Cardiotonic steroids: potential endogenous sodium pump ligands with diverse function.
The highly conserved cardiotonic steroid (CS) binding site present on the ubiquitous membrane sodium pump, sodium, potassium-ATPase, appears to have been conserved by no force other than its capacity to bind CS: a family that includes plant-derived cardiac glycosides and putative endogenous vertebrate counterparts. Binding of ligand is inhibited by increased extracellular potassium. This implies functional coordination because inhibition of the sodium pump would be counterproductive when extracellular potassium is elevated. The interesting biology of the CS binding site continues to stimulate investigations into the identity of endogenous ligands, their role as pump regulators at the cellular level, and as mediators of body fluid balance and blood pressure regulation. In addition to inhibition of sodium and potassium transport, there is considerable recent evidence suggesting that the sodium pump may act as a cell signaling receptor activated by CS binding and responding by coordination of intracellular signaling pathways that can be dependent on and also independent of the reduction in transmembrane ion flux resulting directly from pump inhibition. This signaling may influence cell survival, growth, and differentiation. Recent insight into the biology of pump regulation by CS is reviewed.
Institute of Molecular Medicine, University of Texas, Houston, Texas 77030, USA.
Renata I
RI
Dmitrieva
Peter A
PA
Doris
D000302:Adrenal Cortex / Q000378:metabolism; D000306:Adrenal Cortex Neoplasms / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002018:Bufanolides / Q000494:pharmacology; D002025:Bufonidae / Q000378:metabolism; D002301:Cardiac Glycosides / Q000494:pharmacology* / Q000627:therapeutic use; D002316:Cardiotonic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002417:Cattle; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D017136:Ion Transport / Q000187:drug effects; D008322:Mammals / Q000378:metabolism; D051379:Mice; D009318:Natriuresis / Q000187:drug effects / Q000502:physiology; D009369:Neoplasms / Q000188:drug therapy; D011188:Potassium / Q000494:pharmacology; D011225:Pre-Eclampsia / Q000378:metabolism; D011247:Pregnancy; D015398:Signal Transduction / Q000187:drug effects; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000187:drug effects*
D000970:Antineoplastic Agents; D002018:Bufanolides; D002301:Cardiac Glycosides; D002316:Cardiotonic Agents; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium