Discrepancy between effects of cholera toxin on net fluid movement and cAMP levels in rat jejunum, ileum, and colon

The effects of chloroquine diphosphate, a drug with "'membrane-stabilizing" properties, were studied on basal ileal absorption and on ileal secretion induced by increased intracellular cAMP levels and calcium (serotonin). The studies were performed on rat (in vivo) and rabbit ileum (in vitro). Intraluminal chloroquine (10(-4) M) reversed cholera toxin- and theophylline-induced secretion in rat ileum but did not alter the cholera toxin- and theophylline-induced increases in cAMP content. Addition of chloroquine (10(-4) M) to the mucosal surface of rabbit ileum did not alter basal active electrolyte transport or the serotonin-induced decreased Na and Cl absorption but inhibited the theophylline-induced C1 secretion. Addition of chloroquine (10(-4)) M) to the serosal surface stimulated net Na and Cl absorption. This effect may involve intracellular calcium. Chloroquine increased the rabbit ileal calcium content and decreased 45Ca2+ influx from the serosal surface. Both the mucosal and serosal effects of chloroquine described led to a net increase in absorptive function of the intestine and should prove useful in developing treatment of diarrheal diseases.

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Effect of cholera toxin on cAMP levels and Na+ influx in isolated intestinal epithelial cells

AJP Cell Physiology ◽

10.1152/ajpcell.1982.243.3.c107 ◽

1982 ◽

Vol 243 (3) ◽

pp. C107-C115 ◽

Cited By ~ 11

Author(s):

C. S. Hyun ◽

G. A. Kimmich

Keyword(s):

Cholera Toxin ◽

Secretory Activity ◽

Cellular Protein ◽

Intestinal Cell ◽

Intracellular Camp ◽

Intestinal Epithelial ◽

Isolated Cells ◽

Initial Exposure ◽

Mechanistic Basis ◽

Camp Levels

Freshly isolated chicken intestinal cells contain approximately 20 pmol adenosine 3',5'-cyclic monophosphate (cAMP)/mg cellular protein. Incubation with 3 micrograms/ml cholera toxin (CT) at 37 degrees C induces an elevation of cellular cAMP beginning 10-15 min after initial exposure. The response is linear with time for 40-50 min and causes a six- to eightfold increase over control levels at steady state. Dibutyryl cAMP and agents that increase cAMP production inhibit Na+ influx into the isolated enterocytes. Chlorpromazine completely abolishes the toxin-induced elevation of cAMP in the isolated cells and also reverses the effect on Na+ entry. The data provide evidence for a cAMP-mediated control of intestinal cell Na+ uptake, which may represent the mechanistic basis for the antiabsorptive effect of CT on Na+ during induction of intestinal secretory activity. Studies on the time-dependent effects of chlorpromazine on both intracellular cAMP concentration and Na+ influx suggest that the reactivation of the Na+ transport system after cAMP-induced inhibition is slow relative to the disappearance of cAMP.

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Altered pHi regulation and Na+/HCO3− transporter activity in choroid plexus of cilia-defective Tg737orpk mutant mouse

AJP Cell Physiology ◽

10.1152/ajpcell.00408.2006 ◽

2007 ◽

Vol 292 (4) ◽

pp. C1409-C1416 ◽

Cited By ~ 43

Author(s):

Boglarka Banizs ◽

Peter Komlosi ◽

Mark O. Bevensee ◽

Erik M. Schwiebert ◽

Phillip D. Bell ◽

...

Keyword(s):

Ion Transport ◽

Choroid Plexus ◽

Perinatal Period ◽

Ependymal Cells ◽

Intracellular Camp ◽

Transport Activity ◽

Wild Type ◽

Choroid Plexus Epithelium ◽

Fluid Movement ◽

Camp Levels

Tg737 orpk mice have defects in cilia assembly and develop hydrocephalus in the perinatal period of life. Hydrocephalus is progressive and is thought to be initiated by abnormal ion and water transport across the choroid plexus epithelium. The pathology is further aggravated by the slow and disorganized beating of motile cilia on ependymal cells that contribute to decreased cerebrospinal fluid movement through the ventricles. Previously, we demonstrated that the hydrocephalus phenotype is associated with a marked increase in intracellular cAMP levels in choroid plexus epithelium, which is known to have regulatory effects on ion and fluid movement in many secretory epithelia. To evaluate whether the hydrocephalus in Tg737 orpk mutants is associated with defects in ion transport, we compared the steady-state pHi and Na+-dependent transport activities of isolated choroid plexus epithelium tissue from Tg737 orpk mutant and wild-type mice. The data indicate that Tg737 orpk mutant choroid plexus epithelium have lower pHi and higher Na+-dependent HCO3− transport activity compared with wild-type choroid plexus epithelium. In addition, wild-type choroid plexus epithelium could be converted to a mutant phenotype with regard to the activity of Na+-dependent HCO3− transport by addition of dibutyryl-cAMP and mutant choroid plexus epithelium toward the wild-type phenotype by inhibiting PKA activity with H-89. Together, these data suggest that cilia have an important role in regulating normal physiology of choroid plexus epithelium and that ciliary dysfunction in Tg737 orpk mutants disrupts a signaling pathway leading to elevated intracellular cAMP levels and aberrant regulation of pHi and ion transport activity.

