Inhibition of inwardly rectifying K(+) channels by cGMP in pulmonary vascular endothelial cells.
Endothelial barrier dysfunction is typically triggered by increased intracellular Ca(2+) concentration. Membrane-permeable analogs of guanosine 3',5'-cyclic monophosphate (cGMP) prevent disruption of endothelial cell integrity. Because membrane potential (E(m)), which influences the electrochemical gradient for Ca(2+) influx, is regulated by K(+) channels, we investigated the effect of 8-bromo-cGMP on E(m) and inwardly rectifying K(+) (K(IR)) currents in bovine pulmonary artery and microvascular endothelial cells (BPAEC and BMVEC), using whole cell patch-clamp techniques. Both cell types exhibited inward currents at potentials negative to -50 mV that were abolished by application of 10 microM Ba(2+), consistent with K(IR) current. Ba(2+) also depolarized both cell types. 8-Bromo-cGMP (10(-3) M) depolarized BPAEC and BMVEC and inhibited K(IR) current. Pretreatment with Rp-8-cPCT-cGMPS or KT-5823, protein kinase G (PKG) antagonists, did not prevent current inhibition by 8-bromo-cGMP. These data suggest that 8-bromo-cGMP induces depolarization in BPAEC and BMVEC due, in part, to PKG-independent inhibition of K(IR) current. The depolarization could be a protective mechanism that prevents endothelial cell barrier dysfunction by reducing the driving force for Ca(2+) entry.
Shimoda
Larissa A
LA
Department of Medicine, Division of Pulmonary and Critical Care Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland 21224, USA. shimodal@welch.jhu.edu
Welsh
Laura E
LE
Pearse
David B
DB
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D024661:Potassium Channels, Inwardly Rectifying / Q000037:antagonists & inhibitors*; D011652:Pulmonary Circulation
D024661:Potassium Channels, Inwardly Rectifying; C016276:8-bromocyclic GMP; D017869:Cyclic GMP-Dependent Protein Kinases; D006152:Cyclic GMP