In vitro and in vivo effects of pancreozymin, urecholine, and cyclic AMP on rat pancreas

Morisset, J.; Webster, Peter

doi:10.1152/ajplegacy.1971.220.1.202

Cited by 78 publications

(24 citation statements)

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“…1 shows rates of incorporation of ["C]thymidine into pancreatic DNA. Under these conditions of in vitro incubation, incorporation was near linear for 30, 60, 90, 120, and 150 min.…”

Section: Resultsmentioning

confidence: 99%

“…of the metabolic chaniges observed in the pancreas after feeding can be initiated by administration of hormones of two types: neurohormones, for example acetylcholine, and gastrointestinal hormones, for example cholecystokinin-pancreozymin (CCK-PZ)1 and gastrin (1,2). Pancreatic protein synthesis, RNA synthesis, and phosph1o-lipid aand trigly ceride synthesis are initiated after adminiistration of these two types of hormones (1,3,4).…”

Section: Introductionmentioning

confidence: 99%

“…Pancreatic protein synthesis, RNA synthesis, and phosph1o-lipid aand trigly ceride synthesis are initiated after adminiistration of these two types of hormones (1,3,4).…”

Section: Introductionmentioning

confidence: 99%

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Hormonal Control of Pancreatic Growth

Mainz¹,

Black²,

Webster³

1973

J. Clin. Invest.

239

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A B S T R A C T Investigations have outlined pancreatic secretory and synthetic responses to gastrointestinal hormones. However, there is little information concerning hormonal influences on pancreatic growth.These studies were designed to examine effects of chronic administration of bethanechol and cholecystokinin-pancreozymin (CCK-PZ) on the pancreas. M\Iale albino rats were given saline, bethanechol, 6 mg/kg, or CCK-PZ, 20 U/kg, intraperitoneally twice daily and killed after 5 days. DNA was determined by the diphenylamine method using calf thymus DNA as a standard (20). RNA was determined by the orcinol method using ribose as a standard (21). Protein was determined by the biuret method using bovine serum albumin as the standard (22). Radioactivity was assayed in a Packard liquid scintillation counter (Packard Instrument Co., Inc., Downers Grove, Ill.) using a phosphor developed by Patterson and Greene (23). Fig. 1 shows rates of incorporation of ["C]thymidine into pancreatic DNA. Under these conditions of in vitro incubation, incorporation was near linear for 30, 60, 90, 120, and 150 min. Other investigators, using different tissues, have shown that thymidine nucleotide pools were small and that there was rapid equilibration between intracellular and extracellular thymidine pools (24). In addition, at concentrations of ["C]thymidine used in these experiments, no labeled ["C]thymidine triphosphate remained unincorporated in the cell (25). These observations were considered sufficient to validate the use of in vitro incubation of pancreas for short-term studies of DNA synthesis. A 90 min period of in vitro incubation was used for other experiments. RESULTS

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“…1 shows rates of incorporation of ["C]thymidine into pancreatic DNA. Under these conditions of in vitro incubation, incorporation was near linear for 30, 60, 90, 120, and 150 min.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Hormonal Control of Pancreatic Growth

Mainz¹,

Black²,

Webster³

1973

J. Clin. Invest.

239

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“…Reconciliation of these differing points of view has been provided by recent studies comparing effects of in vivo and in vitro administration of bethanechol chloride, cholecystokinin-pancreozymin, and cyclic AMP (20). In these studies, it was shown that administration of these agents in vivo was associated with initiation of both secretory and synthetic processes, whereas, administration of these agents in vitro was associated only with initiation of secretion.…”

