were substantially (∼150%) increased by 11,12-EET and 11,12-EET analogs. Single-channel recordings were conducted to identify the target for 11,12-EET. 11,12-EET and 11,12-EET analogs also increased mesenteric myocyte BKCa channel activity in cell-attached patches. Similar results were obtained in cell-free patches. Baseline mesenteric myocyte BKCa channel activity (NPo) in cell-free patches averaged less than 0.001 at +50 mV and 11,12-EET (1 μmol/L) increased NPo to 0.03 ± 0.02 and 11,12-EET analogs (1 μmol/L) increased NPo to 0.09 ± 0.006. Inhibition of protein phosphatase 2A (PP2A) activity with okadaic acid (10 nmol/L) completely reversed 11,12-EET stimulated BKCa channel activity and greatly attenuated 11,12-ether-EET-8-ZE mesenteric resistance artery vasorelaxation. 11,12-EET and 11,12-EET analogs increased mesenteric myocyte PP2A activity by 3.5-fold. Okadaic acid and the EET inhibitor, 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE) inhibited the 11,12-EET mediated increase in PP2A activity. These findings provide initial evidence that PP2A activity contributes to 11,12-EET and 11,12-EET analog activation of mesenteric resistant artery BKCa channels and vasorelaxation.
KW - Calcium-dependent K channels
KW - Eicosanoids
KW - Endothelium-derived hyperpolarizing factor
KW - Mesenteric
KW - Vascular smooth muscle
UR - http://www.scopus.com/inward/record.url?scp=33846414370&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33846414370&partnerID=8YFLogxK
U2 - 10.1016/j.prostaglandins.2006.09.008
DO - 10.1016/j.prostaglandins.2006.09.008
M3 - Article
C2 - 17259072
AN - SCOPUS:33846414370
SN - 1098-8823
VL - 83
SP - 50
EP - 61
JO - Journal of Lipid Mediators and Cell Signalling
JF - Journal of Lipid Mediators and Cell Signalling
IS - 1-2
ER -