Biomedical subjects

B Kalley-Taylor

Publications and source records attributed to B Kalley-Taylor.

8 recordsLinked to original sources

PubMed1995

Regulation of eicosanoid synthesis in fibroblasts from inflamed gallbladders.

Gallbladder cell cultures obtained from rabbits subjected to sham or 72 h of bile duct ligation (72 h BDL, cholecystitis model) were incubated with calcium ionophore (A23187), dibutyryl cAMP (cAMP), and phorbol 12,13-diacetate (phorbol) to determine the intracellular signal transduction mechanisms responsible for increased inflamed gallbladder eicosanoid synthesis. Incubation of sham and 72 h BDL cell cultures with A23187 or phorbol significantly increased, whereas cAMP decreased, release of 6-keto-PGF1 alpha, PGE2, thromboxane B2 (measured by enzyme immunoassay) in a dose-related manner. Seventy-two-hour BDL cell cultures contained a specific 2-fold increased level of prostacyclin synthase compared to sham cell cultures which was not altered by preincubation with A23187, phorbol or cAMP. These findings suggest that increased PGI2 release in the sham and inflamed cell cultures following A23187 and phorbol stimulation was mediated in part via the inositol triphosphate pathway and protein kinase C activation and was not associated with altered cyclooxygenase or prostacyclin synthase content.

6-Ketoprostaglandin F1 alpha↗

PubMed1995

Platelet activating factor (PAF) stimulates release of PGI2 from inflamed rabbit gallbladder cell cultures.

This study examines the hypothesis that PAF stimulates release of PGI2 from inflamed rabbit gallbladder explant cell cultures. New Zealand white rabbits underwent bile duct ligation for 72 h (72 h BDL), or sham operation, Sham and 72 h BDL gallbladder explants were placed in culture, and the cells grown to 75% confluence. The cells were exposed to increasing concentrations of PAF for 60 min. The media analyzed for eicosanoid release by EIA and the cells analyzed for cyclooxygenase and prostacyclin synthase content by immunoblot analysis. PAF increased release of 6-keto-PGF1 alpha from the 72 h BDL gallbladder cell cultures in a dose-related manner which was inhibited by indomethacin preincubation by 90%. The increased 72 h BDL cell release of 6-keto-PGF1 alpha was not associated with changes in the content of cyclooxygenase or prostacyclin synthase. PAF did not alter eicosanoid release from sham control cell cultures. These data suggest that PAF can only up-regulate endogenous 6-keto-PGF1 alpha release from the 72 h BDL cells that had been previously stimulated by inflammation. PAF may thus contribute to gallbladder distention and injury by chronic stimulation of inflamed gallbladder PGI2 release.

6-Ketoprostaglandin F1 alpha↗

PubMed1995

Taurodeoxycholic acid stimulates rabbit gallbladder eicosanoid release.

Rabbit common bile duct ligation has been shown to concomitantly increase levels of gallbladder taurodeoxycholic acid and gallbladder eicosanoid release. This study examines the hypothesis that taurodeoxycholic acid, a known chemical mediator of gallbladder inflammation, stimulates endogenous gallbladder eicosanoid release. Male New Zealand white rabbits were anesthetized, gallbladders removed and perfused in vitro with Krebs-Henseleit buffer (pH 7.4, 37 degrees C) at 1 ml/min with increasing doses of taurodeoxycholic acid (0, 10, 30 and 100 mM) added to the perfusate. The effluent was collected at 15, 30, 60 and 120 min of perfusion and assayed for 6-keto-PGF1 alpha (PGI2 metabolite), PGE2, and thromboxane B2 (TXB2) by enzyme immunoassay. Taurodeoxycholic acid increased gallbladder eicosanoid release in a dose-related manner with 6-keto-PGF1 alpha and PGE2 release 10-fold higher than TXB2. Indomethacin (1.5 mM) decreased gallbladder eicosanoid release by 50% in the gallbladders perfused with 30 mM taurodeoxycholic acid, demonstrating that the increased gallbladder eicosanoid release was due to de novo synthesis. These findings suggest that the increased release of gallbladder PGI2 and PGE2 described in animal models of cholecystitis may, in part, be related to increased gallbladder bile levels of taurodeoxycholic acid.

6-Ketoprostaglandin F1 alpha↗

PubMed1994

Increased intragallbladder pressure stimulates gallbladder eicosanoid release.

The stimulus for increased gallbladder eicosanoid synthesis during cholecystitis is unknown. This study examines the hypothesis that increased intragallbladder pressure stimulates endogenous gallbladder eicosanoid release. Rabbit gallbladders were perfused in vitro at 1 ml/minute with oxygenated Krebs-Henseleit buffer and subjected to 0, 12 or 24 mm Hg of intraluminal gallbladder pressure. Release of 6-keto-PGF1 alpha infinity PGE2 and thromboxane B2 were measured in all groups after 15 and 30 and 60 minutes of perfusion by enzyme immunoassay and gallbladders were examined histologically. Increasing intraluminal gallbladder pressure concomitantly increased gallbladder 6-keto-PGF1 alpha release 2 fold or more at all time of perfusion and altered gallbladder mucosal architecture by increasing basolateral edema in the submucosal space. Infusion of indomethacin (10 micrograms/ml in the perfusion media) decreased 6-keto-PGF1 alpha release from the in vitro perfused gallbladders subjected to 24 mm Hg by 70%. Increased gallbladder eicosanoid release during early cholecystitis may in part be related to the physical force of increased gallbladder intraluminal pressure on the gallbladder mucosa.

6-Ketoprostaglandin F1 alpha↗

PubMed1993

The role of prostaglandin I2 and biliary lipids during evolving cholecystitis in the rabbit.

