PubMed Health⌕ Search

Biomedical subjects

H W Sampson

Publications and source records attributed to H W Sampson.

50 records · Page 3Linked to original sources
PubMed1983

Association of mitochondria with the plasma membrane of the acinar cells of actively secreting and nonsecreting rat lacrimal and parotid glands.

The distance between mitochondria and the nearest plasma membrane was measured in actively secreting and nonsecreting exocrine glands in order to determine the effect of the secretory mechanism upon mitochondrial distribution. The greatest accumulation of mitochondria was at 0.6 micron from the plasma membrane. No difference was noted in mitochondrial distribution of actively secreting, untreated and atropine-treated animals. There was also no difference in mitochondrial distribution of lacrimal and parotid acinar cells. The possible physiological significance of this observation is discussed.

Animals↗
PubMed1983

Calcium and parotid gland secretion: a cytochemical study.

Acinar cells of parotid glands from untreated, pilocarpine-treated, and atropine treated rats were studied, using a potassium pyroantimonate technique and X-ray microanalysis of calcium localization at the ultrastructural level. This was done in order to identify intracellular compartmentalisation of calcium and to elucidate any calcium translocation that might occur during the secretory process. Calcium pyroantimonate complexes were shown to be most prevalent on the plasma membrane of the non-secreting cells. These membranes gave up their calcium complexes during secretion. Conversely, the mitochondrial precipitates increased during secretion indicating an increase in intracellular calcium. The function of calcium in parotid gland secretion and the association of calcium with other cell structures are discussed.

Animals↗
PubMed1982

Intracellular calcium localization in stimulated and non-stimulated extraorbital lacrimal glands of rats.

Acinar cells of extraorbital lacrimal glands from control, pilocarpine-treated, atropine-treated and atropine + pilocarpine-treated rats were studied using a potassium pyroantimonate technique and X-ray microanalysis for calcium localization at the ultrastructural level. This was done in order to identify intracellular compartmentalization of calcium and to elucidate any calcium translocation that might occur during the secretory process. Calcium-pyroantimonate complexes were identified in the mitochondria, plasma membrane and cytoplasmic vesicles of the untreated specimens and in the plasma membrane of atropine-treated specimens, these complexes decreased drastically in the actively-secreting cells. The function of calcium in lacrimal gland secretion and the action of pilocarpine and atropine on membrane calcium are discussed.

Animals↗
PubMed1982

Intracellular calcium localization in stimulated, non-stimulated and repressed eccrine sweat glands.

Acinar cells of eccrine sweat glands from control, pilocarpine-treated, and atropine-treated rats were studied using a potassium pyroantimonate technique for calcium localization at the ultrastructural level. This was done in order to identify intracellular compartmentalization of calcium and to elucidate any calcium translocation that might occur during the secretion process. Calcium-pyroantimonate complexes were identified in the mitochondria, plasma membrane and cytoplasmic vesicles of the untreated and the atropine-treated specimens. These complexes decreased drastically in the actively secreting cells. The function of calcium in sweat gland secretion and the action of the utilized pharmacological agents on membrane calcium are discussed.

Animals↗
PubMed1981

Cytochemical analysis of intracellular distribution in the anterior pituitary of the rat.

In an attempt to assign morphologic identities to previously distinguished functional calcium compartments in the anterior pituitary of the rat, we employed the potassium pyroantimonate technique for cation localization. Tissues were incubated for 1 h at 37 degrees C in control medium; with 10 mM theophylline; or with depolarizing amounts of potassium. Precipitate was quantified on photomicrographs of tissue prepared for electron microscopy with a Talos Systems Digitizer. The nature of the electron dense precipitate was dependent on the experimental state of the tissue. Treatment with 5 mM EGTA abolished the dense precipitate. Electron microprobe analysis also confirmed that calcium was the predominant cation in the observed precipitate. The most significant changes in precipitate deposition occurred along the plasma membrane, the limiting membrane of secretory granules and within mitochondria. Dense precipitate was present along the plasma membrane only in cells treated with potassium. Control tissue exhibited higher levels of precipitate associated with the limiting membrane of secretory granules than either theophylline-treated or potassium-treated tissue. Mitochondria contained more precipitate in potassium-treated tissue than in controls, the mitochondria of theophylline-treated tissue contained intermediate levels of precipitate. Addition of either theophylline or depolarizing amounts of potassium has been associated with hormone secretion in anterior pituitary tissue of normal rats. Kinetic studies in our laboratory indicate that intracellular calcium shifts occur. The pyroantimonate technique is useful in verifying morphologically the calcium compartments involved in shifts in intracellular calcium.

Animals↗
PubMed1977

Effect of hypophysectomy on calcium transport by rat duodenum.

To examine the effect of hypophysectomy on intestinal calcium absorption, studies were performed on immature rats 7, 14, and 21 days after hypophysectomy. Duodenal calcium transport was measured in vitro utilizing everted gut sacs and in vivo by a luminal perfusion technique. Hypophysectomy produced no differences in the ability of everted gut sacs to transport calcium. Similarly, when in vivo transport data were expressed on the basis of intestinal length, no significant differences were noted. However, when transport data were expressed on the basis of mucosal weight, increases in absorption and lumen-to-plasma fluxes were apparent in hypophysectomized animals. No differences were seen in plasma-to-lumen fluxes. The results indicate that when the transport data are corrected for mass of intestinal mucosa, the duodenum from hypophysectomized animals absorbs calcium more avidly due to an increase in lumen-to-plasma flux.

Animals↗
PubMed1976

A morphometric investigation of the duodenal mucosa of normal, vitamin D-deficient, and vitamin D-replete rats.

Light and electron microscopy were utilized to determine differences in morphology and size in duodenal villi and microvilli from normal, vitamin D-deficient, and vitamin D-replete rats. An increase in villus diameter and surface area was observed in vitamin D-deficient rats. Administration of vitamin D reversed the increase in diameter but the height of villi increased resulting in longer, thinner villi without a significant change in surface area. A decrease in microvillus surface area seen in vitamin D-deficient animals was reversed by the administration of vitamin D.

Animals↗
PubMed1975

Effect of 1,25-dihydroxycholecalciferol on ethanol mediated suppression of calcium absorption.

Rats raised on laboratory diet and given 20% ethanol in water as a sole source of fluid for 12 days were given 0.2 mug of 1,25-dihydroxycholecalciferol 24 h before measuring duodenal calcium transport by an in vitro everted gut sac technique. This vitamin D metabolite did not reverse the ethanol-induced inhibitiom of transport capacity. Ultrastructural studies of intestinal epithelial cells from animals ingesting ethanol demonstrated changes in mitochondria and other subcellular organelles as well as accumulation of electron-dense, calcium-containing granules in microvilli and a paucity of granules in mitochondria. The results suggest that the inhibition is mediated at the intestinal level, affecting mechanisms which are probably independent of Vitamin D, and in part by an interference in transport of calcium from microvilli to other intracellular sites.

Animals↗