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cAMP modulates transepithelial resistance response of LLC-PK1 renal epithelia to tumor necrosis factor

AJP Renal Physiology ◽

10.1152/ajprenal.1995.268.2.f315 ◽

1995 ◽

Vol 268 (2) ◽

pp. F315-F322

Author(s):

C. W. Marano ◽

K. V. Laughlin ◽

L. M. Russo ◽

T. H. Short ◽

J. M. Mullin

Keyword(s):

Tumor Necrosis Factor ◽

Cholera Toxin ◽

Tumor Necrosis ◽

Cell Sheet ◽

Control Level ◽

Transepithelial Resistance ◽

Camp Content ◽

Leaky Epithelia ◽

Camp Levels ◽

Necrosis Factor

For "leaky" epithelia the transepithelial resistance (Rt) is an electrophysiological measure of the paracellular pathway within the epithelial barrier. The Rt across a monolayer of LLC-PK1 porcine renal epithelial cells is specifically an inverse measure of paracellular transepithelial permeability and displays a multiphasic and reversible response to the cytokine tumor necrosis factor-alpha (TNF). The Rt response to TNF can be inhibited by the nonhydrolyzable adenosine 3',5'-cyclic monophosphate (cAMP) analogue, dibutyryl-cAMP. In addition, activation of adenylate cyclase (forskolin) or inhibition of phosphodiesterase (3-isobutyl-1-methylxanthine, Ro-20-1724, and pentoxifylline), each of which have been reported to elevate cellular cAMP levels, also inhibited the Rt response to TNF. Incubation of the LLC-PK1 cell sheet with N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide, an inhibitor of cAMP-dependent protein kinase (PKA), potentiated the Rt response to TNF. The Rt response to TNF was completely prevented by preincubation of the cultures with cholera toxin, whereas pertussis toxin pretreatment had a slight but significant potentiating effect on the response. Pretreatment with cholera toxin was associated with an approximately 18-fold elevation in cAMP levels in both control and TNF-treated cultures. Measurements of cellular cAMP content at selected intervals after TNF administration showed a significant elevation (P < 0.01) of 140% above time-matched controls at 1 h after the administration of TNF to the cell sheet. The level of cAMP then declined to approximate control level within 2.5 h of TNF administration.(ABSTRACT TRUNCATED AT 250 WORDS)

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Effect of cholera toxin on passive transepithelial transport of 51 Cr-ethylenediaminetetraacetic acid and 14 C-mannitol in rat jejunum

Acta Physiologica Scandinavica ◽

10.1046/j.1365-201x.2001.00797.x ◽

2001 ◽

Vol 171 (2) ◽

pp. 153-160 ◽

Cited By ~ 3

Author(s):

B.-M. Fihn ◽

A. Sjöqvist ◽

M. Jodal

Keyword(s):

Cholera Toxin ◽

Ethylenediaminetetraacetic Acid ◽

Transepithelial Transport ◽

Rat Jejunum

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Proabsorptive effect of nitric oxide in cholera toxin- and 5-HT-induced fluid secretion in the rat jejunum in vivo

Gastroenterology ◽

10.1016/0016-5085(95)23756-9 ◽

1995 ◽

Vol 108 (4) ◽

pp. A274

Keyword(s):

Nitric Oxide ◽

Cholera Toxin ◽

Fluid Secretion ◽

Rat Jejunum

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COMPARATIVE ANALYSIS OF TIGHT JUNCTIONS OF EPITHELIUM OF RATS JEJUNUM UNDER THE EFFECT OF LIPOPOLYSACCHARIDE AND CHOLERA TOXIN

Journal of microbiology epidemiology immunobiology ◽

10.36233/0372-9311-2016-2-3-9 ◽

2016 ◽

pp. 3-9

Author(s):

O. N. Vishnevskaya ◽

O. V. Rybalchenko ◽

I. V. Larionov ◽

O. G. Orlova ◽

A. G. Markov

Keyword(s):

Comparative Analysis ◽

Cholera Toxin ◽

Tight Junctions ◽

Intercellular Space ◽

Rat Jejunum ◽

Cell Form ◽

Plasmatic Membrane ◽

Mucous Membranes ◽

Similar Character ◽

Ultrathin Sections

Aim. Comparative study of tight junctions and ultrastructure alterations of enterocytes of mucous membranes of jejunum of rats under the effect of lipopolysaccharides and cholera toxin. Materials and methods. Lipopolysaccharides (Sigma-Aldrich, Germany) and cholera toxin (Sigma-Aldrich, Germany) were used. The study was carried out in Wistar line rats. Effect of lipopolysaccharides and cholera toxin on epitheliocytes was carried out by a method of withdrawal of segments of rat jejunum and their incubation with the specified substances. Comparative analysis of ultrathin sections of enterocytes of jejunum of rats and tight junctions between them was carried out in control and under the effect of lipopolysaccharides and cholera toxin. Results. Effect of lipopoly-saccharides on ultrastructure of enterocytes of rat jejunum manifested in the change of cell form as a result of increase of intercellular space without destruction of tight junctions. Disappearance of desmosomes, increase of nuclei and more pronounced ER were noted in some epitheliocytes. Effect of cholerogen on epitheliocytes of mucous membrane of rat jejunum by a number of signs is similar to the effect of lipopolysaccharides, that manifested in an alteration of ultrastructure of cell, the form of those also transformed as a result of an increase of intercellular space, this process was not accompanied by destruction of tight junctions. Disappearance of folding of the lateral region of plasmatic membrane of cells and a reduction of a number of microvilli was observed under the effect of cholera toxin. Conclusion. A similar character of effect of lipopolysaccharides and cholera toxins on ultrastructure of cells and region of tight junctions of enterocytes of rat jejunum was detected, both substances caused an increase of intercellular space without the destruction of tight junctions.

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