BACKGROUND: Acute cholecystitis increases gallbladder prostanoid synthesis. The percent study examined the hypothesis that increased endogenous gallbladder release of prostaglandin I2 (PGI2) after bile duct ligation is caused by both increased ductal pressure and altered biliary lipids. METHODS: Prostanoid release, biliary lipids, and in vitro fluid absorption of sham gallbladders were compared with those of gallbladders in which acute cholecystitis was induced after common bile duct ligation for 6, 24, and 72 hours. RESULTS: Bile duct ligation for 6, 24, and 72 hours increased gallbladder PGI2 release twofold and increased gallbladder bile levels of lysolecithin and taurine-conjugated bile acids fivefold compared with sham groups (P < 0.05). In vitro gallbladder fluid absorption was decreased by 50% or more in the 6-, 24-, and 72-hour bile duct-ligated groups (P < 0.05) but was reversed by indomethacin only in the 6-hour ligated group. CONCLUSIONS: Decreased gallbladder fluid absorption following bile duct ligation for 6 hours was caused by increased gallbladder release of PGI2. Decreased gallbladder fluid absorption following bile duct ligation for 24 and 72 hours was not a prostanoid-mediated process (not reversed by indomethacin) but was associated with increased bile levels of proinflammatory biliary lipids.

Absorption↗

PubMed1993

Acute cholecystitis potentiates bradykinin stimulated fibroblast prostanoid release in the rabbit.

Gallbladder explants from control rabbits and rabbits subjected to bile duct ligation (BDL) for 24 and 72 h (cholecystitis model) were placed in cell culture to determine the source for increased gallbladder prostanoid synthesis during cholecystitis. Cultures from control and 24 h BDL gallbladders grew spindle shaped fibroblasts which did not exhibit increased prostanoid synthesis. 72 h BDL gallbladder cell cultures grew large polygonal shaped cells which appeared to be 'stimulated fibroblasts' by light and electron microscopy and were associated with increased basal and bradykinin stimulated 6-keto-PGF1 alpha release and increased content of prostacyclin synthase when measured by enzyme immunoassay and protein immunoblot analysis respectively. Use of bradykinin antagonists showed that the bradykinin BK2 subtype receptor was the most prominent in the 72 h BDL cell cultures. The 'stimulated fibroblasts' were the source of bradykinin stimulated gallbladder 6-keto-PGF1 alpha synthesis in the inflamed rabbit gallbladder which was mediated by the bradykinin B2 subtype receptor.

6-Ketoprostaglandin F1 alpha↗

PubMed1992

Increased gall-bladder prostanoid synthesis after bile-duct ligation in the rabbit is secondary to new enzyme formation.

Ligation of the common bile duct (BDL) in the male rabbit resulted in increased gall-bladder microsomal total cyclo-oxygenase activity with prostaglandin E2 (PGE2) and 6-oxoprostaglandin F1 alpha [6-oxo-PGF1 alpha, stable metabolite of prostaglandin I2 (PGI2; prostacyclin)] as the major prostanoids synthesized after 24 and 72 h. Kinetic analysis of gallbladder microsomal membrane fractions incubated with increasing levels of [14C]arachidonic acid indicated that BDL for 24 and 72 h did not change substrate affinity (apparent Km) but markedly increased the rate of conversion (apparent Vmax.) suggesting the presence of more total enzyme responsible for synthesis of 6-oxo-PGF1 alpha and PGE2. BDL for 24 and 72 h significantly increased gall-bladder tissue slice basal release of 6-oxo-PGF1 alpha, but not PGE2, when compared with the controls. Gall-bladder slice release of PGE2 was 3-fold less than 6-oxo-PGF1 alpha in the control gall-bladder slices. Immunoblot analysis of 72 h BDL gall-bladder microsomal membrane fractions showed a slight increase in cyclo-oxygenase content and a 5-fold increase in the content of prostacyclin synthase as compared with the control. These data suggest that the BDL-stimulated total gall-bladder cyclo-oxygenase activity was the result of an increase in the level of specific prostaglandin-synthetic enzymes, in particular prostacyclin synthase, and not from a change in enzyme affinity.

Animals↗

PubMed1992

Bradykinin and not cholecystokinin stimulates exaggerated prostanoid release from the inflamed rabbit gallbladder.

The relationship of bradykinin and cholecystokinin (CCK) to inflamed gallbladder prostanoid synthesis and release was examined in rabbits treated with common bile duct ligation (BDL) for 24 or 72 h. Gallbladders removed from control and BDL groups were incubated in oxygenated Krebs buffer at 37 degrees C (pH 7.4) for 60 min. The slices were then placed every 20 min in vials containing increasing doses of bradykinin (30-3000 ng) or CCK (30-1000 ng). Incubation fluid was analyzed by RIA for 6-keto-prostaglandin (PG)F1 alpha (PGI2 metabolite), PGE2 and thromboxane (TX) B2. Bradykinin stimulated control gallbladder 6-keto-PGF1 alpha and PGE2 release was modest. Gallbladders from 24- and 72-h BDL groups released 3- to 10-fold higher levels of 6-keto-PGF1 alpha and PGE2 (not TXB2) following bradykinin stimulation when compared to controls, which was abolished with indomethacin pretreatment. CCK did not stimulate gallbladder prostanoid release in the control or BDL groups. These data show that bradykinin and not CCK stimulated PGI2 and PGE2 release from inflamed rabbit gallbladder. Increased BDL gallbladder PGI2 release may be prolonged or augmented by bradykinin as gallbladder distention and progressive acute inflammation stimulate local bradykinin formation.

Acute Disease↗