title: Stressor states and the cation crossroads.
abstract: Neurohormonal activation involving the hypothalamic-pituitary-adrenal axis and adrenergic nervous and renin-angiotensin-aldosterone systems is integral to stressor state-mediated homeostatic responses. The levels of effector hormones, depending upon the degree of stress, orchestrate the concordant appearance of hypokalemia, ionized hypocalcemia and hypomagnesemia, hypozincemia, and hyposelenemia. Seemingly contradictory to homeostatic responses wherein the constancy of extracellular fluid would be preserved, upregulation of cognate-binding proteins promotes coordinated translocation of cations to injured tissues, where they participate in wound healing. Associated catecholamine-mediated intracellular cation shifts regulate the equilibrium between pro-oxidants and antioxidant defenses, a critical determinant of cell survival. These acute and chronic stressor-induced iterations in extracellular and intracellular cations are collectively referred to as the cation crossroads. Intracellular cation shifts, particularly excessive accumulation of Ca2+, converge on mitochondria to induce oxidative stress and raise the opening potential of their inner membrane permeability transition pores (mPTPs). The ensuing loss of cationic homeostasis and adenosine triphosphate (ATP) production, together with osmotic swelling, leads to organellar degeneration and cellular necrosis. The overall impact of iterations in extracellular and intracellular cations and their influence on cardiac redox state, cardiomyocyte survival, and myocardial structure and function are addressed herein.
authors.affiliation: Division of Cardiovascular Diseases, University of Tennessee Health Science Center, 956 Court Ave., Suite A312, Memphis, TN 38163, USA. KTWeber@uthsc.edu
authors.forename: Karl T
authors.initials: KT
authors.lastname: Weber
authors.forename: Syamal K
authors.initials: SK
authors.lastname: Bhattacharya
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Newman
authors.forename: Judith E
authors.initials: JE
authors.lastname: Soberman
authors.forename: Kodangudi B
authors.initials: KB
authors.lastname: Ramanathan
authors.forename: Jesse E
authors.initials: JE
authors.lastname: McGee
authors.forename: Kafait U
authors.initials: KU
authors.lastname: Malik
authors.forename: William L
authors.initials: WL
authors.lastname: Hickerson
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism; D002395:Catecholamines / Q000378:metabolism; D002412:Cations / Q000378:metabolism*; D006706:Homeostasis; D006801:Humans; D006996:Hypocalcemia / Q000097:blood / Q000378:metabolism; D007008:Hypokalemia / Q000097:blood / Q000378:metabolism; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000378:metabolism*; D008275:Magnesium Deficiency / Q000097:blood; D008928:Mitochondria / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism; D009336:Necrosis / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism; D018384:Oxidative Stress; D010281:Parathyroid Hormone / Q000378:metabolism; D010913:Pituitary-Adrenal System / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000502:physiology; D012643:Selenium / Q000097:blood / Q000172:deficiency; D013312:Stress, Physiological; D015854:Up-Regulation; D015032:Zinc / Q000097:blood / Q000172:deficiency
chemical_list: D000975:Antioxidants; D002395:Catecholamines; D002412:Cations; D018377:Neurotransmitter Agents; D010281:Parathyroid Hormone; D017382:Reactive Oxygen Species; D000251:Adenosine Triphosphatases; D012643:Selenium; D015032:Zinc