Section: Discussionmentioning

confidence: 99%

Effects of Fasting and Feeding on Protein Synthesis by the Rat Pancreas

Morisset¹,

Webster²

1972

J. Clin. Invest.

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A B S T R A C T These experiments were designed to determine whether fasting and feeding were associated with differing rates of protein synthesis in the rat pancreas. It has been established that feeding, acetylcholine, or cholecystokinin-pancreozymin administration was associated with enhanced rates of digestive enzyme secretion; however, the literature is unclear as to effects of such stimulation on enzyme synthesis. Rats fed ad lib. or fasted 24, 48, or 72 hr were used for this study. Pancreases were removed and incubated in tissue culture medium with L-phenylalanine-"C, and incorporation into TCA-insoluble material as well as purified amylase was measured. Compared with fed controls, fasting 24, 48, and 72 hr was associated with 29%, 39%, and 35% decreases in incorporation of L-phenylalanine-14C into protein. Decreases of similar magnitudes were apparent whether the data were expressed in terms of protein or DNA. Pancreatic amylase isolated from rats fasted 48 hr contained 57% fewer counts of L-phenylalanine-'C than amylase isolated from fed rats. Moreover, rats fasted for 24 hr and given bethanechol chloride incorporated greater amounts of L-phenylalanine-1C into protein than fasted controls. Studies were performed to exclude changes in pool size of precursor (L-phenylalanine-"C) or product (amylase) in accounting for decreases associated with fasting. These studies demonstrate that fasting was associated with decreased rates of pancreatic amylase and protein synthesis in rats.

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“…Finally, after several hours in vitro and after the steady-state concentration of amylase had been attained in the medium, the system was still responsive to a cholinergic agonist that magnitudinally increased the flux of amylase into the bath. This large increase could not have been the result of a stimulus-induced increased amylase synthesis from cells compromised in some way to produce an "unnatural" amylase release into the bath, since cholinergic agents do not increase protein synthesis by pancreatic tissue in vitro to any substantial degree (20,21).…”

Section: (Iii)mentioning

confidence: 99%

Transport of alpha-amylase across the basolateral membrane of the pancreatic acinar cell.

Isenman¹,

Rothman²

1977

Proc. Natl. Acad. Sci. U.S.A.

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The flux of a-amylase (1,4-a-D-glucan glucanohydrolase; EC 3.2.1.1) across the basolateral membrane of the acinar cell was measured in the cell-to-bath direction using the whole rabbit pancreas in organ culture. This in vitro preparation is polarized so that apical and basolateral secretions can be collected separately. The unstimulated amylase flux from cell to bathwas substantial at the initial rate (approximately three times the concurrent apical flux). With time, bath amylase au proached a steady-state concentration, suggesting an equsiibrating process. During the same time interval, ductal amylase secretion remained constant. At the steady state, the amylase concentration in the bath was at least an order of magnitude less than its ductal concentration. HQurly replacement of bathing medium reproduced the initial rate of amylase release into the bath for five consecutive hours. Pancreozymin (cholecystokinin), a peptide hormone, did not alter the steady-state bath amylase content, although it greatly augmented ductal amylase secretion. In contrast, a cholinergc agonist greatly increased both the flux from the cell to bath and the ductal secretion of amylase. Taken together, these results indicate a natural bidirectional permeability of the basolateral membrane to digestive enzyme and support evidence previously obtained suggesting that such a permeability might exist. The interior of the pancreatic acinar cell is highly polarized; the rough-surfaced endoplasmic reticulum is located predominantly at the basal or blood-facing side of the cell, while the digestive enzyme-containing secretion granules, the zymogen granules, are concentrated at the cell's apex or its duct-facing surface. A functional analog of this anatomical polarization for the secretion of digestive enzymes is assumed in the popular hypothesis that new protein is synthesized at the basal portion of the cell and moved through a series of membrane-bound compartments to the apical surface, where it is secreted into the duct system by the exocytosis of zymogen granule contents. This construct has been called "vectorial transport" because it proposes that the movement of the secretory product is constrained to one direction, i.e., from the basal part of the cell to the duct lumen. In this formulation, only the apical membrane of the acinar cell allows the passage of digestive enzyme, and only in the cell-to-duct direction (1).Studies that have examined the kinetics of the secretory process directly are in conflict with this "vectorial transport" concept in a number of areas. Not only is the apical membrane apparently permeable in both the cell-to-duct and duct-to-cell direction (2), but similar bidirectional fluxes have been described for digestive enzyme across the zymogen granule membrane (3). Indeed, in this paper we present evidence that the basolateral (blood-facing) membrane of the cell also is bidirectionally permeable to these large molecules. In addition, the evidence suggests that these fluxes are all related by a cy-The costs of ...

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In vitro and in vivo effects of pancreozymin, urecholine, and cyclic AMP on rat pancreas

Cited by 78 publications

References 0 publications

Hormonal Control of Pancreatic Growth

Hormonal Control of Pancreatic Growth

Effects of Fasting and Feeding on Protein Synthesis by the Rat Pancreas

Transport of alpha-amylase across the basolateral membrane of the pancreatic acinar cell.

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