scholarly journals Effect of angiotensin II on ion transport across human Fallopian tube epithelial cells in vitro

Reproduction ◽  
2002 ◽  
pp. 573-579 ◽  
Author(s):  
T Mahmood ◽  
O Djahanbakhch ◽  
DE Burleigh ◽  
OA O'Mahony ◽  
GP Vinson ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Ion Transport ◽  
Fallopian Tube ◽  
Cultured Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Specific Sequence ◽  
Human Fallopian Tube

Angiotensin II type 1 receptors have been identified in Fallopian tube epithelia. Polarized confluent human Fallopian tube epithelial cell cultures were used under short-circuit conditions to study the actions of angiotensin II on electrogenic ion transport. The results demonstrate that angiotensin II increases baseline short-circuit current, implying a net transport of negatively charged ions from a basal to apical direction. This effect was inhibited by the selective angiotensin II type 1 receptor antagonist losartan. The effects of angiotensin II on short-circuit current were rapid in onset, brief in duration, and although less than those achieved with ATP, similar in amplitude to those described for other epithelia with angiotensin II. These findings reflect a significant retention of function for these cells in monolayer culture. Immunohistochemistry using the antibody 6313/G2, which is directed against a specific sequence in the extracellular domain of the angiotensin II type 1 receptor, confirmed that the receptor was retained in cultured cells. The results indicate that angiotensin II plays a role in regulating the composition of Fallopian tube secretions.

Avian cecum: role of glucose and volatile fatty acids in transepithelial ion transport

1991 ◽  
Vol 260 (5) ◽  
pp. G703-G710 ◽  
Author(s):  
B. R. Grubb
Keyword(s):  
Fatty Acids ◽  
Ion Transport ◽  
Volatile Fatty Acids ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Serosal Side ◽  
Na Transport ◽  
Cl Secretion ◽  
Mucosal Side

In the fowl cecum in vitro, the influence of glucose and the three most prevalent naturally occurring volatile fatty acids (acetate, propionate, butyrate) on short-circuit current (Isc), electrical resistance, and transport of Na and Cl was determined. When glucose, acetate, or butyrate was present, ion transport was characterized by electrogenic Na absorption, greater than 65% of which was amiloride inhibitable, and Cl secretion, which also was electrogenic. Isc could be completely accounted for by net fluxes of Na and Cl. When glucose, acetate, or butyrate (10 mM both sides) was included in the incubation medium, cecal tissue maintained its Isc and a constant rate of net Na absorption and Cl secretion for a 5-h period. When no substrate was present or propionate was included in the medium, a marked fall in Isc and net Na and Cl fluxes was seen. Glucose caused an increase in Isc when added only to the serosal side. As 3-O-methylglucose (not metabolized) was not effective in stimulating Isc of the cecum (serosal or mucosal addition), it appeared that glucose increased Isc by acting as an energy substrate for active Na transport. Acetate and butyrate appeared to be equally effective in stimulating Na transport and Isc when placed on either side of the membrane. When the preparation was supplied with glucose (serosal side) and acetate was added to the mucosal side, no further stimulation of Isc occurred. Thus it appeared that acetate and butyrate were acting as substrates for active Na transport rather than stimulating Na transport by some other mechanism such as a cotransport with Na.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of calcium on ion transport and electrical properties of tracheal epithelium

1978 ◽  
Vol 44 (6) ◽  
pp. 900-904 ◽  
Author(s):  
M. G. Marin ◽  
M. M. Zaremba
Keyword(s):  
Electrical Properties ◽  
Ion Transport ◽  
Calcium Concentration ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Tracheal Epithelium ◽  
Electrical Potential Difference ◽  
Tracheal Lumen

Active transport of Cl- toward the tracheal lumen and Na+ away from the lumen creates an electrical potential difference across dog tracheal epithelium. This study examined in vitro the effect of varying calcium concentration in the bathing media on the ion transport and electrical properties of dog tracheal epithelium. In six pairs of epithelia, changing calcium concentration from 1.9 to 0 mM resulted in a significant decrease in electrical resistance, from 318 +/- 36 to 214 +/- 24 omega.cm2. Short-circuit current and net Cl- and Na+ fluxes measured under short-circuit conditions were not changed significantly. Changing calcium concentration from 1.9 to 10 mM resulted in no significant change from control in the electrical properties nor in net Cl- and Na+ fluxes (short-circuit conditions). Histamine (10(-4) M) produced a significantly smaller increase in short-circuit current in 0 than in 1.9 mM Ca2+ (+5 +/- 2 vs. +12 +/- 2 microamperemeter/cm2). However, electrical changes were not significantly different in 1 or 10 mM Ca2+. These results indicate that calcium lack increased permeability of tracheal epithelium and that the increase in short-circuit current due to histamine depended in part on calcium.

