Also see:
PUFA Decrease Cellular Energy Production
PUFA Breakdown Products Depress Mitochondrial Respiration
The Randle Cycle
PUFA, Ketones, and Sugar Restriction Promote Tumor Growth
“Free fatty acids suppress mitochondrial respiration (Kamikawa and Yamazaki, 1981), leading to increased glycolysis (producing lactic acid) to maintain cellular energy. The suppression of mitochondrial respiration increase the production of toxic free radicals, and the decreased carbon dioxide makes the proteins more susceptible to attack by free radicals.” -Ray Peat, PhD
Jpn Heart J. 1981 Nov;22(6):939-49.
Effect of high plasma free fatty acids on the free radical formation of myocardial mitochondria isolated from ischemic dog hearts.
Kamikawa T, Yamazaki N.
Effects of high plasma free fatty acids (FFA) on the free radical formation of myocardial mitochondria, isolated from normal and ischemic dog hearts, were studied by electron spin resonance (ESR) spectrometry. Free radical concentrations in state 4 respiration were used for the evaluation of the function in the mitochondria in this study. High plasma FFA levels were induced either by intravenous injection of Intralipid and heparin, or by infusion of norepinephrine. Ischemic hearts were induced by inserting a Cournand’s 7F catheter into the left coronary artery under fluoroscopic control. Exogenous high plasma FFA induced by Intralipid and heparin caused the decrease of free radicals in state 4 respiration in the mitochondria isolated from normal and ischemic dog hearts. Endogenous high FFA induced by continuous infusion of norepinephrine also caused the decrease of free radicals. On the other hand, nicotinic acid prevented the decrease of free radicals as well as the rise of plasma FFA by the norepinephrine infusion. These results suggest that high plasma FFA itself, whether it may be exogenous or endogenous, may impair the oxidative phosphorylation of the mitochondria isolated from normal and ischemic hearts.
Suppressing fatty acid oxidation improves the contraction of the heart muscle and increases the efficiency of oxygen use (Chandler, et al., 2003). -Ray Peat, PhD
Cardiovasc Res (2003) 59 (1): 143-151.
Partial inhibition of fatty acid oxidation increases regional contractile power and efficiency during demand-induced ischemia
Margaret P. Chandlera, (mpc10@po.cwru.edu), Pedro N. Chavezb, Tracy A. McElfresha, Hazel Huanga, Charles S. Harmonc and William C. Stanleya
Objective: Clinical trials in patients with stable angina show that drugs that partially inhibit myocardial fatty acid oxidation reduce the symptoms of demand-induced ischemia, presumably by reducing lactate production and improving regional systolic function. We tested the hypothesis that partial inhibition of fatty acid oxidation with oxfenicine (a carnitine palmitoyl transferase-I inhibitor) reduces lactate production and increases regional myocardial power during demand-induced ischemia. Methods: Demand-induced ischemia was produced in anesthetized open-chest swine by reducing flow by 20% in the left anterior descending coronary artery and increasing heart rate and contractility with dobutamine (15 μg kg−1 min−1 i.v.) for 20 min. Glucose and fatty acid oxidation were measured with an intracoronary infusion of [U-14C] glucose and [9,10-3H] oleate, and hearts were treated with oxfenicine (2 mmol l−1; n = 7) or vehicle (n = 7). Regional anterior wall power was assessed from the left ventricular pressure–anterior free wall segment length loops. Results: During demand-induced ischemia, the oxfenicine group had a higher rate of glucose oxidation (6.9±1.1 vs. 4. 7±0.8 μmol min−1; P<0.05), significantly lower fatty acid uptake, but no change in total or active PDH activity. The oxfenicine group had significantly lower lactate output integrals (1.11±0.23 vs. 0.60±0.11 mmol) and glycogen depletion (66±6 vs. 43±8%), and higher anterior wall power index (0.95±0.17 vs. 1.30±0.11%) and anterior wall energy efficiency index (91±17 vs. 129±10%). Conclusions: Partial inhibition of fatty acid oxidation reduced non-oxidative glycolysis and improved regional contractile power and efficiency during demand-induced ischemia.
