Structural and functional changes by ethanol on in vitro guinea pig gastric mucosa

1986 ◽  
Vol 251 (4) ◽  
pp. G518-G528 ◽  
Author(s):  
M. J. Rutten ◽  
S. Ito
Keyword(s):  
Gastric Mucosa ◽  
Guinea Pig ◽  
Basal Lamina ◽  
Basal Cell ◽  
Morphological Changes ◽  
Short Circuit ◽  
Secretory Activity ◽  
Functional Changes ◽  
Ussing Chambers

Relationships between morphological and electrophysiological changes with low concentrations of ethanol on in vitro guinea pig gastric mucosa were investigated. Tissues mounted in Ussing chambers allowed recording of transepithelial potential difference (PD), resistance (R), short-circuit current (Isc), and acid secretion (H+). At selected times the mucosae were processed for morphological analysis. With luminal 10% ethanol there was a decrease in PD, R, Isc, and H+ within 1 min, and they eventually went to low steady-state values between 10 and 40 min. At 1 min many surface epithelial cells lifted off from the basal lamina but were still anchored by thin basal cell processes. After 10 min in ethanol many surface cells had completely detached from the basal lamina but remained connected to adjacent cells by their junctions. Numerous cytoplasmic blebs formed on both apical and basal cell surfaces. Concurrently, there was a significant increase in microvillus length. After 40 min most of the surface cells were detached from the basal lamina as sheets forming epithelial blisters. Upon ethanol washout there was epithelial cell reattachment to the basal lamina and a return of the PD, R, and Isc to control values within 40 min. Incubation of the luminal surface with 10% ethanol for 5 h resulted in a gradual rise of the PD, R, Isc, and H+ to control values by 4 h with a coincident return of the normal mucosal morphology. These studies indicate that ethanol has reversible and possibly adaptable effects on the in vitro guinea pig gastric mucosa and that the morphological changes are closely correlated with the decline and recovery of the electrical and secretory activity of the tissue.

scholarly journals Adrenergic activation of electrogenic K+ secretion in guinea pig distal colonic epithelium: desensitization via the Y2-neuropeptide receptor

2009 ◽  
Vol 297 (2) ◽  
pp. G278-G291 ◽  
Author(s):  
Jin Zhang ◽  
Susan T. Halm ◽  
Dan R. Halm
Keyword(s):  
Guinea Pig ◽  
Peptide Yy ◽  
Short Circuit ◽  
In Vitro Release ◽  
Surface Epithelium ◽  
Prostaglandin E ◽  
Bathing Solution ◽  
Ussing Chambers ◽  
Adrenergic Activation

Adrenergic activation of electrogenic K+ secretion in isolated mucosa from guinea pig distal colon was desensitized by peptide-YY (PYY). Addition of PYY or neuropeptide-Y (NPY) to the bathing solution of mucosae in Ussing chambers suppressed the short-circuit current ( Isc) corresponding to electrogenic Cl− secretion, whether stimulated by epinephrine (epi), prostaglandin-E2 (PGE2), or carbachol (CCh). Neither peptide markedly inhibited the large transient component of synergistic secretion (PGE2 + CCh). Sustained Cl− secretory Isc was inhibited ∼65% by PYY or NPY, with IC50s of 4.1 ± 0.9 nM and 9.4 ± 3.8 nM, respectively. This inhibition was eliminated by BIIE0246, an antagonist of the Y2-neuropeptide receptor (Y2-NpR), but not by Y1-NpR antagonist BVD10. Adrenergic sensitivity for activation of K+ secretion in the presence of Y2-NpR blockade by BIIE0246 was (EC50s) 2.9 ± 1.2 nM for epi and 13.3 ± 1.0 nM for norepinephrine, approximately fourfold greater than in the presence of PYY. Expression of mRNA for both Y1-NpR and Y2-NpR was indicated by RT-PCR of RNA from colonic mucosa, and protein expression was indicated by immunoblot. Immunoreactivity (ir) for Y1-NpR and Y2-NpR was distinct in basolateral membranes of columnar epithelial cells in the crypts of Lieberkühn as well as intercrypt surface epithelium. Adrenergic nerves in proximity with crypts were detected by ir for dopamine-β-hydroxylase, and a portion of these nerves also contained NPYir. BIIE0246 addition increased secretagog-activated Isc, consistent with in vitro release of either PYY or NPY. Thus PYY and NPY were able to suppress Cl− secretory capacity and desensitize the adrenergic K+ secretory response, providing a direct inhibitory counterbalance against secretory activation.

