Bicarbonate transport in sheep parotid secretory cells.

Sheep parotid secretory cells contain an inwardly rectifying K+ conductance not seen in nonruminants. The channels underlying this conductance are highly active in unstimulated cells and, in consequence, have been implicated in spontaneous secretion (secretion in the absence of neural and hormonal stimulation), an unusual phenomenon seen conspicuously in ruminant parotid glands. Since spontaneous secretion by the sheep parotid first appears after weaning, at the same time that the parasympathetic secretomotor innervation becomes functional, and since parasympathetic denervation of the adult parotid causes spontaneous secretion to abate over a period of weeks, it might be expected that the activity of the inwardly rectifying K+ conductance would be similarly related to parasympathetic innervation if it plays an important role in spontaneous secretion. To test this hypothesis, we used whole cell patch-clamp techniques to study the inwardly rectifying K+ conductance in secretory cells from the parotid glands of unweaned lambs and normal adult sheep studied 6 wk after unilateral parotid parasympathectomy. The secretory cells from unweaned lambs showed almost no inwardly rectifying current, and the cells from parasympathectomized glands in adults showed a reduced current compared with the contralateral control glands. Our results thus provide evidence that the inwardly rectifying current is somehow enabled by the development of a functional parasympathetic innervation.

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Cation channels in basolateral membranes of sheep parotid secretory cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1992.263.5.g786 ◽

1992 ◽

Vol 263 (5) ◽

pp. G786-G794 ◽

Cited By ~ 5

Author(s):

E. A. Wegman ◽

T. Ishikawa ◽

J. A. Young ◽

D. I. Cook

Keyword(s):

Membrane Potential ◽

Relative Permeability ◽

Basolateral Membrane ◽

Cation Channels ◽

K Channel ◽

Secretory Cells ◽

K Channels ◽

Basolateral Membranes ◽

Sheep Parotid ◽

Relative Conductance

We observed 240-pS K+ channels in 63% of cell-attached patches, and 30-pS K+ channels were observed in 95% of cell-attached patches. The 240-pS K+ channel had the relative permeability sequence of K+ (1) = Rb+ (1) > Cs+ (0.3) >> Na+ (0.03) and the relative conductance sequence of K+ (1) > Rb+ (0.22) > Cs+ (0.05) > Na+ (0). It was activated by intracellular free Ca2+ and by depolarization. It was blocked by 10 mmol/l tetraethylammonium (TEA) applied extracellularly. The 30-pS K+ channel had the relative permeability sequence of K+ (1) = Rb+ (1) > Cs+ (> Na+ (< 0.09) and the relative conductance sequence of K+ (1) > Rb+ (0.45) > Cs+ (0) = Na+ (0). Its activity was not sensitive to cytosolic free Ca2+ or membrane potential, and it was not blocked by 10 mmol/l TEA extracellularly. Acetylcholine (10 mumol/l) activated the 240-pS voltage-activated and Ca(2+)-activated K+ channels but did not activate the 30-pS K+ channels. We conclude that the 30-pS K+ channel probably determines the properties of the basolateral membrane in unstimulated sheep parotid secretory cells, whereas the 240-pS voltage-activated and Ca(2+)-activated K+ channel may be important during parasympathomimetic stimulation.

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The ultrastructure of acinar cells in the external orbital gland of young and old male rats

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100082248 ◽

1978 ◽

Vol 36 (2) ◽

pp. 276-277

Author(s):

R. Carriere

Keyword(s):

Young Adulthood ◽

Acinar Cells ◽

Cell Number ◽

Male Rats ◽

Polyploid Cell ◽

Secretory Cells ◽

Age Changes ◽

Albino Rat ◽

Golgi Membranes ◽

Diploid Cells

The external orbital gland of the albino rat exhibits both sexual dimorphism and histological age changes. In males, many cells attain a remarkable degree of polyploidy and an increase of polyploid cell number constitutes the major age change until young adulthood. The acini of young adults have a small lumen and are composed of tall serous cells. Subsequently, many acini acquire a larger lumen with an irregular outline while numerous vacuoles accumulate throughout the secretory cells. At the same time, vesicular acini with a large lumen surrounded by pale-staining low cuboidal diploid cells begin to appear and their number increases throughout old age. The fine structure of external orbital glands from both sexes has been explored and in considering acinar cells from males, emphasis was given to the form of the Golgi membranes and to nuclear infoldings of cytoplasmic constituents.

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New Ultrastructural Observations on Injury and Regeneration of Cilia in Mammalian Conducting Airway Epithelium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100099544 ◽

1981 ◽

Vol 39 ◽

pp. 624-625

Author(s):

J.L. Carson ◽

A.M. Collier

Keyword(s):

Respiratory Tract ◽

Airway Epithelium ◽

Defense Mechanisms ◽

Normal Growth ◽

Fetal Lung ◽

Secretory Cells ◽

Airway Epithelial ◽

Ciliated Cells ◽

Conducting Airway ◽

Conducting Airways

The ciliated cells lining the conducting airways of mammals are integral to the defense mechanisms of the respiratory tract, functioning in coordination with secretory cells in the removal of inhaled and cellular debris. The effects of various infectious and toxic agents on the structure and function of airway epithelial cell cilia have been studied in our laboratory, both of which have been shown to affect ciliary ultrastructure.These observations have led to questions about ciliary regeneration as well as the possible induction of ciliogenesis in response to cellular injury. Classical models of ciliogenesis in the conducting airway epithelium of the mammalian respiratory tract have been based primarily on observations of the developing fetal lung. These observations provide a plausible explanation for the embryological generation of ciliary beds lining the conducting airways but do little to account for subsequent differentiation of ciliated cells and ciliogenesis during normal growth and development.

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Analysis of the Anterior Secretory Cells of Onchidohs Muricata (Nudibranchia)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100099490 ◽

1981 ◽

Vol 39 ◽

pp. 614-615

Author(s):

Roy Skidmore

Keyword(s):

Endoplasmic Reticulum ◽

Secretory Granules ◽

Golgi Body ◽

The Body ◽

Secretory Cells ◽

Secretory Vesicles ◽

High Magnification ◽

Large Numbers ◽

Membrane Bound ◽

Sole Of The Foot

The long-necked secretory cells in Onchidoris muricata are distributed in the anterior sole of the foot. These cells are interspersed among ciliated columnar and conical cells as well as short-necked secretory gland cells. The long-necked cells contribute a significant amount of mucoid materials to the slime on which the nudibranch travels. The body of these cells is found in the subepidermal tissues. A long process extends across the basal lamina and in between cells of the epidermis to the surface of the foot. The secretory granules travel along the process and their contents are expelled by exocytosis at the foot surface.The contents of the cell body include the nucleus, some endoplasmic reticulum, and an extensive Golgi body with large numbers of secretory vesicles (Fig. 1). The secretory vesicles are membrane bound and contain a fibrillar matrix. At high magnification the similarity of the contents in the Golgi saccules and the secretory vesicles becomes apparent (Fig. 2).

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