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5′-AMP hydrolysis by suspensions and homogenates of pancreatic islet cells from normal and cortisone-treated rats

Lernmark, Å LU orcid ; Söderberg, L. A. LU and Täljedal, I. B. (1979) In Histochemistry 63(2). p.155-161
Abstract

Suspensions of endocrine pancreas cells were prepared by shaking collagenase-isolated rat islets of Langerhans in calcium-free buffer. When incubated with 1.0 mM substrate at pH 7.4, the cells split, Pi from 5′-AMP at a rate of 87 nmol/h per μg DNA, and from β-glycerophosphate at a rate of 25 nmol/h per μg DNA Km for 5′ AMP was about 54 μM. Adenosine or theophylline inhibited the 5′-AMP hydrolysis. Homogenization of the cells increased the activity toward 5′-AMP by 23% and that toward β-glycerophosphate by 115%. Injecting rats with cortisone had no effect on the 5′-AMP hydrolysis by whole cells but significantly increased the activity in cell homogenates; the intracellular activity toward 5′-AMP was more than... (More)

Suspensions of endocrine pancreas cells were prepared by shaking collagenase-isolated rat islets of Langerhans in calcium-free buffer. When incubated with 1.0 mM substrate at pH 7.4, the cells split, Pi from 5′-AMP at a rate of 87 nmol/h per μg DNA, and from β-glycerophosphate at a rate of 25 nmol/h per μg DNA Km for 5′ AMP was about 54 μM. Adenosine or theophylline inhibited the 5′-AMP hydrolysis. Homogenization of the cells increased the activity toward 5′-AMP by 23% and that toward β-glycerophosphate by 115%. Injecting rats with cortisone had no effect on the 5′-AMP hydrolysis by whole cells but significantly increased the activity in cell homogenates; the intracellular activity toward 5′-AMP was more than doubled by the cortisone treatment. Staining whole islet cells for 5′-AMP-splitting activity resulted in a demarcation of the cell periphery in control rats. Cells from cortisone-treated rats showed heavier deposits of reaction product, and their cell periphery did not stand out as clearly. It is suggested that 5′-nucleotidase is largely an ectoenzyme in normal rat islet cells. The cells also contain an as yet unidentified intracellular phosphatase that seems to be solely responsible for the increased hydrolysis of 5′-AMP in cortisone-treated rats.

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author
; and
publishing date
type
Contribution to journal
publication status
published
in
Histochemistry
volume
63
issue
2
pages
7 pages
publisher
Springer
external identifiers
  • pmid:387676
  • scopus:0018575232
ISSN
0301-5564
DOI
10.1007/BF00644537
language
English
LU publication?
no
id
4a0f6144-f746-4b81-88f2-b3cfeaec76ef
date added to LUP
2019-09-18 12:06:36
date last changed
2024-03-13 08:09:01
@article{4a0f6144-f746-4b81-88f2-b3cfeaec76ef,
  abstract     = {{<p>Suspensions of endocrine pancreas cells were prepared by shaking collagenase-isolated rat islets of Langerhans in calcium-free buffer. When incubated with 1.0 mM substrate at pH 7.4, the cells split, P<sub>i</sub> from 5′-AMP at a rate of 87 nmol/h per μg DNA, and from β-glycerophosphate at a rate of 25 nmol/h per μg DNA K<sub>m</sub> for 5′ AMP was about 54 μM. Adenosine or theophylline inhibited the 5′-AMP hydrolysis. Homogenization of the cells increased the activity toward 5′-AMP by 23% and that toward β-glycerophosphate by 115%. Injecting rats with cortisone had no effect on the 5′-AMP hydrolysis by whole cells but significantly increased the activity in cell homogenates; the intracellular activity toward 5′-AMP was more than doubled by the cortisone treatment. Staining whole islet cells for 5′-AMP-splitting activity resulted in a demarcation of the cell periphery in control rats. Cells from cortisone-treated rats showed heavier deposits of reaction product, and their cell periphery did not stand out as clearly. It is suggested that 5′-nucleotidase is largely an ectoenzyme in normal rat islet cells. The cells also contain an as yet unidentified intracellular phosphatase that seems to be solely responsible for the increased hydrolysis of 5′-AMP in cortisone-treated rats.</p>}},
  author       = {{Lernmark, Å and Söderberg, L. A. and Täljedal, I. B.}},
  issn         = {{0301-5564}},
  language     = {{eng}},
  month        = {{01}},
  number       = {{2}},
  pages        = {{155--161}},
  publisher    = {{Springer}},
  series       = {{Histochemistry}},
  title        = {{5′-AMP hydrolysis by suspensions and homogenates of pancreatic islet cells from normal and cortisone-treated rats}},
  url          = {{http://dx.doi.org/10.1007/BF00644537}},
  doi          = {{10.1007/BF00644537}},
  volume       = {{63}},
  year         = {{1979}},
}