Effect of theophylline and heat-stable enterotoxin of Escherichia coli on transcellular and paracellular ion movement across isolated porcine colon

1983 ◽  
Vol 61 (10) ◽  
pp. 1138-1148 ◽  
Author(s):  
R. A. Argenzio ◽  
S. C. Whipp
Keyword(s):  
Escherichia Coli ◽  
Ion Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Secretory Process ◽  
Anion Conductance ◽  
Heat Stable ◽  
Ion Movement ◽  
Transport Response

The effect of theophylline and a heat-stable enterotoxin of Escherichia coli (ST) on ion transport was examined using an in vitro, short-circuited preparation of the porcine colon. Theophylline abolished net Na absorption and elicited net Cl secretion, which quantitatively accounted for the increase in short-circuit current (Isc) observed. In contrast, a maximal dose of ST elicited an Isc response about one-half that of theophylline and only partially reduced the net absorption of Na and Cl. A significant residual ion flux, consistent with HCO3 secretion, was elicited by ST and was sustained after theophylline addition. Ion replacement experiments showed that the Isc and net ion transport response to ST was abolished when either Cl or HCO3 were removed from the bathing solutions. Voltage clamp experiments to evaluate the contribution of the paracellular and transcellular transepithelial pathways from serosa to mucosa showed that approximately one-half of the total serosa-to-mucosa flux (Jsm) of both Na and Cl was through the cells. Theophylline and ST both significantly reduced transcellular.[Formula: see text], but did not affect [Formula: see text]. Theophylline, but not ST, caused an increase in paracellular conductance of both ions. These results demonstrate significant differences in the effects of ST or theophylline on both transcellular and paracellular ion movement, and suggest that ST induces a Cl-dependent HCO3 secretion which is unobserved under control or theophylline-stimulated conditions. In addition, results are consistent with the operation of a neutral NaCl secretory process which is normally masked by the greater net rates of the neutral Na and Cl absorptive mechanisms. Thus, both ST and theophylline appear to reduce or abolish the neutral processes and convert the neutral secretory process into an electrogenic one. This latter effect could be explained simply by an increase in the anion conductance of the mucosal membranes.

Methylprednisolone increases absorptive capacity of rabbit ileum in vitro

1983 ◽  
Vol 245 (4) ◽  
pp. G562-G567 ◽  
Author(s):  
J. H. Sellin ◽  
R. C. DeSoignie
Keyword(s):  
Ion Transport ◽  
Absorptive Capacity ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Ion Flux ◽  
Rabbit Ileum ◽  
Transport Pathways ◽  
Na Pump ◽  
Intestinal Ion Transport

The effect of glucocorticoids on intestinal ion transport was studied in ileum in vitro from control and methylprednisolone (MP)-treated (40 mg im for 2 days) rabbits under the following conditions: a) basal rates of Na and Cl transport, b) the response to an individual absorptive stimulus (alanine, glucose, or epinephrine), and c) the response to a combination of the three absorptive stimuli. The results indicate that MP 1) increases basal absorption of Na and Cl and secretion of bicarbonate (as measured by residual ion flux), 2) does not alter the specific transport pathways stimulated by maximal doses of alanine, glucose, or epinephrine, but 3) significantly increases the absorptive capacity of ileum. After addition of combined alanine, glucose, and epinephrine, MP-treated ileum absorbed 15.8 mueq X cm-2 X h-1 Na (vs. 6.6 in controls, P less than 0.001) and 9.5 mueq X cm-2 X h-1 Cl (vs. 4.1 in controls, P less than 0.005). Additionally MP did not alter the Na dependence of either the short-circuit current or Cl absorption found in controls, although there appears to be a portion of residual ion flux insensitive to epinephrine inhibition. These data suggest that the MP-induced increase in absorptive capacity is due to an increase in a postapical transport step, most probably the Na pump.

