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Microdialysis as a tool to assess interstitial norepinephrine levels in adipose tissue of spontaneously hypertensive rats.
No full textThe microdialysis technique was applied to the study of norepinephrine (NE) metabolism in white adipose tissue of spontaneously hypertensive (SHR, n = 6) and normotensive Wistar-Kyoto (WKY, n = 6) rats. Mean concentrations of interstitial NE were much higher in SHR as compared to WKY (mean +/- SEM: 980.9 +/- 125.6 pg/ml vs 520.7 +/- 96.1 pg/ml; p = 0.01) over the 180 min experimental period. These results are consistent with the hypothesis that sustained outflow from nerve endings of the peripheral sympathetic system may play a role in the maintenance of arterial hypertension. Owing to its low invasiveness, the microdialysis technique allows to continuously monitor NE extracellular levels in conscious and freely-moving animals
Impact of myocardial geometry on left ventricular performance in healthy black and white young adults
No full textRacial differences in left ventricular (LV) structure are suggested by clinical and experimental studies. This study evaluates if racial differences in LV performance exist comparing black to white young males, by tissue Doppler echocardiography and myocardial performance index (MPI). We examined 40 healthy males, 20 blacks (mean age 27.6 +/- 4.4 years) and 20 whites (mean age 26.5 +/- 6.7 years). All subjects underwent conventional echocardiography, tissue Doppler echocardiography, and MPI assessment. No differences were found in LV diameters, volumes, mass, and hemodynamic measurements. Septal and posterior wall thicknesses were significantly increased in black subjects as well as the relative wall thickness. Systolic and diastolic functions estimated by conventional parameters were superimposable in the two groups. In black subjects, a significant increase of septal S-wave, peak velocity, and time-velocity integral were found. MPI was significantly higher in black compared to white subjects (0.46 +/- 0.05 vs 0.40 +/- 0.06, P < 0.002). A significant correlation between MPI and relative wall thickness (r = 0.54) was demonstrated. Besides, MPI correlated with S(pv) (r = 0.55) and S(tvi) (r = 0.38) at the septal site. In conclusion our data show a higher MPI in black subjects that seems to be geometry-dependent. Correlations between MPI and tissue Doppler echocardiography systolic indexes were found. Our findings suggest that racial differences in LV performance exist, especially, in the systolic function, even in the absence of other conventional echocardiographic changes
Receptor-ligand internalization
No full textAbstract
The interaction between biologically active compounds and target cells has been
studied extensively by various quantitative and qualitative approaches as it is the
crucial first step in the chain of events leading to the final effect. Additionally it is a
suitable process to be studied for pharmacological purposes.
The visualization of receptor–ligand binding and internalization has been studied
by immunocytochemistry techniques for both light and electron microscopy on
fixed, permeabilized tissues or cells. The information achievable by these methods
is limited and static, as the localization observed in fixed samples might not
correspond to the actual binding site in living cells and the time course of the
interaction cannot be evaluated with satisfactory precision.
A technique is now available that allows the visualization of the interaction
between directly fluoresceinated ligands and living cells and enables one to follow
their possible internalization. In living adherent cells, such a methodological
approach was hindered previously by the relatively poor resolution of the conventional fluorescence microscope and the unfavorable signal-to-noise ratio. As aconsequence, the visual information has not been exhaustive and subcellular localization has been limited to main cell compartments.
More recently, confocal imaging has provided new insights in the observation of
fluorescent specimens. The virtual absence of out-of-focus blurring allows a much
better definition of probe localization at the subcellular level together with the
possibility of exploiting the three-dimensional reconstruction capability of most
confocal systems.
We have coupled a self-constructed flow chamber to an inverted confocal scanning
laser microscope that allows long-term observation of adherent cells under
controlled microenvironmental conditions. This method not
only provides images of intact, nonfixed cells, but also allows one to change culture
conditions and to observe living cell responses directly or to perform two-step
staining to identify subcellular structures involved in the observed processes
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