Aldosterone stimulates K secretion prior to onset of Na absorption in guinea pig distal colon

1994 ◽  
Vol 266 (2) ◽  
pp. C552-C558 ◽  
Author(s):  
D. R. Halm ◽  
S. T. Halm
Keyword(s):  
Guinea Pig ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Ussing Chambers ◽  
High Affinity Receptor ◽  
Additive Increase ◽  
K Secretion ◽  
Affinity Receptor

Distal colon from guinea pig was stimulated in vitro by aldosterone in Ussing chambers that allowed measurement of short-circuit current (Isc) and tissue conductance (Gt). The response to aldosterone was delayed by approximately 20 min and resulted in a negative Isc, consistent with K secretion. Approximately 1 h later the Isc began to increase and eventually became positive, consistent with subsequent stimulation of Na absorption. The Na-absorptive response could be inhibited by mucosal amiloride without altering the rate of K secretion. Similarly, K secretion could be inhibited by serosal bumetanide without altering Na absorption. In the presence of spironolactone, actinomycin D, or cycloheximide, aldosterone failed to stimulate both K secretion and Na absorption. A dose response to aldosterone provided an apparent Kd of 2.6 +/- 0.5 nM, consistent with a high-affinity receptor coupled to this secretory response. Stimulation by the K secretagogue epinephrine did not produce an additive increase in K secretion, suggesting that the same cell type responds to both aldosterone and epinephrine and that the protein induced by aldosterone was not one of the membrane proteins responsible for K secretion.

Stimulation of Cl- and HCO3- secretion by intramural cholinergic neurons in guinea pig antrum in vitro

1993 ◽  
Vol 264 (1) ◽  
pp. G118-G125 ◽  
Author(s):  
A. G. Suzuki ◽  
J. Kameyama ◽  
M. Tsukamoto ◽  
K. Kaneko ◽  
Y. Suzuki
Keyword(s):  
Guinea Pig ◽  
Short Circuit ◽  
Cholinergic Neurons ◽  
Short Circuit Current ◽  
Muscarinic Agonist ◽  
Serosal Side ◽  
Ussing Chambers ◽  
Bethanechol Chloride ◽  
Stimulation Of

Regulation of Cl- and HCO3- secretion by intramural cholinergic neurons was investigated in guinea pig antrum in vitro. Sheet preparations composed of the mucosa and the submucosa were mounted between Ussing chambers and bathed with buffer-free solution on the luminal surface and with HCO3(-)-CO2 solution on the serosal side. Short-circuit current (Isc), unidirectional fluxes of 36Cl and 22Na, and the luminal alkalinization rate (JOHSL) were determined. Electrical stimulation of the preparations elicited increases in both JOHSL and Isc, which were inhibited by tetrodotoxin (TTX) and atropine. Physostigmine also evoked TTX- and atropine-sensitive increases in JOHSL and Isc. Similar increases in JOHSL and Isc were observed when the muscarinic agonist bethanechol chloride (BCh) was added to the serosal side. The responses to BCh were not affected by TTX. The BCh-induced increase in JOHSL was largely abolished by removal of HCO3- or Na+ and addition of ouabain (serosal side) but was neither sensitive to Cl- removal nor associated with 22Na secretion. The increase in Isc induced by BCh was associated with the increase in 36Cl secretion and was inhibited by removal of Cl- or Na+ and by addition of bumetanide or ouabain (both, serosal side). These results suggest that the submucosal cholinergic neurons are involved via muscarinic receptors in the stimulation of epithelial HCO3- and Cl- secretion. For both HCO3- and Cl-, the cellular and membrane mechanisms of secretion induced by muscarinic stimulation, although not entirely clear, appear to be different from those occurring under baseline conditions.

Morphology and electrophysiology of guinea pig gastric mucosal repair in vitro

1983 ◽  
Vol 244 (2) ◽  
pp. G171-G182 ◽  
Author(s):  
M. J. Rutten ◽  
S. Ito
Keyword(s):  
Steady State ◽  
Guinea Pig ◽  
Morphological Analysis ◽  
Short Circuit ◽  
Isotonic Saline ◽  
Short Circuit Current ◽  
Electrical Parameters ◽  
Mucosal Repair ◽  
Ussing Chambers

