Anesthetics and cardioprotection

The prevalence of the cardiovascular disease significantly affects the outcome of both cardiac and non-cardiac surgery, and perioperative cardiac morbidity is one of the leading causes of death following anesthesia and surgery. The considerable incidence of myocardial infarction, congestive heart failure, myocardial ischemia, or serious dysrhythmias during the intraoperative or postoperative periods, has led many studies to examine medical factors and interventions for decreasing cardiac risk in patients with cardiovascular disease. An extensive amount of work has focused on whether any one anesthetic agent or technique is particularly beneficial for patients with coronary artery disease. Experimental studies conducted in our laboratory have clearly shown that volatile anesthetics may exert profound cardioprotection against myocardial ischemia and reperfusion injury. This article examines the recent evidence about the importance of mitochondria, reactive oxygen species and the KATP channels in cardioprotective signaling by volatile anesthetics. Moreover, the article addresses current concepts and controversies regarding specific roles of the mitochondrial and the sarcolemmal KATP channels in anesthetic-induced preconditioning

Anesthetics and cardioprotection

The prevalence of the cardiovascular disease significantly affects the outcome of both cardiac and non-cardiac surgery, and perioperative cardiac morbidity is one of the leading causes of death following anesthesia and surgery. The considerable incidence of myocardial infarction, congestive heart failure, myocardial ischemia, or serious dysrhythmias during the intraoperative or postoperative periods, has led many studies to examine medical factors and interventions for decreasing cardiac risk in patients with cardiovascular disease. An extensive amount of work has focused on whether any one anesthetic agent or technique is particularly beneficial for patients with coronary artery disease. Experimental studies conducted in our laboratory have clearly shown that volatile anesthetics may exert profound cardioprotection against myocardial ischemia and reperfusion injury. This article examines the recent evidence about the importance of mitochondria, reactive oxygen species and the KATP channels in cardioprotective signaling by volatile anesthetics. Moreover, the article addresses current concepts and controversies regarding specific roles of the mitochondrial and the sarcolemmal KATP channels in anesthetic-induced preconditioning

Isoflurane Modulates Cardiac Mitochondrial Bioenergetics by Selectively Attenuating Respiratory Complexes

Mitochondrial dysfunction contributes to cardiac ischemia–reperfusion (IR) injury but volatile anesthetics (VA) may alter mitochondrial function to trigger cardioprotection. We hypothesized that the VA isoflurane (ISO) mediates cardioprotection in part by altering the function of several respiratory and transport proteins involved in oxidative phosphorylation (OxPhos). To test this we used fluorescence spectrophotometry to measure the effects of ISO (0, 0.5, 1, 2 mM) on the time-course of interlinked mitochondrial bioenergetic variables during states 2, 3 and 4 respiration in the presence of either complex I substrate K+-pyruvate/malate (PM) or complex II substrate K+-succinate (SUC) at physiological levels of extra-matrix free Ca2 + (~ 200 nM) and Na+ (10 mM). To mimic ISO effects on mitochondrial functions and to clearly delineate the possible ISO targets, the observed actions of ISO were interpreted by comparing effects of ISO to those elicited by low concentrations of inhibitors that act at each respiratory complex, e.g. rotenone (ROT) at complex I or antimycin A (AA) at complex III. Our conclusions are based primarily on the similar responses of ISO and titrated concentrations of ETC. inhibitors during state 3. We found that with the substrate PM, ISO and ROT similarly decreased the magnitude of state 3 NADH oxidation and increased the duration of state 3 NADH oxidation, ΔΨm depolarization, and respiration in a concentration-dependent manner, whereas with substrate SUC, ISO and ROT decreased the duration of state 3 NADH oxidation, ΔΨm depolarization and respiration. Unlike AA, ISO reduced the magnitude of state 3 NADH oxidation with PM or SUC as substrate. With substrate SUC, after complete block of complex I with ROT, ISO and AA similarly increased the duration of state 3 ΔΨm depolarization and respiration. This study provides a mechanistic understanding in how ISO alters mitochondrial function in a way that may lead to cardioprotection

Enhanced charge-independent Mitochondrial Free Ca\u3csup\u3e2+\u3c/sup\u3e and Attenuated ADP-induced NADH Oxidation by Isoflurane: Implications for Cardioprotection

Modulation of mitochondrial free Ca2 + ([Ca2 +]m) is implicated as one of the possible upstream factors that initiates anesthetic-mediated cardioprotection against ischemia–reperfusion (IR) injury. To unravel possible mechanisms by which volatile anesthetics modulate [Ca2 +]m and mitochondrial bioenergetics, with implications for cardioprotection, experiments were conducted to spectrofluorometrically measure concentration-dependent effects of isoflurane (0.5, 1, 1.5, 2 mM) on the magnitudes and time-courses of [Ca2 +]m and mitochondrial redox state (NADH), membrane potential (ΔΨm), respiration, and matrix volume. Isolated mitochondria from rat hearts were energized with 10 mM Na+- or K+-pyruvate/malate (NaPM or KPM) or Na+-succinate (NaSuc) followed by additions of isoflurane, 0.5 mM CaCl2 (≈ 200 nM free Ca2 + with 1 mM EGTA buffer), and 250 μM ADP. Isoflurane stepwise: (a) increased [Ca2 +]m in state 2 with NaPM, but not with KPM substrate, despite an isoflurane-induced slight fall in ΔΨm and a mild matrix expansion, and (b) decreased NADH oxidation, respiration, ΔΨm, and matrix volume in state 3, while prolonging the duration of state 3 NADH oxidation, respiration, ΔΨm, and matrix contraction with PM substrates. These findings suggest that isoflurane\u27s effects are mediated in part at the mitochondrial level: (1) to enhance the net rate of state 2 Ca2 + uptake by inhibiting the Na+/Ca2 + exchanger (NCE), independent of changes in ΔΨm and matrix volume, and (2) to decrease the rates of state 3 electron transfer and ADP phosphorylation by inhibiting complex I. These direct effects of isoflurane to increase [Ca2 +]m, while depressing NCE activity and oxidative phosphorylation, could underlie the mechanisms by which isoflurane provides cardioprotection against IR injury at the mitochondrial level

Ketamine Induces Neuroapoptosis in Stem Cell–Derived Developing Human Neurons Possibly through Intracellular Calcium/Mitochondria/microRNA Signaling Pathway

Ketamine, one of the commonly used agents in pediatric anesthesia, has been linked to neurodegeneration and cognitive dysfunction in developing animal models. Previous studies on developing neurons derived from human embryonic stem cells (hESCs) indicate that ketamine induces neuroapoptosis and the mechanisms remain largely unknown. This study aims to investigate the effect of ketamine on intracellular calcium, mitochondrial signaling, and microRNA profiles in hESCs-derived 2-week-old neurons. The neurons were exposed to ketamine for 6 or 24 hours. Neuroapoptosis was assessed by TUNEL staining. Intracellular calcium level was analyzed using Fluo-4 AM staining. The mitochondria-related neuroapoptosis pathway including mitochondrial membrane potential, cytochrome c release from mitochondria to cytosol, and mitochondrial fission was also investigated. miScript miRNA arrays were used in microRNA target identification studies. The results showed that ketamine exposure induced neuroapoptosis and alterations in intracellular calcium levels. In addition, ketamine decreased mitochondrial membrane potential, resulted in cytochrome c release from mitochondria into cytosol, and increased mitochondrial fission. Among 88 microRNAs investigated, let-7a/e, miR-21, miR-23b, miR-28-5p, and miR-423-5p were found downregulated, while miR-96 was upregulated in the neurons treated with ketamine. Collectively, our findings indicate that ketamine induces neuroapoptosis possibly through the dysregulated intracellular calcium, mitochondria, and microRNA pathway

Generation of human induced pluripotent stem cells by simple transient transfection of plasmid DNA encoding reprogramming factors

<p>Abstract</p> <p>Background</p> <p>The use of lentiviruses to reprogram human somatic cells into induced pluripotent stem (iPS) cells could limit their therapeutic usefulness due to the integration of viral DNA sequences into the genome of the recipient cell. Recent work has demonstrated that human iPS cells can be generated using episomal plasmids, excisable transposons, adeno or sendai viruses, mRNA, or recombinant proteins. While these approaches offer an advance, the protocols have some drawbacks. Commonly the procedures require either subcloning to identify human iPS cells that are free of exogenous DNA, a knowledge of virology and safe handling procedures, or a detailed understanding of protein biochemistry.</p> <p>Results</p> <p>Here we report a simple approach that facilitates the reprogramming of human somatic cells using standard techniques to transfect expression plasmids that encode OCT4, NANOG, SOX2, and LIN28 without the need for episomal stability or selection. The resulting human iPS cells are free of DNA integration, express pluripotent markers, and form teratomas in immunodeficient animals. These iPS cells were also able to undergo directed differentiation into hepatocyte-like and cardiac myocyte-like cells in culture.</p> <p>Conclusions</p> <p>Simple transient transfection of plasmid DNA encoding reprogramming factors is sufficient to generate human iPS cells from primary fibroblasts that are free of exogenous DNA integrations. This approach is highly accessible and could expand the use of iPS cells in the study of human disease and development.</p

Clinical Relevance of lncRNA and Mitochondrial Targeted Antioxidants as Therapeutic Options in Regulating Oxidative Stress and Mitochondrial Function in Vascular Complications of Diabetes

Metabolic imbalances and persistent hyperglycemia are widely recognized as driving forces for augmented cytosolic and mitochondrial reactive oxygen species (ROS) in diabetes mellitus (DM), fostering the development of vascular complications such as diabetic nephropathy, diabetic cardiomyopathy, diabetic neuropathy, and diabetic retinopathy. Therefore, specific therapeutic approaches capable of modulating oxidative milieu may provide a preventative and/or therapeutic benefit against the development of cardiovascular complications in diabetes patients. Recent studies have demonstrated epigenetic alterations in circulating and tissue-specific long non-coding RNA (lncRNA) signatures in vascular complications of DM regulating mitochondrial function under oxidative stress. Intriguingly, over the past decade mitochondria-targeted antioxidants (MTAs) have emerged as a promising therapeutic option for managing oxidative stress-induced diseases. Here, we review the present status of lncRNA as a diagnostic biomarker and potential regulator of oxidative stress in vascular complications of DM. We also discuss the recent advances in using MTAs in different animal models and clinical trials. We summarize the prospects and challenges for the use of MTAs in treating vascular diseases and their application in translation medicine, which may be beneficial in MTA drug design development, and their application in translational medicine