Calcium and magnesium in exocrine secretion--an X-ray microanalytical study

Journal Article · Fri Jan 01 04:00:00 EST 1982 · Scanning Electron Microsc.; (United States)

OSTI ID:5864802

Roomans, G M; Barnard, T

Calcium and magnesium distribution in mammalian exocrine glands under resting, stimulated and pathological conditions was investigated by X-ray microanalysis of thick and ultrathin cryosections. Ultrathin sections were cut from tissue frozen in the presence of a polymer cryoprotectant, dextran. The effect of this treatment on isolated rabbit pancreas. Dextran caused a disturbance in water and ion transport, partly due to an osmotic effect and the impermeability of the pancreatic epithelium to dextran; this does, however, not necessarily invalidate intracellular measurements on frozen-dried sections. Cholinergic stimulation of the rat pancreas caused a change of Ca distribution from the basal to the apical part of the cell; this may be a component of the secretory Ca flux. Kinetic considerations make a significant Ca movement via the ER-Golgi endomembrane space less likely. The mitochondrial Ca concentration is low, and not significantly changed by cholinergic stimulation. X-ray microanalysis was carried out on submandibular glands of rats after chronic treatment with reserpin and/or isoproterenol (an animal model for cystic fibrosis, CF). The acinar cells had elevated Mg and Ca and lowered K concentrations. Analysis of ultrathin cryosections showed high levels of Ca and Mg in secretory granules, mucus globules and the ER. Ca and Mg in the ER may be transported intracellularly with secretory proteins to secretion granules or mucus globules. The decrease in cell K may be due to efflux of K caused by elevated cytoplasmic Ca levels. A similar decrease in cell K was caused by incubation of rat salivary glands with diluted serum from CF patients, a treatment which has been reported to mimic the effect of a rise in cytoplasmic Ca.

• Research Organization: Department of Ultrastructure Research, Wenner-Gren Institute, University of Stockholm, Sweden
• OSTI ID: 5864802
• Journal Information: Scanning Electron Microsc.; (United States), Journal Name: Scanning Electron Microsc.; (United States); ISSN SEMYB
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400103* -- Radiometric & Radiochemical Procedures-- (-1987)
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ALKALINE EARTH METALS
BIOLOGICAL MATERIALS
BODY
BODY FLUIDS
CALCIUM
CHEMICAL ANALYSIS
DIGESTIVE SYSTEM
ELECTRON MICROPROBE ANALYSIS
ELEMENTS
ENDOCRINE GLANDS
GLANDS
MAGNESIUM
MATERIALS
METALS
MICROANALYSIS
ORGANS
PANCREAS
SALIVARY GLANDS
SECRETION