When stress is very intense, as in trauma or sepsis, the reaction of liberating fatty acids can become dangerously counter-productive, producing the state of shock. In shock, the liberation of free fatty acids interferes with the use of glucose for energy and causes cells to take up water and calcium (depleting blood volume and reducing circulation) and to leak ATP, enzymes, and other cell contents (Boudreault and Grygorczyk, 2008; Wolfe, et al., 1983; Selzner, et al., 2004; van der Wijk, 2003), in something like a systemic inflammatory state (Fabiano, et al., 2008) often leading to death. -Ray Peat, PhD
J Physiol. 2004 Dec 1;561(Pt 2):499-513. Epub 2004 Oct 7.
Cell swelling-induced ATP release is tightly dependent on intracellular calcium elevations.
Boudreault F, Grygorczyk R.
Mechanical stresses release ATP from a variety of cells by a poorly defined mechanism(s). Using custom-designed flow-through chambers, we investigated the kinetics of cell swelling-induced ATP secretion, cell volume and intracellular calcium changes in epithelial A549 and 16HBE14o- cells, and NIH/3T3 fibroblasts. Fifty per cent hypotonic shock triggered transient ATP release from cell confluent monolayers, which consistently peaked at around 1 min 45 s for A549 and NIH/3T3, and at 3 min for 16HBE14o- cells, then declined to baseline within the next 15 min. Whereas the release time course had a similar pattern for the three cell types, the peak rates differed significantly (294 +/- 67, 70 +/- 22 and 17 +/- 2.8 pmol min(-1) (10(6) cells)(-1), for A549, 16HBE14o- and NIH/3T3, respectively). The concomitant volume changes of substrate-attached cells were analysed by a 3-dimensional cell shape reconstruction method based on images acquired from two perpendicular directions. The three cell types swelled at a similar rate, reaching maximal expansion in 1 min 45 s, but differed in the duration of the volume plateau and regulatory volume decrease (RVD). These experiments revealed that ATP release does not correlate with either cell volume expansion and the expected activation of stretch-sensitive channels, or with the activation of volume-sensitive, 5-nitro-2-(3-phenylpropylamino) benzoic acid-inhibitable anion channels during RVD. By contrast, ATP release was tightly synchronized, in all three cell types, with cytosolic calcium elevations. Furthermore, loading A549 cells with the calcium chelator BAPTA significantly diminished ATP release (71% inhibition of the peak rate), while the calcium ionophore ionomycin triggered ATP release in the absence of cell swelling. Lowering the temperature to 10 degrees C almost completely abolished A549 cell swelling-induced ATP release (95% inhibition of the peak rate). These results strongly suggest that calcium-dependent exocytosis plays a major role in mechanosensitive ATP release.
Prog Clin Biol Res. 1983;111:89-109.
Energy metabolism in trauma and sepsis: the role of fat.
Wolfe RR, Shaw JH, Durkot MJ.
There seems little doubt that there are signals for the increased mobilization of fat in shock, trauma, and sepsis. Whether those signals are reflected by an actual increase in mobilization is dependent on many variables including cardiovascular status. A hypothetical scheme based on our own experiments in the hyperdynamics phases of response to burn injury and to sepsis is presented in Figure 8. According to this scheme, catecholamines stimulate lipolysis in the adipose tissue, resulting in the release of glycerol and FFA into the plasma at increased rates. The glycerol is cleared by the liver and converted into glucose–a process stimulated by, among other things, glucagon. Some of the increased flux of FFA is also cleared by the liver, whereupon the fatty acids are incorporated into VLDL and released again into the plasma. The increased FFA levels also exert a dampening effect on the factors stimulating hepatic glucose production. At the periphery, plasma FFA as well as VLDL fatty acids are taken up at an increased rate. The tissues are attuned to the oxidation of fat, and as a consequence most of the energy production is derived from fat oxidation. The increased fatty acids exert an inhibitory effect on the complete oxidation of glucose, so although glucose may be taken up at an accelerated rate, the relative contribution of glucose oxidation to total energy production may fall. Rather than being completely oxidized, pyruvate is reduced to lactate and released into the plasma at an accelerated rate. The lactate then contributes to the production of glucose in the liver, completing a cyclical process called the Cori Cycle. Although all aspects of this scheme are supported by data highlighted in this paper, it certainly must be an oversimplification of the overall response of substrate metabolism to trauma and sepsis. It is presented for the purpose of highlighting the potential role of fat as a controller of the metabolic response, and to suggest that the enhanced mobilization and oxidation of fat is one of the fundamental responses to stress.
