Direct measurement of elemental distributions in insulin-producing cells using nuclear microscopy.

The nuclear microprobe was used to study elemental distributions in cultured insulin-producing cells and in pancreatic tissue. To see whether insulin producing cells are polarized, the cells were stimulated in the presence of Sr as a Ca analogue. The cells were stimulated to secrete insulin and Sr was detected in cells after momentary stimulation. We did not detect a polarized distribution of Sr in the RINm5F-cells. The distributions of Ca and Zn were affected when beta-cells (ob/ob) from a primary culture flattened out onto a substrate. In uprounded beta-cells (ob/ob) the distribution of Ca and Zn was polarized. Pancreatic tissue (ob/ob) was prepared for elemental analysis using freeze-substitution in tetrahydrofurane (THF) followed by embedding in Araldite. The resulting samples can be sectioned at room temperature, easing physiological studies.