Preservation of the Effects of Pregnancy on Rat Islets of Langerhans in Tissue Culture

1979 ◽  
Vol 10 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Irene C. Green ◽  
Simon L. Howell ◽  
David Perrin
Keyword(s):  
Tissue Culture ◽  
Islets Of Langerhans ◽  
Rat Islets ◽  
Rat Islets Of Langerhans

Effects of cyclic AMP on DNA replication and protein biosynthesis in fetal rat islets of Langerhans maintained in tissue culture

1982 ◽  
Vol 2 (11) ◽  
pp. 867-876 ◽  
Author(s):  
I. Swenne
Keyword(s):  
Tissue Culture ◽  
Dna Replication ◽  
Cyclic Amp ◽  
Islets Of Langerhans ◽  
Protein Biosynthesis ◽  
Insulin Production ◽  
Rat Islets ◽  
Fetal Rat ◽  
Rat Islets Of Langerhans ◽  
Stimulation Of

The regulatory role of cyclic AMP (cAMP) in the growth and insulin production of the islet organ in vitro has been investigated. The effects of dibutyryl cyclic AMP (dbcAMP), theophylline, and 3-isobutyl-1-methylxanthine (IBMX) on DNA replication and on the biosynthesis of RNA and insulin in fetal rat islets of Langerhans maintained in tissue culture have been studied. Raising the glucose concentration from 2.7 mM to 16.7 mM caused a two-fold increase in DNA replication. Both dbcAMP and theophylline markedly inhibited the DNA replication at all glucose Concentrations studied. Low concentrations of IBMX stimulated DNA synthesis. However, at higher concentrations of this drug, known to considerably increase the islet cAMP levels, a marked inhibition of islet DNA replication was observed. Both (pro)insulin and total protein biosynthesis were stimulated by glucose, whereas dbcAMP stimulated only the (pro)insulin biosynthesis. Since glucose is known to raise islet intracellular levels of cAMP, which is known to be an inhibitor of cellular proliferation, the observed glucose stimulation of both islet-cell DNA replication and insulin production appeared conflicting. It is suggested that this dual effect of glucose may depend on a stimulation of proliferation in a limited pool of islet cells which may not exhibit an increase in cAMP.

scholarly journals Direct effects of progesterone on rat islets of Langerhans in vivo and in tissue culture

Diabetologia ◽  
1977 ◽  
Vol 13 (6) ◽  
pp. 579-583 ◽  
Author(s):  
S. L. Howell ◽  
Margaret Tyhurst ◽  
Irene C. Green
Keyword(s):  
Tissue Culture ◽  
Islets Of Langerhans ◽  
Direct Effects ◽  
Rat Islets ◽  
Rat Islets Of Langerhans

Opioid peptides in rat islets of Langerhans. Immunoreactive met- and leu-enkephalins and BAM-22P

Diabetes ◽  
1986 ◽  
Vol 35 (1) ◽  
pp. 52-57 ◽  
Author(s):  
K. I. Timmers ◽  
N. R. Voyles ◽  
C. King ◽  
M. Wells ◽  
R. Fairtile ◽  
...  
Keyword(s):  
Islets Of Langerhans ◽  
Opioid Peptides ◽  
Rat Islets ◽  
Rat Islets Of Langerhans

Effects of epicatechin on rat islets of Langerhans

Diabetes ◽  
1984 ◽  
Vol 33 (3) ◽  
pp. 291-296 ◽  
Author(s):  
C. S. Hii ◽  
S. L. Howell
Keyword(s):  
Islets Of Langerhans ◽  
Rat Islets ◽  
Rat Islets Of Langerhans

scholarly journals CYTOCHEMICAL LOCALIZATION OF ADENYL CYCLASE ACTIVITY IN RAT ISLETS OF LANGERHANS

1972 ◽  
Vol 20 (11) ◽  
pp. 873-879 ◽  
Author(s):  
S. L. HOWELL ◽  
MARGARET WHITFIELD
Keyword(s):  
B Cells ◽  
Islets Of Langerhans ◽  
Adenosine Triphosphate ◽  
Adenyl Cyclase ◽  
Cyclase Activity ◽  
Cytochemical Localization ◽  
Adenyl Cyclase Activity ◽  
Rat Islets ◽  
Rat Islets Of Langerhans ◽  
A And B Cells

A cytochemical method has been used to investigate the localization of adenyl cyclase activity in A and B cells of isolated rat islets of Langerhans. Adenosine triphosphate was initially utilized as substrate, the pyrophosphate liberated being precipitated by lead ions at its site of production. The specificity of the method was increased by the use of adenylyl-imidodiphosphate as an alternative substrate; this adenosine triphosphate analogue was not hydrolyzed by adenosine triphosphatase but provided an effective substrate for adenyl cyclase. Adenyl cyclase activity, which was found to retain its glucagon and fluoride sensitivity in glutaraldehyde-fixed tissue, was found exclusively and almost uniformly in the plasma membranes of A and B cells. Storage granule membrane, incorporated into the plasma membrane during secretion of the granule content by exocytosis, appeared to be devoid of adenyl cyclase activity.

scholarly journals Stimulation of Adenylate Cyclase by Ca2+ and Calmodulin in Rat Islets of Langerhans: Explanation for the Glucose-induced Increase in Cyclic AMP Levels

Diabetes ◽  
1980 ◽  
Vol 29 (1) ◽  
pp. 74-77 ◽  
Author(s):  
G. W. G. Sharp ◽  
D. E. Wiedenkeller ◽  
D. Kaelin ◽  
E. G. Siegel ◽  
C. B. Wollheim
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Islets Of Langerhans ◽  
Rat Islets ◽  
Rat Islets Of Langerhans ◽  
Stimulation Of

Immunological characterization of the guanine-nucleotide binding proteins Gi and Go in rat islets of Langerhans

1992 ◽  
Vol 8 (2) ◽  
pp. 103-108 ◽  
Author(s):  
N. S. Berrow ◽  
G. Milligan ◽  
N. G. Morgan
Keyword(s):  
G Proteins ◽  
Islets Of Langerhans ◽  
Pertussis Toxin ◽  
Nucleotide Binding ◽  
Molecular Forms ◽  
Antigenic Determinants ◽  
Guanine Nucleotide ◽  
Rat Islets ◽  
Guanine Nucleotide Binding ◽  
Rat Islets Of Langerhans

ABSTRACT Inhibition of insulin secretion from rat islets of Langerhans is known to involve at least one pertussis toxin-sensitive guanine-nucleotide binding (G) protein. We have used antisera raised against unique antigenic determinants of different members of the family of pertussis toxin-sensitive G proteins to identify these proteins in rat islets. Antiserum SG1, which recognizes both Gi1 and Gi2, reacted with an islet protein having an approximate Mr of 40 000. Antiserum IlC (Gi1 specific) failed to recognize any islet proteins, suggesting that Gi2 is present in much greater amounts than Gi1. Indeed, Gi1 levels were below the detection limit of a sensitive immunogold/silver-staining method, indicating that it may be absent from the cells of rat islets. Two different antisera were used to identify Go-like G proteins in rat islet homogenates. Both antisera reacted with a protein band which, under appropriate conditions, could be resolved to reveal two separate proteins of Mr 39–40 000. Thus, at least two molecular forms of Go are present in rat islets. Subcellular fractionation indicated that all three G proteins identified in this study (Gi2 and two forms of Go) are localized to islet membranes. No immunoreactivity could be detected in the cytosolic fraction.

Sign in / Sign up

Export Citation Format

Share Document