Cell Death Differ. 2004 Dec;11 Suppl 2:S172-80.
Water induces autocrine stimulation of tumor cell killing through ATP release and P2 receptor binding.
Selzner N, Selzner M, Graf R, Ungethuem U, Fitz JG, Clavien PA.
Although exposure of cells to extreme hypotonic stress appears to be a purely experimental set up, it has found an application in clinical routine. For years, surgeons have washed the abdominal cavity with distilled water to lyse isolated cancer cells left after surgery. No data are available supporting this practice or evaluating the potential mechanisms of cell injury under these circumstances. Recent evidence indicates that increases in cell volume stimulate release of adenosine triphosphate and autocrine stimulation of purinergic (P2) receptors in the plasma membrane of certain epithelial cell types. Under physiological conditions, purigenic stimulation can contribute to cell volume recovery through activation of solute efflux. In addition, adenosine triphosphate-P2 receptor binding might trigger other mechanisms affecting cell viability after profound hypotonic stress. This study demonstrates a novel pathway of cell death by apoptosis in human colon cancer cells following a short hypotonic stress. This pathway is induced by transitory cell swelling which leads to extracellular release of adenosine triphosphate (ATP) and specific binding of ATP to P2 receptors (probably P2X7). Extracellular ATP induced activation of caspases 3 and 8, annexin V, release of cytochrome c, and eventually cell death. The effect of ATP can be blocked by addition of (i) apyrase to hydrolyse extracellular ATP and (ii) suramin, a P2 receptor antagonist. Finally, (iii) gadolinium pretreatment, a blocker of ATP release, reduces sensitivity of the cells to hypotonic stress. The adenosine triphosphate-P2 receptor cell death pathway suggests that autocrine/paracrine signaling may contribute to regulation of viability in certain cancer cells disclosed with this pathway.
J Biol Chem. 2003 Oct 10;278(41):40020-5. Epub 2003 Jul 18.
Increased vesicle recycling in response to osmotic cell swelling. Cause and consequence of hypotonicity-provoked ATP release.
van der Wijk T, Tomassen SF, Houtsmuller AB, de Jonge HR, Tilly BC.
Osmotic swelling of Intestine 407 cells leads to an immediate increase in cell surface membrane area as determined using the fluorescent membrane dye FM 1-43. In addition, as measured by tetramethylrhodamine isothiocyanate (TRITC)-dextran uptake, a robust (>100-fold) increase in the rate of endocytosis was observed, starting after a discrete lag time of 2-3 min and lasting for approximately 10-15 min. The hypotonicity-induced increase in membrane surface area, like the cell swelling-induced release of ATP (Van der Wijk, T., De Jonge, H. R., and Tilly, B. C. (1999) Biochem. J. 343, 579-586), was diminished after 1,2-bis(2-aminophenoxy)ethane-N,N,N’,N’-tetraacetic acid-acetoxymethyl ester loading or cytochalasin B treatment. Uptake of TRITC-dextrans, however, was not affected. Treatment of the cells with the vesicle-soluble N-ethylmaleimide-sensitive factor attachment protein receptor-specific protease Clostridium botulinum toxin F not only nearly eliminated the hypotonicity-induced increase in membrane surface area but also strongly diminished the release of ATP, indicating the involvement of regulated exocytosis. Both the ATP hydrolase apyrase and the MEK inhibitor PD098059 diminished the osmotic swelling-induced increase in membrane surface area as well as the subsequent uptake of TRITC-dextrans. Taken together, the results indicate that extracellular ATP is required for the hypotonicity-induced vesicle recycling and suggest that a positive feedback loop, involving purinergic activation of the Erk-1/2 pathway, may contribute to the release of ATP from hypo-osmotically stimulated cells.
Science 23 January 1976: Vol. 191 no. 4224 pp. 293-295
What retains water in living cells?
GN Ling, CL Walton
Three types of evidence are presented showing that the retention of cell water does not necessarily depend on the possession of an intact cell membrane. The data agree with the concept that water retention in cells is due to multilayer adsorption on proteins and that the maintenance of the normal state of water relies on the presence of adenosine triphosphate as a cardinal adsorbent, controlling the protein conformations.