Guinea pig gastric mucosae stripped of their outer muscle layers were studied in Ussing chambers for up to 14 h. Ten minutes after the mucosae were mounted in the chamber, the electrical parameters were low but continued to rise over 90 min until steady-state potential difference (PD), resistance (R), and short-circuit current (Isc) were recorded. Morphological analysis during the first 10 min of the tissue in the chamber revealed gaps in the epithelium due to damaged cells. However, tissues examined after 20 min in the chamber showed little evidence of epithelial discontinuity. Thereafter, the initial rise in the electrical parameters was noted. After steady-state attainment, the lumen was exposed to 1.25 M NaCl for 5 min and then changed back to 150 mM NaCl. Ten minutes after washout and return to control solutions, the PD, R, and Isc had fallen to low values. At 30 min after washout of the NaCl, the PD, R, and Isc began to increase and after 2 h were back to control values. Morphological analysis of mucosae fixed up to 10 min after exposure to 1.25 M NaCl showed extensive damage and exfoliation of surface cells. However, by 30 min the epithelium was restored and had very few discontinuities, which was then followed by the return of the electrical parameters. The conclusions from these studies are 1) guinea pig gastric mucosae exposed to hypertonic NaCl on the luminal side will primarily result in surface epithelial cell destruction with an immediate drop in the transepithelial electrical values; 2) after return to isotonic saline the damaged mucosa can repair itself within minutes, which then allows the reestablishment of the transepithelial electrical parameters by 2 h; and 3) the good viability and reproducibility of this preparation present a suitable mammalian model system for the study of factors of mucosal repair.

Protein kinase C potentiates cAMP-stimulated mouse duodenal mucosal bicarbonate secretion in vitro

2004 ◽  
Vol 286 (5) ◽  
pp. G814-G821 ◽  
Author(s):  
Bi-Guang Tuo ◽  
Jimmy Y. C. Chow ◽  
Kim E. Barrett ◽  
Jon I. Isenberg
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Duodenal Mucosa ◽  
Bicarbonate Secretion ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Ussing Chambers ◽  
Duodenal Bicarbonate Secretion

PKC has been shown to regulate epithelial Cl- secretion in a variety of models. However, the role of PKC in duodenal mucosal bicarbonate secretion is less clear. We aimed to investigate the role of PKC in regulation of duodenal mucosal bicarbonate secretion. Bicarbonate secretion by murine duodenal mucosa was examined in vitro in Ussing chambers using a pH-stat technique. PKC isoform expression and activity were assessed by Western blotting and in vitro kinase assays, respectively. PMA (an activator of PKC) alone had no effect on duodenal bicarbonate secretion or short-circuit current ( Isc). When PMA and dibutyryl-cAMP (db-cAMP) were added simultaneously, PMA failed to alter db-cAMP-stimulated duodenal bicarbonate secretion or Isc ( P > 0.05). However, a 1-h preincubation with PMA potentiated db-cAMP-stimulated duodenal bicarbonate secretion and Isc in a concentration-dependent manner (from 10-8 to 10-5M) ( P < 0.05). PMA preincubation had no effects on carbachol- or heat-stable toxin-stimulated bicarbonate secretion. Western blot analysis revealed that PKCα, -γ, -ϵ, -θ, -μ, and -ι/λ were expressed in murine duodenal mucosa. Ro 31–8220 (an inhibitor active against PKCϵ, -α, -β, and -γ), but not Gö 6983 (an inhibitor active against PKCα, -γ, -β, and -δ), reversed the potentiating effect of PMA on db-cAMP-stimulated bicarbonate secretion. PMA also time- and concentration-dependently increased the activity of PKCϵ, an effect that was prevented by Ro 31–8220 but not Gö 6983. These results demonstrate that activation of PKC potentiates cAMP-stimulated duodenal bicarbonate secretion, whereas it does not modify basal secretion. The effect of PKC on cAMP-stimulated bicarbonate secretion is mediated by the PKCϵ isoform.

Cellular pathways mediating tachykinin-evoked secretomotor responses in guinea pig ileum

1997 ◽  
Vol 273 (5) ◽  
pp. G1127-G1134 ◽  
Author(s):  
W. MacNaughton ◽  
B. Moore ◽  
S. Vanner
Keyword(s):  
Guinea Pig ◽  
Receptor Agonist ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Short Circuit Current ◽  
Neurokinin A ◽  
Guinea Pig Ileum ◽  
Cellular Pathways ◽  
20 Nm

