Direct toxic effects of aqueous extract of cigarette smoke on cardiac myocytes at clinically relevant concentrations.
OBJECTIVE
Our goal was to determine if clinically relevant concentrations of aqueous extract of cigarette smoke (CSE) have direct deleterious effects on ventricular myocytes during simulated ischemia, and to investigate the mechanisms involved.


METHODS
CSE was prepared with a smoking chamber. Ischemia was simulated by metabolic inhibition (MI) with cyanide (CN) and 0 glucose. Adult rabbit and mouse ventricular myocyte [Ca(2+)](i) was measured by flow cytometry using fluo-3. Mitochondrial [Ca(2+)] was measured with confocal microscopy, and Rhod-2 fluorescence. The mitochondrial permeability transition (MPT) was detected by TMRM fluorescence and myocyte contracture. Myocyte oxidative stress was quantified by dichlorofluorescein (DCF) fluorescence with confocal microscopy.


RESULTS
CSE 0.1% increased myocyte contracture caused by MI. The nicotine concentration (HPLC) in 0.1% CSE was 15 ng/ml, similar to that in humans after smoking cigarettes. CSE 0.1% increased mitochondrial Ca(2+) uptake, and increased the susceptibility of mitochondria to the MPT. CSE 0.1% increased DCF fluorescence in isolated myocytes, and increased [Ca(2+)](i) in paced myocytes exposed to 2.0 mM CN, 0 glucose (P-MI). These effects were inhibited by the superoxide scavenger Tiron. The effect of CSE on [Ca(2+)](i) during P-MI was also prevented by ranolazine.


CONCLUSIONS
CSE in clinically relevant concentrations increases myocyte [Ca(2+)](i) during simulated ischemia, and increases myocyte susceptibility to the MPT. These effects appear to be mediated at least in part by oxidative radicals in CSE, and likely contribute to the effects of cigarette smoke to increase myocardial infarct size, and to decrease angina threshold.
Cardiology Division, University of Utah, Health Sciences Center, 50 N Medical Dr, Salt Lake City, UT 84132, USA.
Shigeyuki
S
Yamada
Xiu Quan
XQ
Zhang
Toshie
T
Kadono
Nobuhiro
N
Matsuoka
Douglas
D
Rollins
Troy
T
Badger
Christopher K
CK
Rodesch
William H
WH
Barry
D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt / Q000494:pharmacology; D000083:Acetanilides / Q000494:pharmacology; D000787:Angina Pectoris / Q000209:etiology / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006352:Heart Ventricles / Q000187:drug effects; D051379:Mice; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000187:drug effects / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D009200:Myocardial Contraction / Q000187:drug effects*; D009203:Myocardial Infarction / Q000209:etiology / Q000503:physiopathology; D017202:Myocardial Ischemia / Q000150:complications* / Q000378:metabolism / Q000503:physiopathology; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D009538:Nicotine / Q000032:analysis; D010879:Piperazines / Q000494:pharmacology; D011817:Rabbits; D000069458:Ranolazine; D017382:Reactive Oxygen Species / Q000378:metabolism; D012906:Smoke / Q000009:adverse effects* / Q000032:analysis; D012907:Smoking / Q000009:adverse effects*; D013997:Time Factors
D000083:Acetanilides; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D010879:Piperazines; D017382:Reactive Oxygen Species; D012906:Smoke; D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt; D009538:Nicotine; D000069458:Ranolazine; D005947:Glucose; D002118:Calcium