Secretion and Synthesis of Amylase in the Rat Parotid Gland after Isoprenaline

Byrt, Pauline N.

doi:10.1038/2121212a0

Cited by 93 publications

(20 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Experimental conditions, as described in Materials and Methods . Byrt (7) . The morophological changes during the secretory cycle, as observed by phase-contrast microscopy, are shown in Fig .…”

Section: Resultsmentioning

confidence: 99%

“…also reference 3) the lumen penetrates deeper into the cell until finally all the zymogen granules have been reached . The en- 7 …”

Section: Discussionmentioning

confidence: 99%

“…Evidence has also been discussed which indicates that epinephrine or norepinephrine is probably the physiological inducer of secretion acting upon release from adrenergic nerve fibers (5,6) . Byrt (7) recently showed that another catecholamine, isoprenaline, caused within 2 hr the secretion of more than 99"/c of the amylase which had been accumulated in the parotid gland of the rat . Synthesis of exportable protein was apparently unaffected, so that 16 hr later the glands again reached the original high level of accumulated amylase .…”

Section: Introductionmentioning

confidence: 99%

“…It was expected that such an investigation would establish the major changes in the gland cell structures and the time period during which they took place . Indeed, there was still doubt even about the first step of the secretion process in the rat parotid gland, since Rutberg (8), Scott and Pease (9), and Byrt (7) indicated that the content of the zymogen granules is discharged into the cell cytoplasm before secretion into saliva . The present work shows that when secretion is induced by isoprenaline in vivo, the lumen of the acinus becomes dramatically enlarged by progressive fusion of the cell membrane with the zymogen granule membrane .…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Dynamic Changes in the Ultrastructure of the Acinar Cell of the Rat Parotid Gland During the Secretory Cycle

Amsterdam

Ohad

Schramm

1969

The Journal of Cell Biology

417

129

View full text Add to dashboard Cite

Synchronization of the secretory cycle in vivo was obtained by injecting isoprenaline as an inducer of secretion . A quantitative correlation between enzyme release, its subsequent reaccumulation, and the sequence of ultrastructural changes was found . At the ultrastructural level secretion was paralleled by depletion of zymogen granules through fusion of the granule membrane with the lumen membrane and discharge of the content . Each zymogen granule membrane, once connected with the lumen, acted as a lumen membrane . Fusion was thus sequential and resulted in a dramatic enlargement of the lumen space . During the entire process the passage between the lumen and the intercellular space remained blocked by the tight junctions, as shown by their impenetrability to ferritin . Reduction of the lumen size following enzyme discharge seemed to be achieved by withdrawal of lumen membrane in the form of small smooth vesicles which appeared mostly in the apical part of the cell . At the same time, the cell retracted towards the lumen, the whole process being completed within 2 hr from onset of secretion . Disappearance of the smooth vesicle followed, concomitant with formation of many condensing vacuoles and appearance of mature zymogen granules . The fate of the zymogen granule membrane, including its fusion with the lumen membrane, resorption in the form of small smooth vesicles, and its eventual reutilization mediated by the Golgi system, is discussed .

show abstract

Section: Resultsmentioning

confidence: 99%

“…also reference 3) the lumen penetrates deeper into the cell until finally all the zymogen granules have been reached . The en- 7 …”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dynamic Changes in the Ultrastructure of the Acinar Cell of the Rat Parotid Gland During the Secretory Cycle

Amsterdam

Ohad

Schramm

1969

The Journal of Cell Biology

417

129

View full text Add to dashboard Cite

show abstract

“…Detailed investigations at the ultrastructural level in highly specialized and parenchymal cells have been limited, mainly because of the difficulties in preservation of antigenicity and this organelle's complicated morphology. We conducted an examination on the importance of the stacked structure and functions of the Golgi apparatus in the rat parotid acinar cell, because this cell type has the great advantage of containing highly developed and organized secretory components that are easily defined morphologically (Amsterdam et al 1969), and its excretion can be controlled by isoproterenol, an adrenergic ␤ -agonist (Byrt 1966;Simson et al 1974). As the existing mature secretory granules are entirely released from the cell immediately after isoproterenol injection, granules observed in the stimulated cell can be identified as newly formed.…”

mentioning

confidence: 99%

Structural Integrity of the Golgi Stack Is Essential for Normal Secretory Functions of Rat Parotid Acinar Cells: Effects of Brefeldin A and Okadaic Acid

Tamaki

Yamashina

2002

J Histochem Cytochem.

