X-ray microanalysis of in situ and isolated pancreatic islets.
The effect of stimulation of insulin secretion in pancreatic beta cells on the elemental composition of these cells was investigated by x-ray microanalysis. In vitro experiments on isolated islets of Langerhans from ob/ob mice were compared to in situ experiments. The only significant difference in the elemental composition of beta cells from ob/ob mice versus their lean counterparts is a lower Ca concentration in the ob/ob animals. The nucleus of the beta cells has a higher concentration of P, K, and Na than the cytoplasm, which has a higher concentration of S and Cl. No polarized ion distribution in the cytoplasm of the beta cells was observed. Isolated beta cells show a higher concentration of Na and Cl and a lower concentration of K than their in situ counterparts. Stimulation of insulin secretion with glucose both in situ and in vitro showed only very small effects on the elemental composition of the beta cells: a tendency to a decreased P content was noted. In vitro experiments using stimulation with high extracellular K+ showed, in addition, a small increase in the intracellular K concentration. In conclusion, while the elemental content of beta cells in vitro differs from that in situ, the response to glucose stimulation appears to be similar in both systems.
Wróblewski
R
R
Department of Pathology, Karolinska Institute, Stockholm, Sweden.
Pålsgård
E
E
Juntti-Berggren
L
L
Berggren
P O
PO
Roomans
G M
GM
D000818:Animals; D002118:Calcium / Q000032:analysis; D002712:Chlorides / Q000032:analysis; D003593:Cytoplasm / Q000737:chemistry; D004577:Electron Probe Microanalysis; D005947:Glucose / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008820:Mice, Obese; D010758:Phosphorus / Q000032:analysis; D011188:Potassium / Q000032:analysis; D012964:Sodium / Q000032:analysis; D013455:Sulfur / Q000032:analysis; D015032:Zinc / Q000032:analysis
D002712:Chlorides; D007328:Insulin; D010758:Phosphorus; D013455:Sulfur; D012964:Sodium; D005947:Glucose; D015032:Zinc; D011188:Potassium; D002118:Calcium