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Biomedical subjects

T Barber

Publications and source records attributed to T Barber.

46 records · Page 3Linked to original sources
PubMed1975

Dispersed rat parotid acinar cells. I. Morphological and functional characterization.

Morphologically and functionally intact acinar cells have been obtained from the rat parotid gland through enzymatic dispersion with pure collagenase, hyaluronidase, and trypsin as well as mild mechanical forces. Cell yields of 30-50% of the original tissue weight with over 95% acinar cells were accomplished. The cells in suspension assumed a more or less spherical shape but the intracellular polarity of organelle distribution was maintained. The cells in suspension at 37 degrees C maintained stable monovalent cationic composition but lost potassium and gained sodium rapidly upon exposure to ouabain, 10(-5) M. The intracellular amylase concentration and the patterns of secretion of amylase and of synthesis of cyclic AMP by the cells in response to adrenergic stimulation with epinephrine or isoproterenol were comparable to those of the intact gland in situ. In addition, the cells showed good O2 consumption and maintained it constant for periods up to 8 h. These cells could be used as experimental tools for in vitro studies of receptor physiology and biochemistry, cell membrane function, cellular secretory mechanisms, and other parameters of exocrine gland cell physiology.

Amylases↗
PubMed1975

Dispersed rat parotid acinar cells. II. Characterization of adrenergic receptors.

The in vitro characterization of adrenergic receptors in isolated rat parotid acinar cells was accomplished through investigations of the transmembrane influxes of K and of the secretion of amylase in response to interactions of the cells with selected agonists and antagonists. Interaction of epinephrine (EPI) at concentrations of 10(-3)-10(-9) M with the alpha-adrenergic receptors resulted in rapid efflux of K from the cells. This effect was inhibited by phentolamine but not by propranolol or atropine. The process of secretion of amylase by these cells involved the activation of the beta-adrenergic receptors by the adrenergic agonists DL-isoproterenol (IPR) and EPI at similar to above concentrations. The interaction of these agonists with the beta receptors was inhibited by propranolol but not by phentolamine or atropine. Dibutyryl clclic AMP stimulated secretion of amylase at concentrations of 10(-8) M. A progressive increase in the secretory response of the cells was observed with increases in the dibutyryl cyclic AMP concentrations up to 10(-5) M. This effect was not inhibited by propranolol. This study demonstrates that dispersed rat parotid acinar cells have functionally intact adrenergic receptors and could be used as experimental tools for the studies of receptor physiology and pharmacology as well as other aspects of secretion at the cellular level.

Amylases↗
PubMed1975

Dispersed rat parotid acinar cells. III. Characterization of cholinergic receptors.

The in vitro characterization of cholinergic receptors in dispersed rat parotid acinar cells was accomplished through investigations of the net transmembrane fluxes of K in response to exposure of the cells to selected cholinergic agonists and antagonists. Interaction of acetylcholine bromide (ACh) and carbamylcholine (carbachol) with the cholinergic receptors resulted in rapid net efflux of K from the cells. This cellular response was demonstrable in concentrations of carbachol as low as 10(-8) M. With gradual increase in the concentrations of the agonist an increase in the K efflux was observed up to 10(-5) M. At higher concentrations of this cholinergic agonist no further increases in the net K efflux were observed. The response of the cells to cholinergic agonists was inhibited by atropine but not by the adrenergic antagonists phentolamine or propranolol, suggesting cholinergic agonist-antagonist interactions at the receptor site. The dispersed rat parotid acinar cells appear to have functionally intact cholinergic receptors and could be used as valuable experimental tools for the study of receptor physiology and pharmacology as well as of other aspects of secretory function at the cellular level.

Acetylcholine↗
PubMedDate not supplied

Extended storage of platelets in a new plastic container. I. Biochemical and morphologic changes.

A new polyvinyl chloride container plasticized with tri(2-ethylhexyl) trimellitate (PL 1240 plastic) was evaluated for use in extended platelet storage. Six leukocyte-rich platelet concentrates (mean, 0.6 X 10(9) white cells per bag; range, 0.3 to 1.0 X 10(9) per container) were prepared by removing as much of the platelet-rich plasma from blood as possible. The cells were stored at 22 degrees C on an end-over-end agitator. An average of 1.04 +/- 0.19 X 10(11) platelets was recovered, and the mean pH dropped from 7.23 on day 0 to 6.68 by day 5. At the completion of the storage period. PO2 averaged 80 torr, PCO2 was 35 torr, bicarbonate concentration was 0.5 mM, and lactate concentration 29.5 mM. Thirty-one additional units of platelet concentrates, not deliberately prepared to be leukocyte-rich, on day 5 had a pH of 6.75 +/- 0.39 (mean platelet yield, 0.97 +/- 0.21 X 10(11); PO2 and PCO2 averaged 50 and 48 torr, respectively). Following storage, the cells had an average phase microscopic morphology score of 244 (n = 17). Platelets appeared to be preserved well throughout storage when assessed by transmission and scanning electron microscopy. We conclude that platelets can be stored for 5 days in PL 1240 plastic containers with good preservation of pH and cell ultrastructure.

Benzoates↗
PubMedDate not supplied

Extended storage of single-donor platelet concentrate collected by a blood cell separator.

Use of a sealless blood pathway in a blood cell separator (CS-3000, Fenwal) permits collection of platelets in a "closed system" when saline and anticoagulant solutions are integrally attached; this in turn allows storage of instrument-collected platelet concentrates (PCs) beyond 24 hours. To evaluate extended storage of high yield PCs, cells collected with the instrument were stored (200 ml plasma) for 8 days (flatbed agitation) in either 3-liter polyvinylchloride (PL 146) containers (n = 6), polyolefin bags (PL 732) (n = 8), or two 1-liter polyolefin (double PL 732) containers (n = 8). A mean of 4.45, 4.09, and 3.94 X 10(11) platelets were stored in PL 146, single PL 732, and double PL 732, respectively; total white cells per container averaged 0.3, 0.2, and 0.2 X 10(9) for the three container systems. By day 1, platelet pO2 dropped to 14 and 16 torr in PL 146 and PL 732 PCs (pCO2, 127, and 82 torr). In contrast, double PL 732 maintained high pO2 (approximately equal to 80 torr) and low pCO2 (approximately equal to 30 torr) through day eight. Glucose declined at faster rates in PL 146 and single PL 732 containers, while lactate increased more rapidly (338 and 197 mg/dl of lactate on day four vs. 116 mg/dl for double PL 732 units). Morphology scores dropped from 400 to 98 (PL 146) and 216 (PL 732) at day four (pH values of 6.3 and 7.0), while a score of 330 was seen in double PL 732 PCs.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗
PubMedDate not supplied

The L-glutamate transporters GLAST (EAAT1) and GLT-1 (EAAT2): expression and regulation in rat lactating mammary gland.

The Na(+)-dependent L-glutamate transporters GLAST (EAAT1) and GLT-1 (EAAT2), were expressed in rat lactating mammary gland, but EAAC1 (EAAT3) was not. GLT-1 expression in rat lactating mammary gland was constant in all the physiological situations studied; however, the GLAST expression is under tight regulation. Fasting for 24 h decreased the GLAST expression which returned to control values after refeeding. Weaning for 24 h produced a decrease in GLAST expression through a mechanism independent of prolactin deficiency. Resuckling for 6 h returned the expression of this transporter to control values. There is a correlation between the levels of GLAST (mRNA and protein) and the in vivo uptake of L-glutamate by the lactating mammary gland during the starvation/refeeding cycle and milk accumulation process.

ATP-Binding Cassette Transporters↗