The effect of heat-stable Escherichia coli enterotoxin, theophylline and forskolin on cyclic nucleotide levels and mucosal surface (acid microclimate) pH in rat proximal jejunum in vivo

A T McKie, M Kusel, G T McEwan, M L Lucas

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Abstract

The normally acidic mucosal surface pH of 6.24 +/- 0.02(30) in rat proximal jejunum in vivo is effectively neutralised by 30 min exposure to heat-stable Escherichia coli (STa) enterotoxin (14 micrograms/ml) to 6.80 +/- 0.07 (n = 5) or to a forskolin/theophylline combination (1 mM:20 mM) to 7.10 +/- 0.07(7) while perfusion with Krebs-phosphate buffer alone without glucose left the mucosal surface pH unchanged at a pH of 6.21 +/- 0.02(9). Forskolin alone had no effect, and 20 mM theophylline moderately elevated the surface pH to 6.52 +/- 0.03(5). Theophylline, forskolin and their combination all elevated cAMP levels per mg tissue DNA above control values while STa enterotoxin was without effect. In contrast, all agents elevated cGMP levels per mg tissue DNA above control levels. These findings indicate that surface pH is only moderately affected by changes in cAMP levels and is affected to a much greater extent by altered cGMP levels.
Original languageEnglish
Pages (from-to)325-31
Number of pages7
JournalBiochimica et Biophysica Acta
Volume971
Issue number3
Publication statusPublished - 7 Oct 1988

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Microclimate
Enterotoxins
Cyclic Nucleotides
Colforsin
Jejunum
Theophylline
Hot Temperature
Escherichia coli
Acids
DNA
Buffers
Perfusion
Phosphates
Glucose

Keywords

  • Animals
  • Bacterial Toxins
  • Colforsin
  • Cyclic AMP
  • Cyclic GMP
  • Electric Conductivity
  • Enterotoxins
  • Escherichia coli Proteins
  • Hydrogen-Ion Concentration
  • Intestinal Mucosa
  • Jejunum
  • Kinetics
  • Rats
  • Rats, Inbred Strains
  • Reference Values
  • Theophylline

Cite this

@article{9cceb76fcd7049fb9f618ba21ba7f0e5,
title = "The effect of heat-stable Escherichia coli enterotoxin, theophylline and forskolin on cyclic nucleotide levels and mucosal surface (acid microclimate) pH in rat proximal jejunum in vivo",
abstract = "The normally acidic mucosal surface pH of 6.24 +/- 0.02(30) in rat proximal jejunum in vivo is effectively neutralised by 30 min exposure to heat-stable Escherichia coli (STa) enterotoxin (14 micrograms/ml) to 6.80 +/- 0.07 (n = 5) or to a forskolin/theophylline combination (1 mM:20 mM) to 7.10 +/- 0.07(7) while perfusion with Krebs-phosphate buffer alone without glucose left the mucosal surface pH unchanged at a pH of 6.21 +/- 0.02(9). Forskolin alone had no effect, and 20 mM theophylline moderately elevated the surface pH to 6.52 +/- 0.03(5). Theophylline, forskolin and their combination all elevated cAMP levels per mg tissue DNA above control values while STa enterotoxin was without effect. In contrast, all agents elevated cGMP levels per mg tissue DNA above control levels. These findings indicate that surface pH is only moderately affected by changes in cAMP levels and is affected to a much greater extent by altered cGMP levels.",
keywords = "Animals, Bacterial Toxins, Colforsin, Cyclic AMP, Cyclic GMP, Electric Conductivity, Enterotoxins, Escherichia coli Proteins, Hydrogen-Ion Concentration, Intestinal Mucosa, Jejunum, Kinetics, Rats, Rats, Inbred Strains, Reference Values, Theophylline",
author = "McKie, {A T} and M Kusel and McEwan, {G T} and Lucas, {M L}",
year = "1988",
month = "10",
day = "7",
language = "English",
volume = "971",
pages = "325--31",
journal = "Biochimica et Biophysica Acta",
issn = "0006-3002",
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TY - JOUR

T1 - The effect of heat-stable Escherichia coli enterotoxin, theophylline and forskolin on cyclic nucleotide levels and mucosal surface (acid microclimate) pH in rat proximal jejunum in vivo

AU - McKie, A T

AU - Kusel, M

AU - McEwan, G T

AU - Lucas, M L

PY - 1988/10/7

Y1 - 1988/10/7

N2 - The normally acidic mucosal surface pH of 6.24 +/- 0.02(30) in rat proximal jejunum in vivo is effectively neutralised by 30 min exposure to heat-stable Escherichia coli (STa) enterotoxin (14 micrograms/ml) to 6.80 +/- 0.07 (n = 5) or to a forskolin/theophylline combination (1 mM:20 mM) to 7.10 +/- 0.07(7) while perfusion with Krebs-phosphate buffer alone without glucose left the mucosal surface pH unchanged at a pH of 6.21 +/- 0.02(9). Forskolin alone had no effect, and 20 mM theophylline moderately elevated the surface pH to 6.52 +/- 0.03(5). Theophylline, forskolin and their combination all elevated cAMP levels per mg tissue DNA above control values while STa enterotoxin was without effect. In contrast, all agents elevated cGMP levels per mg tissue DNA above control levels. These findings indicate that surface pH is only moderately affected by changes in cAMP levels and is affected to a much greater extent by altered cGMP levels.

AB - The normally acidic mucosal surface pH of 6.24 +/- 0.02(30) in rat proximal jejunum in vivo is effectively neutralised by 30 min exposure to heat-stable Escherichia coli (STa) enterotoxin (14 micrograms/ml) to 6.80 +/- 0.07 (n = 5) or to a forskolin/theophylline combination (1 mM:20 mM) to 7.10 +/- 0.07(7) while perfusion with Krebs-phosphate buffer alone without glucose left the mucosal surface pH unchanged at a pH of 6.21 +/- 0.02(9). Forskolin alone had no effect, and 20 mM theophylline moderately elevated the surface pH to 6.52 +/- 0.03(5). Theophylline, forskolin and their combination all elevated cAMP levels per mg tissue DNA above control values while STa enterotoxin was without effect. In contrast, all agents elevated cGMP levels per mg tissue DNA above control levels. These findings indicate that surface pH is only moderately affected by changes in cAMP levels and is affected to a much greater extent by altered cGMP levels.

KW - Animals

KW - Bacterial Toxins

KW - Colforsin

KW - Cyclic AMP

KW - Cyclic GMP

KW - Electric Conductivity

KW - Enterotoxins

KW - Escherichia coli Proteins

KW - Hydrogen-Ion Concentration

KW - Intestinal Mucosa

KW - Jejunum

KW - Kinetics

KW - Rats

KW - Rats, Inbred Strains

KW - Reference Values

KW - Theophylline

M3 - Article

VL - 971

SP - 325

EP - 331

JO - Biochimica et Biophysica Acta

JF - Biochimica et Biophysica Acta

SN - 0006-3002

IS - 3

ER -