NaCl transport across equine proximal colon and the effect of endogenous prostanoids

1990 ◽  
Vol 259 (1) ◽  
pp. G62-G69 ◽  
Author(s):  
L. L. Clarke ◽  
R. A. Argenzio
Keyword(s):  
Ion Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Proximal Colon ◽  
Nacl Transport ◽  
Apparent Lack ◽  
Ussing Chambers ◽  
Cl Secretion

In contrast to in vivo findings, the equine proximal colon fails to demonstrate significant net absorption of Na+ and Cl- under in vitro conditions. The present study was undertaken to determine if endogenous prostanoids are responsible for this apparent lack of ion transport. Proximal colonic tissues from ponies were preincubated in either normal Ringer solution or in Ringer containing 1 microM indomethacin and studied in Ussing chambers containing these solutions. Untreated colonic mucosa demonstrated negligible Na(+)-Cl- absorption in the basal state. In contrast, indomethacin-treated colon significantly absorbed Na+ and Cl-, primarily as the result of an equivalent increase in the mucosal-to-serosal flux of these ions. Preincubation of proximal colon in 0.1 mM ibuprofen-treated Ringer yielded similar results. Treatment of indomethacin colon with 1 mM mucosal amiloride eliminated net Na(+)-Cl- absorption without affecting the short-circuit current (Isc). The Isc in control tissue was significantly greater than in indomethacin-treated tissue and was reduced by 0.1 mM serosal furosemide. Serosal addition of 0.1 microM prostaglandin E2 or 10 mM serosal plus mucosal theophylline to indomethacin-treated tissues abolished net Na(+)-Cl- absorption and increased the Isc to levels indistinguishable from control. In contrast, control tissues were essentially unaffected by these secretagogues. These findings indicated that Na(+)-Cl- absorption in equine proximal colon was electroneutral (possibly involving Na(+)-H+ exchange) and that the tissue was capable of electrogenic Cl- secretion. However, under the in vitro conditions, basal ion transport was dominated by endogenous prostanoids that abolished Na(+)-Cl- absorption and elicited near-maximal electrogenic Cl- secretion.

Regulation of Na-Cl absorption in rabbit proximal colon in vitro

1987 ◽  
Vol 252 (1) ◽  
pp. G45-G51 ◽  
Author(s):  
J. H. Sellin ◽  
R. De Soignie
Keyword(s):  
Ion Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Proximal Colon ◽  
Beta Agonist ◽  
Disulfonic Acid ◽  
Low Concentrations ◽  
Cotransport System ◽  
Net Flux

Ion transport in rabbit proximal colon (PC) in vitro is dominated by a Na-Cl cotransport system stimulated by epinephrine. To further characterize the regulation of Na-Cl transport, we tested the effects of specific adrenergic agonists on ion fluxes under short-circuit conditions. Additionally, we tested the effects of the transport inhibitors bumetanide, furosemide, and 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS). Basal Na and Cl absorption were essentially nil [Na net flux (JNanet) = 0.3 +/- 0.4, and Cl net flux (JClnet) = -0.5 +/- 0.5 mu eq X cm-2 X h-1, means +/- SE]. The alpha 2-agonist clonidine significantly increased net Na and Cl absorption (delta JNanet = 3.0 +/- 0.6 mu eq X cm-2 X h-1, delta JClnet = 2.0 +/- 0.4 mu eq X cm-2 X h-1) with a minimal change in short-circuit current (delta Isc = 0.1 +/- 0.1 mu eq X cm-2 X h-1). The alpha 1-agonist phenylephrine and the beta-agonist isoproterenol did not alter ion transport. The alpha 2-blocker yohimbine (YOH) had a complex, concentration-dependent effect. At low concentrations (10(-6)-10(-8) M) YOH effectively inhibited epinephrine-stimulated cotransport. Compared with 10(-8)M YOH, 10(-6) YOH blocked 90% of the epinephrine-induced increases in Na and Cl absorption.(ABSTRACT TRUNCATED AT 250 WORDS)

cGMP modulation of ileal ion transport: in vitro effects of Escherichia coli heat-stable enterotoxin

1982 ◽  
Vol 243 (1) ◽  
pp. G36-G41 ◽  
Author(s):  
S. Guandalini ◽  
M. C. Rao ◽  
P. L. Smith ◽  
M. Field
Keyword(s):  
Escherichia Coli ◽  
Ion Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Rabbit Ileum ◽  
Heat Stable ◽  
Transport Effects ◽  
In Vitro Effects ◽  
Nonadditive Effects

Diarrheagenic strains of Escherichia coli have been shown to produce a heat-stable enterotoxin (ST) that simulates guanylate cyclase, increases short-circuit current (Isc), and inhibits active Cl absorption in the intestine. In rabbit ileum, the ion transport effects are smaller than those produced by cAMP-related agonists. Because ST may be a selective cGMP agonist, we further explored its mode of action in rabbit ileum. ST inhibits net Na and net Cl absorption. ST also inhibits the same fraction of Cl influx across the brush border that theophylline inhibits. At maximal doses, ST and 8-bromo-cGMP (8-Br-cGMP) had nearly equal, nonadditive effects of Isc that were about 66% of that produced by 8-Br-cAMP. ST increased mucosal cGMP concentration 16-fold, whereas epinephrine, an inhibitor of secretion, increased cGMP concentration by only 30%. This is insufficient to alter ion transport because doses of ST that increased cGMP concentration by 100% failed to alter Cl fluxes. Furthermore, epinephrine did not increase cGMP concentration in isolated enterocytes. We conclude that 1) cGMP mediates ST effects on ion transport, and 2) although ST and cAMP-related agonists have the same antiabsorptive effects, ST is less effective in stimulating electrogenic Cl secretion.

