Endocardial damage induced by lactate, lowered pH and lactic acid in non-ischemic beating hearts

Elevated levels of urine isocitrate, hydroxymethylglutarate, and formiminoglutamate are associated with arterial stiffness in Korean adults

Recent evidence suggests that cellular perturbations play an important role in the pathogenesis of cardiovascular diseases. Therefore, we analyzed the association between the levels of urinary metabolites and arterial stiffness. Our cross-sectional study included 330 Korean men and women. The brachial-ankle pulse wave velocity was measured as a marker of arterial stiffness. Urinary metabolites were evaluated using a high-performance liquid chromatograph-mass spectrometer. The brachial-ankle pulse wave velocity was found to be positively correlated with l-lactate, citrate, isocitrate, succinate, malate, hydroxymethylglutarate, α-ketoisovalerate, α-keto-β-methylvalerate, methylmalonate, and formiminoglutamate among men. Whereas, among women, the brachial-ankle pulse wave velocity was positively correlated with cis-aconitate, isocitrate, hydroxymethylglutarate, and formiminoglutamate. In the multivariable regression models adjusted for conventional cardiovascular risk factors, three metabolite concentrations (urine isocitrate, hydroxymethylglutarate, and formiminoglutamate) were independently and positively associated with brachial-ankle pulse wave velocity. Increased urine isocitrate, hydroxymethylglutarate, and formiminoglutamate concentrations were associated with brachial-ankle pulse wave velocity and independent of conventional cardiovascular risk factors. Our findings suggest that metabolic disturbances in cells may be related to arterial stiffness.

Six cases of sudden cardiac arrest in alcoholic ketoacidosis

We report herein 6 cases of sudden cardiac arrest in alcoholic ketoacidosis (AKA). All cases displayed evidence of prolonged excessive alcohol consumption and elevated beta-hydroxybutyric acid levels and exhibited pulseless electrical activity (PEA) upon collapse. Severe metabolic acidosis was also seen in all cases. Some cases also displayed concomitant respiratory acidosis, hypothermia, hypoxia and/or hemorrhage. No evidence of myocardial infarction, tamponade or right heart strain, which would suggest pulmonary embolism, was found on cardiac ultrasonography. As PEA in AKA is induced by severe metabolic acidosis, aggressive correction of acidosis may represent a useful therapeutic strategy for such patients.

Uptake and release of carnitine by vascular endothelium in culture; effects of protons and oxygen free radicals

The present paper shows that cultured bovine endothelial cells can be labeled with 3H-carnitine by incubation. This process is slow and is uphill, requiring Na+/K+ ATPase activity. After 3 days incubation isotopic equilibrium is reached, when the cells contain about 0.5 mM (total) carnitine at a medium concentration of about 3 microM. The plasmamembrane barrier is rather resistant to acidosis and oxygen free radicals (OFR). The rate of carnitine release increases significantly only at pH below 5.8. At pH 6.0 the release of stored carnitine can be initiated by the addition of D- or L-lactate. OFR, generated by the addition of xanthine and xanthine oxidase, did not affect carnitine release. Both mild acidosis and OFR left plasmamembranes of endothelial cells intact as judged by the absence of lactate dehydrogenase loss from the cells. Therefore, the known increase of capillary permeability during ischemia and reperfusion may not be due to plasmalemmal disruption of individual endothelial cells, but to increase of inter-endothelial spaces.

The augmentation of leucocyte adhesion to endothelium by therapeutic ultrasound

To determine the effects of exposure of endothelial cells to therapeutic ultrasound on leucocyte adhesion to these cells, confluent cultures of bovine aortic endothelial cells in tissue culture flasks and on collagen coated coverslips were exposed to a maximum of 1.6 W/cm2 1 MHz continuous ultrasound for 15 min, then incubated with neutrophil-rich suspensions containing a known number of viable human leucocytes for intervals from 1 to 240 min. After incubation, nonadherent cells were decanted, the number of leucocytes in the eluted suspension determined and the percentage of adhered cells calculated. Endothelial cell viability was not significantly reduced by ultrasound or by incubation with leucocytes. Whereas untreated endothelial cells were flattened and had surface microvilli, those exposed to ultrasound were plump, rounded and more widely separated along their borders. The percentage of leucocytes that adhered to sonicated endothelium was significantly higher, and this proportion increased with the duration of incubation. Thus, exposure of endothelial cells to ultrasound in vitro can cause intercellular separation and increase the adhesion to leucocytes. If such changes were also to occur in vivo, therapeutic ultrasound would potentiate the inflammatory response.

Interrelationships of ultrastructure and function in the microvasculature of normal and ischaemic myocardium

This paper reviews various methods involving electron microscopy that have been used to investigate the ultrastructure of the vasculature of the normal and diseased heart. Whereas scanning electron microscopy is more commonly employed to record surface topography, it can be used to examine freeze-fracture planes within the myocardium and, using heavy-metal staining and back-scattered electron imaging, to examine large 2-mu-thick resin-embedded sections through the heart. The latter technique allows the comparison of structural alterations across the wall of the heart and thus accurate definition of the transmural progression of pathological processes. Transmission electron microscopy can then be used to provide more detailed information from precisely localised regions. Human myocardium can be usefully studied up to 12 hours post-mortem provided that suitable control material is included. Intravascular tracers including low-viscosity resin and nuclear track emulsion can be used to determine whether or not particular vessels allow flow at the time of fixation, and thus changes in the pattern of flow through the microvasculature due to ischaemia and reperfusion can be quantified and defined. Particular care is required in the fixation of ischaemic tissues because oxygen dissolved in the fixative can lead to the rapid formation of oxygen-free radicals on contact with the tissue. This produces artefactual reoxygenation damage characterised by membrane disruption and cell and organelle swelling, which has previously been attributed to ischaemic injury per se. Bubbling glutaraldehyde with nitrogen substantially reduces this artefact.