View full text Add to dashboard Cite

We examined the effects of specific inhibitors, brefeldin A (BFA) and okadaic acid (OA), on the ultrastructural organization of the Golgi apparatus and distributions of amylase, Golgi-associated proteins, and cathepsin D in the rat parotid acinar cells. BFA induced a rapid regression of the Golgi stack into rudimentary Golgi clusters composed of tubulovesicules, in parallel with a redistribution of the Golgi-resident proteins and a coat protein (β-COP) into the region of the rough endoplasmic reticulum (rER) or cytosol. The rapid disruption of the Golgi stack could also be induced by the effect of OA. However, redistribution of the Golgi proteins in rER or cytosol could not be observed and β-COP was not dispersed but was retained on the rudimentary Golgi apparatus. These findings suggested that the mechanism of OA in inducing degeneration of the Golgi stack was markedly different from that of BFA. In addition, missorting of amylase, a Golgi protein, and cathepsin D into incorrect transport pathways is apparent in the course of the disruption of the Golgi stack by OA. These Golgi-disrupting effects are reversible and the reconstruction of the stacked structure of the Golgi apparatus started immediately after the removal of inhibitors. In the recovery processes, missorting was also observed until the integrated structure of the Golgi apparatus was completely reconstructed. This suggested that the integrated structure of the Golgi apparatus was quite necessary for the occurrence of normal secretory events, including proper sorting of molecules.

show abstract

Evidence of cell damage in rat salivary glands after isoproterenol

Simson

1972

Anat. Rec.

View full text Add to dashboard Cite

Isoproterenol, which stimulates cell replication in rat salivary gland acinar cells also produces cytoplasmic disruption in these cells, although there is apparently little resultant cell death. Evidence of cell damage includes loss of cytoplasmic density, vesiculation of endoplasmic reticulum, appearance of large lipid droplets within cells, and invasion of the epithelium by lymphoid elements.The isoproterenol-stimulated rodent salivary gland is in current use as a model system of induced cell proliferation ('Barka, '65 a,b; Baserga and Heffler, '67; Malamud, '69; Pegoraro and Baserga, '70). Advantages of the system include the following : ( 1 ) it is a relatively synchronous ?n vivo system; ( 2 ) cell replication is induced by a single, chemically defined stimulus; and ( 3 ) only a single wave of cell replication is induced (Baserga, '66, '69; Baserga, Sasaki and Whitlock, '69). It has been assumed, on the basis of light .microscopic observations, that there is no (cell damage or necrosis after isoproterenol (van den Brenk, Sparrow and Moore, 70) although this is a concomitant of many other systems of in vivo stimulated cell replication, such as wound healing and partial hepatectomy.A disadvantage of the system is that isoproterenol also stimulates discharge of secretory material from the salivary glands (Byrt, '66), and the associated biochemical alterations are often difficult to dissociate from those related to stimulated cell replication. In a previous report on the process of secretion and restitution of secretory material in the rat parotid gland after isoproterenol (Simson, '69a) it was noted that, at certain times after isoproterenol, there was an increase in the number of cytoplasmic particles with the morphology of lysosomes in acinar cells. During the course of that study, other cellular alterations were noted which were not directly related to secretion and restitution of secretory material, but which may re-ANAT. REC , 173: 437-452.late to the stimulation of subsequent DNA synthesis. These alterations include evidence of cellular injury and the appearance of numerous macrophages and lymphoid cells within the gland (Simson, '69b). MATERIALS AND METHODSFemale Sprague-Dawley rats weighing 150 to 200 gm were given a single intraperitoneal injection of 5 mg isoproterenol in 0.2 ml water and were subsequently sacrificed at various time intervals. Uninjected animals were used as controls.Portions of both major salivary glands were removed from animals anesthetized with pentobarbital, care being taken not to use any portion of the glands that had been compressed by the forceps. The glands were placed in a drop of fixative and, using a very sharp razor blade, were minced into pieces no larger than 1 mme. The finely minced pieces were carefully transferred to a vial containing fixative and allowed to continue fixation for times ranging from one-half hour to four days. Various fixatives have been used, including formaldehyde-glutaraldehyde (Karnovsky, '65, modified either by decreasing the percentage...

show abstract

Secretion and Synthesis of Amylase in the Rat Parotid Gland after Isoprenaline

Cited by 93 publications

References 12 publications

Dynamic Changes in the Ultrastructure of the Acinar Cell of the Rat Parotid Gland During the Secretory Cycle

Dynamic Changes in the Ultrastructure of the Acinar Cell of the Rat Parotid Gland During the Secretory Cycle

Structural Integrity of the Golgi Stack Is Essential for Normal Secretory Functions of Rat Parotid Acinar Cells: Effects of Brefeldin A and Okadaic Acid

Evidence of cell damage in rat salivary glands after isoproterenol

Contact Info

Product

Resources

About