alpha 2-Adrenergic receptor regulation of ion transport in rabbit ileum

1982 ◽  
Vol 242 (3) ◽  
pp. G237-G242 ◽  
Author(s):  
E. B. Chang ◽  
M. Field ◽  
R. J. Miller
Keyword(s):  
Ion Transport ◽  
Adrenergic Receptor ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Maximal Effect ◽  
Rabbit Ileum ◽  
Ileal Mucosa ◽  
Receptor System ◽  
Alpha Adrenergic Receptors

Catecholamines are known to decrease short-circuit current (Isc), stimulate NaCl absorption, and inhibit HCO3 secretion in rabbit ileal mucosa in vitro. These effects appear to be mediated by alpha-adrenergic receptors because they are partially blocked by phentolamine and not by propranolol. To further characterize this receptor system, we determined the interactions of epinephrine (Epi) with alpha-subtype-selective antagonists. Prazosin (PZ), a specific alpha 1-antagonist, did not alter the Epi dose-response curve at concentrations up to 10(-5) M. Yohimbine (YO), a specific alpha 2-antagonist, completely inhibited the Epi effect on Isc. At 10(-5) M, YO increased by 70-fold the concentration of Epi required to produce a half-maximal effect (ED50; from 1.4 X 10(-7) M to 10(-5) M). YO and PZ by themselves had no significant effect on Isc in concentrations up to 10(-5) M. Clonidine, a specific alpha 2-agonist, decreased Isc with an ED50 similar to that of Epi; its effect was blocked by YO but not by PZ. Two alpha 1-selective agonists, methoxamine and phenylephrine, only caused a decrease in Isc in doses greater than 10(-5) M. This effect was reversed by YO but not by PZ. The effects of YO and PZ on Epi-modified Cl fluxes were also determined. YO completely aborted the effects of Epi on net Cl flux. No significant effects were seen with PZ. We conclude that the effects of Epi on ileal ion transport are mediated by a specific alpha 2-adrenergic receptor present in ileal mucosa and that no physiologic alpha 1-receptor function can be demonstrated.

Steroids alter ion transport and absorptive capacity in proximal and distal colon

1985 ◽  
Vol 249 (1) ◽  
pp. G113-G119 ◽  
Author(s):  
J. H. Sellin ◽  
R. C. DeSoignie
Keyword(s):  
Ion Transport ◽  
Absorptive Capacity ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Proximal Colon ◽  
High Rate ◽  
Transport Parameters ◽  
In Vitro Effects

Steroids are potent absorbagogues, increasing Na and fluid absorption in a variety of epithelia. This study characterizes the in vitro effects of pharmacological doses of gluco- and mineralocorticoids on transport parameters of rabbit proximal and distal colon. Treatment with methylprednisolone (MP, 40 mg im for 2 days) and desoxycortone acetate (DOCA, 12.5 mg im for 3 days) resulted in a significant increase in short-circuit current (Isc) in distal colon, suggesting an increase in basal Na absorption. Amiloride (10(-4) M) caused a significantly negative Isc in MP-treated tissue, demonstrating a steroid-induced, amiloride-insensitive electrogenic ion transport in distal colon. The effect of two absorbagogues, impermeant anions (SO4-Ringer) and amphotericin, were compared in control and steroid-treated distal colon. In controls, both absorbagogues increased Isc. Impermeant anions caused a rise in Isc in both MP and DOCA tissues, suggesting that the high rate of basal Na absorption had not caused a saturation of the Na pump. The steroid-treated colons, however, did not consistently respond to amphotericin. Amiloride inhibited the entire Isc in MP-treated distal colon that had been exposed to amphotericin; this suggested that amphotericin had not exerted its characteristic effect on the apical membrane of steroid-treated colon. In proximal colon, steroids did not alter basal rates of transport; however, epinephrine-induced Na-Cl absorption was significantly greater in MP-treated vs control (P less than 0.005). Steroids increase the absorptive capacity of both proximal and distal colon for Na, while increasing basal Na absorption only in the distal colon.(ABSTRACT TRUNCATED AT 250 WORDS)

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