This study characterized tachykinin-evoked secretomotor responses in in vitro submucosal and mucosal-submucosal preparations of the guinea pig ileum using combined intracellular and Ussing chamber recording techniques. Superfusion of endogenous tachykinins substance P (SP), neurokinin A (NKA), and neurokinin B depolarized single submucosal neurons and evoked increased short-circuit current ( I sc) responses in Ussing chamber preparations. The NK1-receptor agonist [Sar9,Met(O2)11]SP [50% effective concentration (EC50) = 2 nM] depolarized all submucosal neurons examined. The NK3-receptor agonist senktide (EC50 = 20 nM) depolarized ∼50% of neurons examined, whereas the NK2-receptor agonist [Ala5,β-Ala8]NKA-(4—10) had no effect on membrane potential. [Sar9,Met(O2)11]SP and senktide evoked similar increases in I sc that were tetrodotoxin sensitive (91 and 100%, respectively) and were selectively blocked by the NK1antagonist CP-99,994 and the NK3antagonist SR-142801, respectively. Capsaicin-evoked increases in I sc were significantly inhibited (54%, P < 0.05) by CP-99,994 but not by SR-142801. Neither antagonist inhibited slow excitatory postsynaptic potentials. These findings suggest that tachykinin-evoked secretion in guinea pig ileum is mediated by NK1 and NK3 receptors on submucosal secretomotor neurons and that capsaicin-sensitive nerves release tachykinin(s) that activate the NK1 receptors.

Alterations in capsaicin-evoked electrolyte transport during the evolution of guinea pig TNBS ileitis

2002 ◽  
Vol 282 (6) ◽  
pp. G972-G980 ◽  
Author(s):  
Paula Miceli ◽  
Gerald P. Morris ◽  
Wallace K. MacNaughton ◽  
Stephen Vanner
Keyword(s):  
Substance P ◽  
Guinea Pig ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Electrolyte Transport ◽  
Secretory Function ◽  
Trinitrobenzenesulfonic Acid ◽  
Ussing Chambers ◽  
Circulating Cytokines

The efferent secretomotor activity of capsaicin-sensitive nerves was monitored during the evolution of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced ileitis in the guinea pig by recording changes in short-circuit current (Δ I sc) in response to capsaicin, substance P (SP), and carbachol. Submucosal-mucosal preparations mounted in standard Ussing chambers were studied at time 0, at 8 h, and 1, 3, 5, 7, 14, and 30 days following the intraluminal instillation of TNBS or saline. Maximal Δ I scresponses to capsaicin were dramatically attenuated (54%) by 24 h. By day 7, SP- and TTX-insensitive carbachol-stimulated Δ I sc were also significantly reduced. Similar attenuation in capsaicin and carbachol responses was observed in jejunal tissue 20 cm proximal to the inflamed site at day 7. These studies demonstrate that efferent secretomotor function of capsaicin-sensitive nerves is maintained early in TNBS ileitis but significantly reduced by 24 h. By day 7, defects in enterocyte secretory function at inflamed and noninflamed sites also occurred, an effect that may be mediated by circulating cytokines.

Role of nutrient HCO3(-) in protection of amphibian gastric mucosa

1980 ◽  
Vol 239 (6) ◽  
pp. G536-G542
Author(s):  
R. Schiessel ◽  
A. Merhav ◽  
J. B. Matthews ◽  
L. A. Fleischer ◽  
A. Barzilai ◽  
...  
Keyword(s):  
Gastric Mucosa ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Experimental Conditions ◽  
Slow Decline ◽  
Alkaline Tide ◽  
Artificial Gastric Juice ◽  
Rapid Drop

In in vitro bullfrog fundic mucosa inhibited with 10(-3) M metiamide and exposed to a luminal pH of 2 a progressive slow decline in potential difference (PD) and short-circuit current (Isc) and a rise in resistance (R) were observed when the nutrient solution (N) contained 18 mM HCO3(-), but these changes were restored by an N containing 50 mM HCO3(-). Substitution of PO4(3-) or N-tris(hydroxymethyl)-methyl-2-aminoethanesulfonic acid for NHO3(-) in N caused a rapid drop in PD and Isc in inhibited tissues, changes that could be prevented by 10(-4) M histamine. Ulceration occurred more frequently in metiamide-inhibited gastric sacs exposed to artificial gastric juice with an N of 18 mMHCO3(-) than with 50 mM HCO3(-), but histamine prevented ulceration in the 18 mM HCO3(-) solution. JnetCl approximated Isc under most experimental conditions in inhibited mucosa and was reduced dramatically as were both Jn leads to sCl and Js leads to nCl when HCO3(-) was removed from N. In histamine-stimulated tissues, removal of nutrient HCO3(-) did not influence Cl- transport. Our results are consistent with the proposal that HCO3(-) in N supports normal Cl- flux and that the alkaline tide of actively secreting oxyntic cells can do the same in the absence of ambient HCO3(-).

