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In rat vascular smooth muscle cells (RVSMC), 3-h Na + ,K + -ATPase inhibition by ouabain or in K + -free medium resulted in the inversion of the [Na + ] i /[K + ] i ratio and elevation up to 7-fold the content of Egr1, Atf3, Nr4a1 and Ptgs2 mRNAs. Ouabain increased the rate of 45Ca 2+ influx by 2-fold that was abolished by L-type voltage-gated Ca 2+ channel blocker nicardipine, but it was resistant to Na + /Ca 2+ exchanger inhibitor KB-R7943. To study the role of Ca 2+ -mediated signaling in the expression of Na + i /K + i -sensitive genes we used intracellular Ca 2+ chelator BAPTA and incubated RVSMC in Ca 2+ -free medium. The elevation of Nr4a1 and Ptgs2 expression triggered by ouabain was diminished in Ca 2+ -depeleted cells as well as in the presence of nicardipine and calmodulin antagonists A-7 and W-7. Ptgs2 expression was also suppressed by inhibitor of Ca 2+ /calmodulin-dependent protein kinase (CaMKII) KN-93 whereas increment of Nr4a1 content triggered by ouabain was attenuated by inhibitor of Ca 2+ /calmodulin-dependent protein phosphatase (calcineurin, CaN) cyclosporin A. Neither Ca 2+ depletion nor above listed compounds had any impact on the augmented expression of Egr1 and Atf3 in ouabain-treated RVSMC. Our results strongly suggest that dissipation of transmembrane gradient of monovalent cations increases Ptgs2 and Nr4a1 transcription via augment Ca 2+ influx through L-type Ca 2+ channels that, in turn, leads to CaMKII-mediated phosphorylation of CREB and calcineurin-mediated dephosphorylation of NFAT, respectively. Additional experiments should be performed to identify intermediates of Na + i ,K + i -mediated Ca 2+ -independent excitation-transcription coupling involved the regulation of Egr1 and Atf3 expression. [ABSTRACT FROM AUTHOR]

In rat vascular smooth muscle cells (RVSMC), 3-h Na + ,K + -ATPase inhibition by ouabain or in K + -free medium resulted in the inversion of the [Na + ] i /[K + ] i ratio and elevation up to 7-fold the content of Egr1, Atf3, Nr4a1 and Ptgs2 mRNAs. Ouabain increased the rate of 45Ca 2+ influx by 2-fold that was abolished by L-type voltage-gated Ca 2+ channel blocker nicardipine, but it was resistant to Na + /Ca 2+ exchanger inhibitor KB-R7943. To study the role of Ca 2+ -mediated signaling in the expression of Na + i /K + i -sensitive genes we used intracellular Ca 2+ chelator BAPTA and incubated RVSMC in Ca 2+ -free medium. The elevation of Nr4a1 and Ptgs2 expression triggered by ouabain was diminished in Ca 2+ -depeleted cells as well as in the presence of nicardipine and calmodulin antagonists A-7 and W-7. Ptgs2 expression was also suppressed by inhibitor of Ca 2+ /calmodulin-dependent protein kinase (CaMKII) KN-93 whereas increment of Nr4a1 content triggered by ouabain was attenuated by inhibitor of Ca 2+ /calmodulin-dependent protein phosphatase (calcineurin, CaN) cyclosporin A. Neither Ca 2+ depletion nor above listed compounds had any impact on the augmented expression of Egr1 and Atf3 in ouabain-treated RVSMC. Our results strongly suggest that dissipation of transmembrane gradient of monovalent cations increases Ptgs2 and Nr4a1 transcription via augment Ca 2+ influx through L-type Ca 2+ channels that, in turn, leads to CaMKII-mediated phosphorylation of CREB and calcineurin-mediated dephosphorylation of NFAT, respectively. Additional experiments should be performed to identify intermediates of Na + i ,K + i -mediated Ca 2+ -independent excitation-transcription coupling involved the regulation of Egr1 and Atf3 expression., (Copyright © 2017 Elsevier Ltd. All rights reserved.)