van der Gj Ger Vusse

Co(III)EDTA as extra-cellular marker in μPIXE-analysis of rat cardiomyocytes

In previous studies no clear difference was found between the intra- and extra-cellular compartment in nuclear microprobe elemental distribution maps of freeze-dried cryo sections of heart tissue. Probably due to artefacts during the preparation of these samples, the intra-cellular and the extra-cellular content of elements are mixed up. In this article a method, using NaCo(III)EDTA as an extra-cellular marker, was applied to deconvolute the total ion content in an extra- and intra-cellular contribution. This method was both applied to normoxic heart tissue and low-flow ischemic heart tissue. Intra-cellular ion concentrations calculated from the corrected ion contents of the normoxic tissue agrees well with literature values. Moreover a clear elevation of the intra-cellular sodium and chlorine concentration was found in low-flow ischemic tissue.

Mathematical modelling of the calcium-left ventricular pressure relationship in the intact diabetic rat heart

Aim:  The objective was to characterize cross‐bridge kinetics from the cytoplasmic calcium ion concentration ([Ca2+]i) and the left ventricular pressure (LVP) in the early‐stage diabetic rat heart under baseline conditions and upon β‐adrenergic stimulation.

PIXE microanalysis of trace elements of the normoxic, ischemic and reperfused rat heart

With a 3 x 3 mu m(2) proton microbeam spatial distributions of Na, Mg, P, S, K, Ca and Fe were measured via PIXE in 50 x 50 mu m(2) areas of rat heart, sliced into 10-15 mu m thick cryosections. The isolated rat hearts were subjected to normal perfusion, ischemia and reperfusion. Substantial changes in the elemental distribution were found in tissue after 40 min. of reperfusion, particularly indicated by locally elevated Ca and decreased K levels. Electron microscopic examination was used for assessment of artefacts due to sample preparation and handling. Results of stained cryosections analyzed via STIM demonstrated that this latter technique can be employed prior to PIXE analysis to localize individual cells in freeze-dried cryosections.

State and history of heart tissue preparation for proton microprobe elemental analysis at the Eindhoven Cyclotron Laboratory

Proton microprobe techniques are useful in investigating ischemia-reperfusion induced ion shifts between cardiac muscle cells and interstitial fluid. Preliminary results have shown that proper analysis of ion concentrations in various cardiac compartments is hampered by dislocation of elements during sample preparation. In this study the different stages of the preparation were evaluated as possible sources of artifacts. After improvements of the sample preparation procedure, sharp ion concentration gradients within heart tissue preparations were obtained, indicating no noticeable ion dislocation at the scale of the measurements.

Computational analysis of calcium transients in the intact rat heart; model identification

The sarcoplasmic calcium transients determine the contraction strength during the cardiac cycle. A computational model has been derived that can be uniquely identified based on the available time series data of the free calcium concentration in the sarcoplasm. The model assesses the quantitatively most important processes in calcium handling in the intact heart at an integral system level. The in vivo kinetic parameters of cardiac calcium handling have been analyzed.The sarcoplasmic calcium transients determine the contraction strength during the cardiac cycle. A computational model has been derived that can be uniquely identified based on the available time series data of the free calcium concentration in the sarcoplasm. The model assesses the quantitatively most important processes in calcium handling in the intact heart at an integral system level. The in vivo kinetic parameters of cardiac calcium handling have been analyzed.

Determination of the intracellular element concentrations in cultured H9c2 cells by proton microprobe techniques

The present study was conducted to investigate the applicability of proton microprobe techniques in the assessment of intracellular ion concentrations in individual cardiac-type H9c2 cells. Several methods to minimise the contribution of the extracellular environment were explored. Preliminary results indicate that proton microprobe techniques might be useful to assess intracellular ion concentrations in individual, cultured cells.

NUCLEAR ELEMENTAL ANALYSES WITH A CYCLOTRON ON BIOMEDICAL SAMPLES

The Eindhoven scanning proton microprobe enables the determination of the ion content of heart tissue on a sub-cellular scale. It is shown that intra-cellular elemental concentrations can be determined. Measurements are carried out for physiological and patho-physiological rat heart muscle tissue. Important alterations in Na and K concentrations are reported as measured with PIXE, RBS and NFS techniques employing a variable energy cyclotron (3–30 MeV). However, quantitative intra-cellular determinations are hampered by the presence of extra-cellular space (ECS). For this purpose, cobaltic ethylene-diamine-tetra-acetic-acid (Co(III)EDTA) was used as an exogenic ECS marker. The intra-cellular ion concentrations of normoxic tissue after correction for the ECS agree well with the literature values.