Feeding induces lipid accumulation and increased Na+ transport in in vitro Necturus antrum

1990 ◽  
Vol 259 (6) ◽  
pp. G998-G1009
Author(s):  
M. J. Rutten ◽  
C. D. Moore ◽  
R. Delcore ◽  
L. Y. Cheung
Keyword(s):  
Electron Microscopy ◽  
Lipid Accumulation ◽  
Corn Oil ◽  
Short Circuit ◽  
Nile Red ◽  
Transepithelial Transport ◽  
Na Transport ◽  
Ussing Chambers ◽  
Lipid Granules

We investigated the effects of feeding on lipid accumulation and transepithelial transport using in vitro Necturus gastric antral mucosae. Antra from fed Necturi were examined for lipid accumulation using light, fluorescence, histochemical, and electron microscopy. Ussing chambers were used for measurement of potential difference (PD), transepithelial resistance (Rt), short-circuit current (Isc), and unidirectional fluxes of 22Na+ and [3H]mannitol. Light microscopy of antra from 2-day postfed animals showed many intracellular lipid granules in surface mucous epithelial cells. These granules could be distinguished from other intracellular organelles by their high affinity for osmium and the lipid fluorescent probe Nile red. Glycoprotein cytochemical staining showed these granules to be distinct from the epithelial cell mucous granules. Electron microscopy showed the lipid granules to be part of a membranous reticular network. Two-day postfed animals also had a approximately 3.5-fold increase in amiloride-sensitive Isc and PD, a decrease in Rt, and an increased luminal-to-serosal Na+ fluxes. Transepithelial [3H]mannitol fluxes were low and remained unchanged in both fasted and 2-day postfed animals. After 2 days of feeding, the PD and Isc began to decrease followed by a secondary increase in Rt. Feeding Necturi a corn oil diet did not induce the appearance of either cellular lipid or alterations in Isc but produced a transient increase in Rt. Our data show that feeding (goldfish) to Necturi causes an increase in both lipid accumulation and amiloride-sensitive Na+ transport in gastric antral cells.

Effects of ammonium ion and ammonia on function and morphology of in vitro frog gastric mucosa

1993 ◽  
Vol 265 (2) ◽  
pp. G277-G288 ◽  
Author(s):  
A. Yanaka ◽  
H. Muto ◽  
S. Ito ◽  
W. Silen
Keyword(s):  
Gastric Mucosa ◽  
Electrical Resistance ◽  
Rana Catesbeiana ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Ammonium Ion ◽  
Gastric Epithelial Cells ◽  
Sudden Drop ◽  
Oxynticopeptic Cells

The effects of ammonium ion (NH+4) and ammonia (NH3) on function and morphology of gastric epithelial cells were studied in intact sheets of in vitro frog (Rana catesbeiana) gastric mucosa. Luminal 115 mM NH4Cl at luminal pH 8.0 (calculated [NH3] 2.7 mM), but not at 5.0 (calculated [NH3] 3 microM) induced 1) an increase in intracellular pH (pHi) in oxynticopeptic cells (OPC) and decreases in transmucosal potential difference (PD) and electrical resistance (R) in resting tissues, 2) a decrease in histamine-stimulated H+ secretion and an increase in H+ backdiffusion after removal of luminal NH4Cl, and 3) augmented acidification of OPC during luminal acidification. Serosal 30 mM NH4Cl at serosal pH 7.2 (calculated [NH3] 0.47 mM) induced 1) an increase in pHi in OPC and inhibition of the alkalinization of OPC after removal of ambient Cl-, 2) a decrease in PD associated with the increase in R and decrease in short-circuit current, effects attenuated by serosal 15 mM K+, accentuated by 0.2 mM Ba2+, and abolished by removal of ambient Cl-, 3) a sudden drop of PD in resting, but not in stimulated tissues, effects prevented by high serosal pH (7.8), serosal HCO3-, or removal of luminal Cl-, 4) a decrease in histamine-stimulated H+ secretion and an increase in H+ backdiffusion after removal of NH4Cl, and 5) augmented acidification of OPC during luminal acidification. These results suggest that 1) luminal NH3, but not NH+4, increases backdiffusion of H+ from the lumen to the mucosa, 2) serosal NH3 and/or NH+4 induces depolarization of OPC and decreases electrogenic Cl- transport, thereby attenuating the activity of the basolateral Cl(-)-HCO3- exchanger in OPC, and 3) both of these effects contribute to the augmented acidification of OPC during exposure to high luminal [H+].

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