Ion transport in rabbit ileal mucosa. I. Na and Cl fluxes and short-circuit current

Field, Michael; Fromm, David; McColl, Ian

doi:10.1152/ajplegacy.1971.220.5.1388

Cited by 251 publications

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“…The bathing solution was maintained at 37°C with water-jacketed reservoirs connected to a constant-temperature circulating pump and gassed with 95% 02/5% C02. Potential difference (PD) and short-circuit current (he) were measured, and tissue conductance (Ge) was calculated (17). Once the tissue reached equilibrium, 400 ,ul of <10-kDa culture ultrafiltrate was added to the mucosal side (time 0); 400 Al of the same sample was also added to the serosal side to preserve osmotic balance.…”

mentioning

confidence: 99%

Enteroaggregative Escherichia coli heat-stable enterotoxin 1 represents another subfamily of E. coli heat-stable toxin.

Savarino

Fasano

Watson

et al. 1993

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

245

195

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Enteroaggregative Escherichia coi (EAggEC) are associated with persistent diarrhea in young children. Some of these organisms produce a low-molecular-weight, heat-stable, plasmid-encoded enterotoxin that has been named EAggEC heat-table enterotoxin 1 (EAST1). We have cloned a 4.4-kb DNA fragment from the virulence plasmid of prototype EAggEC strain 17-2, which expresses enterotoxic activity as measured by electrogenic response in Ussing chambers mounted with rabbit ileal tissue. DNA-sequence analysis ofthis fragment identified an open reading frame (ORF) encoding a cysteine-rich polypeptide of 38 amino acids (Mr, 4100). Insertional and deletional mutations in this ORF resulted in loss of enterotoxic activity. The ORF was cloned into a T7 expression vector, and postinduction culture filtrates exhibited enterotoxic activity and increased ileal tissue cGMP levels. A synthetic peptide consisting of predicted amino acid residues 8-29 also showed enterotoxic activity. These data indicate that this ORF, named astA (EAggEC heat-table enterotoxin), represents the EASTI structural gene. EAST1 shows significant homology with the enterotoxic domain of heat-stable enterotoxin a (STa) of enterotoxigenic E. coil and with guanylin, a mammalian analog of STa. Unlike STa, which requires six cysteines and three disulfide linkages for ful biological activity, both EAST1 and guanylin contain four cysteine residues. Based on the cGMP data and the sequence homology to STa and guanylin, it is predicted that EAST1 stimulates the particulate form ofguanylate cyclase through the same receptorbinding region as STa and guanylin.

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mentioning

confidence: 99%

Enteroaggregative Escherichia coli heat-stable enterotoxin 1 represents another subfamily of E. coli heat-stable toxin.

Savarino

Fasano

Watson

et al. 1993

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

245

195

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“…The ionic composition of the Ringer's solution in mmol/liter was: Na+, 141; K+, 5; Ca 1.25; Mg2+, 1.1; Cl-, 125; HCO3-, 25; H2PO4-, 0.3; and HP042-, 1.65. The apparatus for measuring transmural electrical potential and short-circuit current (Isc) was similar to that previously described (13,14). Unidirectional and net Cl-fluxes were measured under short-circuit conditions as described (14).…”

mentioning

confidence: 99%

“…This article must therefore be hereby marked "advertisement" in accordance with 18 1.65. The apparatus for measuring transmural electrical potential and short-circuit current (Isc) was similar to that previously described (13,14). Unidirectional and net Cl-fluxes were measured under short-circuit conditions as described (14).…”

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confidence: 99%

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Control of guinea pig intestinal electrolyte secretion by a delta-opiate receptor.

