Saturation kinetics applied to in vitro effects of low prostaglandin E2 and F2α concentrations on ion transport across human jejunal mucosa

Like arachidonic acid (AA) and bradykinin (BK), the intrarenal administration of atrial natriuretic peptide (ANP) has been shown to increase the urinary excretion of prostaglandin E2 (PGE2). In the present study, the direct in vitro effects of ANP on PGE2 production were compared with those of AA and BK. Canine renal inner medullary slices were preincubated for 30 min and washed in aerated Krebs-Ringer buffer (37 degrees C). During the final incubation period, with the use of varied concentrations of AA, BK, or ANP in Krebs-Ringer buffer, samples were obtained at 0 and 30 min to be used for radioimmunoassay of PGE2. Although the rate of PGE2 production was significantly increased 11-fold with AA and threefold with BK, it was unaffected by four different doses of ANP (10(-5) to 10(-11) M). Furthermore, the production of PGE2 during basal and stimulated (BK or AA) conditions was significantly blocked by indomethacin but not by ANP. These results indicate that ANP had no direct stimulatory or inhibitory effect on the medullary production of PGE2.

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

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1982.243.1.g36 ◽

1982 ◽

Vol 243 (1) ◽

pp. G36-G41 ◽

Cited By ~ 6

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.

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In Vitro Effects of Prostaglandin E2 or Indomethacin on the Proliferation of Lymphokine-Activated Killer Cells and their Cytotoxicity against Bladder Tumor Cells in Patients with Bladder Cancer

Prostaglandins ◽

10.1016/s0090-6980(97)00161-5 ◽

1997 ◽

Vol 54 (5) ◽

pp. 769-779 ◽

Cited By ~ 10

Author(s):

Wang Zhiping ◽

Chen Yirong ◽

Zheng Rongliang ◽

Qin Dashan ◽

Chen Xuehong ◽

...

Keyword(s):

Bladder Cancer ◽

Prostaglandin E2 ◽

Tumor Cells ◽

Bladder Tumor ◽

Lymphokine Activated Killer Cells ◽

Killer Cells ◽

In Vitro Effects

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Systematic assessment of bone resorption, collagen synthesis, and calcification in chick embryonic calvaria in vitro: Effects of prostaglandin E2

Bone ◽

10.1016/8756-3282(93)90088-r ◽

1993 ◽

Vol 14 (4) ◽

pp. 655-659 ◽

Cited By ~ 8

Author(s):

M. Nagai ◽

Y. Suzuki ◽

M. Ota

Keyword(s):

Bone Resorption ◽

Prostaglandin E2 ◽

Collagen Synthesis ◽

Systematic Assessment ◽

In Vitro Effects

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

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1985.249.1.g113 ◽

1985 ◽

Vol 249 (1) ◽

pp. G113-G119 ◽

Cited By ~ 1

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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