ABSTRACT
Gills and opercular epithelia of the killifish (Fundulus heteroclitus) homogenized and incubated with radiolabeled arachidonic acid were found to produce prostaglandins, leukotrienes, and hydroxyeicosatetraenoic acids. These metabolites were identified using thin-layer chromatography, autoradiography, reverse-phase high-performance liquid chromatography, and ultraviolet spectroscopy. Addition of glutathione and epinephrine to the incubation mixture caused a diminution in the production of most eicosanoids (cyclooxygenase and lipoxygenase products) whereas indomethacin decreased only the cyclooxygenase metabolites. The effects of eicosanoids on short-circuit and potential difference across opercular epithelia mounted in a Ussing-type chamber were examined. Prostaglandin E2 had an inhibitory effect on ion transport whereas the sulfidopeptide leukotrienes (LTC4, LTD4, and LTE4) had a stimulatory effect. These results indicate that gills and opercular epithelia have the capacity to synthesize eicosanoids and that some of these metabolites may play a role in the regulation of ion transport in the kill fish.
Subject(s)
Arachidonic Acids/metabolism , Cyprinodontiformes/metabolism , Gills/metabolism , Killifishes/metabolism , Prostaglandins/biosynthesis , SRS-A/biosynthesis , Animals , Arachidonic Acid , Arachidonic Acids/pharmacology , Biological Transport, Active/drug effects , Epithelium/drug effects , Epithelium/metabolism , Female , Lipoxygenase/metabolism , Male , Prostaglandin-Endoperoxide Synthases/metabolism , Prostaglandins/pharmacology , SRS-A/pharmacologyABSTRACT
Leukotrienes (LT) have been proposed to be important mediators in the etiology of the acute asthma attack (AAA). We therefore studied blood LT levels in 18 children having AAA. Heparinized blood samples were obtained before and after treatment with epinephrine injections and/or metaproterenol inhalations in the emergency room. The samples were acidified and subjected to Sep-pak chromatography. Reverse phase high performance liquid chromatography (RP-HPLC), ultraviolet (UV) spectroscopy and bioassay on guinea pig ileum were used to identify the LT based on comparison to data produced by standard synthetic LT samples. Radioimmunoassay (RIA) was used to further confirm the presence of LT. LT C, D and E were detected in the plasma of children having AAA. Only LT C levels were significantly elevated over control values. The mean blood LT C level of control patients was 1.6 +/- 1.2 nanograms per milliliter (ng/ml, mean +/- SEM) while that of the asthma patients was 73.8 +/- 18.2 ng/ml prior to treatment. After emergency room treatment the asthma patients had a mean blood LT C level of 22.5 +/- 11.7 ng/ml. Lowered levels of LT C accompanied improved clinical condition of the patients. This finding indicates that the AAA in children is associated with elevated blood levels of LT C.
Subject(s)
Asthma/blood , SRS-A/blood , Adolescent , Asthma/drug therapy , Child , Child, Preschool , Epinephrine/therapeutic use , Female , Humans , Leukotriene E4 , Male , Metaproterenol/therapeutic use , SRS-A/analogs & derivativesABSTRACT
The influence of the oral administration of prazosin (an alpha 1-adrenergic blocker) and propranolol (a beta-adrenergic blocker) on eicosanoid formation in renal cortices and papillae was evaluated in rabbits maintained on a high cholesterol diet. Rabbit renal microsomal fractions were incubated with radiolabeled arachidonic acid (AA) and glutathione (GSH) and the levels of metabolites were determined by thin layer chromatography (TLC), autoradiography and reverse phase-high performance liquid chromatography (RP-HPLC). Rabbits on a high cholesterol diet showed no significant differences in total eicosanoid production compared to rabbits on a normal diet. Prazosin was found to significantly inhibit the formation of all eicosanoids in the renal cortex. In contrast, propranolol had no such inhibitory effect in the renal cortex. Neither drug had a significant effect on eicosanoid formation in the renal papilla. While oral administration of prazosin effectively inhibited the formation of all eicosanoids in the cortex, the addition of prazosin in vitro at physiological concentrations showed no such effect. These findings may have reflected alpha-receptor mediated event(s) which resulted in an alteration in eicosanoid formation in the kidney, suggesting an interaction between the sympathetic nervous system and the AA cascade.
Subject(s)
Arachidonic Acids/metabolism , Kidney Cortex/drug effects , Prazosin/pharmacology , Animals , Arachidonic Acid , Cholesterol/blood , Cholesterol, Dietary/administration & dosage , In Vitro Techniques , Kidney Cortex/metabolism , Kidney Medulla/drug effects , Kidney Medulla/metabolism , Microsomes/metabolism , Propranolol/pharmacology , RabbitsABSTRACT
Production of radiolabeled arachidonic acid (AA) metabolites by microsomal fractions obtained from rabbit renal papillae and cortices was investigated. It was determined that in addition to the cyclooxygenase products synthesized, the papillary fractions and the cortical fractions each produced 5-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE), 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) and three leukotrienes (LT). The LT of greatest polarity showed an ultraviolet (UV) spectrum of a conjugated triene chromophore and coeluted with standard LT C4 on reverse phase high performance liquid chromatography (RP-HPLC). Amino acid analysis revealed the presence of a glutathionyl moiety, whereas mass spectrometric analysis of the trimethylsilyl ether and methyl ester derivative of this LT indicated the lipid portion to be 5-hydroxy-arachidic acid. In addition, this LT was found to contract guinea pig ileum. The other LTs were found to lack bioactivity on guinea pig ileum but contained a glutathionyl moiety. These findings indicate that rabbit renal microsomes possess lipoxygenase activity capable of producing hydroxy acids, such as 5-HETE, 12-HETE and LT.