Kachur

Miller

Field

1980

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

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The effects of opioids on transepithelial potential difference and short-circuit current across guinea pig ileum stripped of one muscle layer were measured in vitro in Ussing chambers. Opioid peptides such as [DA6a2, DMet5Jenkephalin, which are primarily agonists at -opiate receptors, were able to reduce transepithelial potential difference and short-circuit current at concentrations as low as 1 nM. The narcotic drug etorphine was also very potent in reducing short-circuit current, but fentanyl and morphine, which are primarily agonists at -opiate receptors, were almost complete y ineffective. Ketocyclazocine was relatively ineffective, and P-endorphin had intermediate potency.All opioid effects could be reversed by the opiate antagonist naloxone. Somatostatin also reduced short-circuit current, but its effect was not reduced by naloxone. Chloride flux measurements indicated that the effect of etorphine on short-Circuit current is associated with an enhancement of active Cl-absorption. The relative effects of opioids in this system suggest that their actions are being mediated by a specific 5-opiate receptor. In contrast, opioid effects on guinea pig intestinal smooth muscle seem to be primarily mediated by a i-opiate receptor.Opiates and opiate-like drugs such as diphenoxylate and loperamide are widely used in the treatment of diarrhea (1-4). Opiates are generally believed to produce their antidiarrheal action by stimulating intestinal circular muscle, thereby impeding the progress of material through the gut (5-7). In addition, in the guinea pig myenteric plexus, opioids also decrease the stimulated release of acetylcholine from cholinergic neurons. This action is the basis for a well established pharmacological assay for opiates (8). The recent discovery of the endogenous opioid peptides, the enkephalins, has provided a neuroanatomical basis for much of the classical pharmacology of the opiates (9). In particular, both [Met5]enkephalin and [Leu5]enkephalin have been found in intestinal enteric ganglia and in endocrine cells of the gut mucosa, suggesting a physiological role for the enkephalins in the gastrointestinal tract (10-12). One possibility is that they act as neurotransmitters and influence intestinal motility. Another possibility is that the enkephalins may have "paracrine" effects on the intestinal mucosa. Enkephalin released locally from endocrine cells or neuronal elements might act upon the intestinal mucosa to regulate the release of other bioactive substances or, more directly, the transport of ions across the mucosa. We have recently demonstrated that somatostatin may modulate electrolyte transport across rabbit ileal mucosa (13). The present paper demonstrates that opioids have an antisecretory effect on guinea pig mucosa. At the present time there is considerable discussion as to the possible existence of multiple opiate receptors. This would be analogous to the situation with acetylcholine, for example, where both nicotinic and muscarinic types of receptors The publication costs ...

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“…Dans un précédent travail (Licois, Coudert et Mongin, 1978a, Leitch, 1974), jéjunum (Fromm, Dibala et Sullivan, 1975), iléon (Field, Fromm et McColl, 1971 ;Schultz et Curran, 1974 ;Simmons et Naftalin, 1976) et colon (Frizzell, Koch et Schultz, 1976 ;Yorio et Bentley, 1977 figure 3 représente la quantité d'eau en fonction de la quantité de Na + , à potassium constant (R 2 = 0,954 ; n = 29) et fait apparaître des relations indépendantes eau-Na + et eau-K + puisque la corrélation sodium-potassium n'est pas significative (R 2 = 0,149).…”

Section: Introductionunclassified

Hypothèse sur la pathogénie de la diarrhée chez le lapin à partir de l'étude des contenus intestinaux

Licois¹,

Mongin²

1980

Reprod. Nutr. Dévelop.

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Ion transport in rabbit ileal mucosa. I. Na and Cl fluxes and short-circuit current

Cited by 251 publications

References 0 publications

Enteroaggregative Escherichia coli heat-stable enterotoxin 1 represents another subfamily of E. coli heat-stable toxin.

Enteroaggregative Escherichia coli heat-stable enterotoxin 1 represents another subfamily of E. coli heat-stable toxin.

Control of guinea pig intestinal electrolyte secretion by a delta-opiate receptor.

Hypothèse sur la pathogénie de la diarrhée chez le lapin à partir de l'étude des contenus intestinaux

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