Home
Resources
Publications
Quantitative Energy-Dispersive X-ray Microanalysis of Calcium Dynamics in Cell Suspensions During Stimulation on a Subsecond Time Scale: Preparative and Analytical Aspects as Exemplified With Paramecium Cells

Quantitative Energy-Dispersive X-ray Microanalysis of Calcium Dynamics in Cell Suspensions During Stimulation on a Subsecond Time Scale: Preparative and Analytical Aspects as Exemplified With Paramecium Cells

M Hardt, H Plattner

J Struct Biol. 1999 Dec 15;128(2):187-99.

PMID: 10600572

Abstract:

We analyzed preparative and analytical aspects of the dynamic localization of Ca(2+) during cell stimulation, using a combination of quenched flow and energy-dispersive X-ray microanalysis (EDX). Calcium (or Sr, as a substitute) was retained as fluorides during freeze-substitution, followed by epoxide embedding. The quenched-flow used allowed analyses, during stimulation, in the subsecond time range. Sections of 500 nm were analyzed and no artificial Ca or Sr leakage was recognizable. We calculated a primary beam spread from 63 to 72 nm that roughly indicated the resolution of EDX/structure correlation. These values are quite compatible with the size of potential structures of interest, e.g., Ca stores (approximately 100-nm thickness) or cilia (approximately 250-nm diameter). We used widely different standards to calibrate the ratio of CaK(alpha) net counts in relation to actual ¿Ca. Calibration curves showed a linear relationship and a detection limit of ¿Ca = 2 mM, while ¿Ca in cytosol was 3 mM and in stores was 43 mM, both in nonactivated cells. Eventually Sr(2+) can rapidly be substituted for Ca(2+) in the medium before and during stimulation, thus allowing one to determine Me(2+) fluxes. With our "model" cell, Paramecium, we showed that, upon stimulation (causing rapid Ca(2+) mobilization from subplasmalemmal stores), Ca was immediately exchanged for Sr in stores.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP9004540-G	Dextran 250 Calibration		9004-54-0	Price

As a specialist in analytical chemical Products, Alfa Chemistry offers consumers a wealth of raw materials and a full range of technologies and services.

QUICK LINKS

HEADQUARTERS

Tel:

Fax:

Email: