scholarly journals Distribution of prostaglandins in rabbit kidney

1970 ◽  
Vol 116 (3) ◽  
pp. 421-424 ◽  
Author(s):  
Keith Crowshaw ◽  
J. Z. Szlyk
Keyword(s):  
Fatty Acids ◽  
Arachidonic Acid ◽  
Sodium Hydroxide ◽  
Silicic Acid ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Kidney Medulla ◽  
Silicic Acid Chromatography ◽  
Before And After ◽  
Weak Activity

Three prostaglandins (PGE2, PGF2α and PGA2) are present in rabbit kidney medulla. An acidic lipid extract (0.165g) obtained from 2kg of frozen rabbit kidney cortex was separated by silicic acid chromatography to yield eluates containing fatty acids, possible non-polar prostaglandin metabolites, PGA, PGE and PGF compounds. Ultraviolet spectra of the eluates before and after treatment with sodium hydroxide did not yield chromophores typical of any known prostaglandins or related metabolites. By using more sensitive bioassay procedures (contraction of rabbit duodenum) weak activity equivalent to 60μg of PGE2 and 10μg of PGF2α was detected in the PGE and PGF eluates respectively. Extraction and bioassay of fresh kidney cortex revealed no prostaglandin-like activity. Attempts to biosynthesize prostaglandins in fresh homogenates of rabbit kidney cortex from endogenous precursors and from added arachidonic acid were unsuccessful. When freshly prepared homogenates of rabbit kidney cortex were incubated with added PGE1 no evidence of enzymic breakdown was obtained. It is concluded that rabbit kidney prostaglandins are present predominantly in the medulla and there are no cortical mechanisms for their biosynthesis or inactivation under normal conditions.

Metabolism of C14-labeled substrates by rabbit kidney cortex and medulla

1962 ◽  
Vol 203 (1) ◽  
pp. 27-36 ◽  
Author(s):  
James B. Lee ◽  
Vernon K. Vance ◽  
George F. Cahill
Keyword(s):  
Fatty Acids ◽  
The Other ◽  
High Rate ◽  
Rabbit Kidney ◽  
Kidney Cortex ◽  
Anaerobic Conditions ◽  
Kidney Medulla ◽  
Bicarbonate Buffer ◽  
Radioactive Substrate

Slices of rabbit kidney cortex and medulla were incubated for 90 min at 38 C in Krebs-Ringer bicarbonate buffer containing C14 labeled substrate. In addition to substrate disappearance and concentrations of glycogen and fatty acids, measurements were made of the amount of radioactive substrate incorporated into CO2, glycogen, and fatty acids per gram of wet tissue. Glucose, fructose, mannose, glycerol, pyruvate, and palmitate were oxidized to a significantly greater extent by cortex than medulla. The concentration of glycogen in kidney medulla was twice that of cortex and was maintained at initial concentrations only in the presence of glucose, which showed a significantly greater incorporation into medullary glycogen than did the other substrates. Under pure anaerobic conditions simulating those in vivo, the present study suggests that the metabolism of medulla is almost exclusively glucose-dependent anaerobic glycolysis. On the other hand, the cortex is capable of utilizing a variety of substrates for a high rate of aerobic metabolism.

scholarly journals Stimulation of prostaglandin E2 synthesis by exogenous phospholipase A2 and C in rabbit kidney medulla slices

1984 ◽  
Vol 218 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Y Fujimoto ◽  
N Akamatsu ◽  
A Hattori ◽  
T Fujita
Keyword(s):  
Fatty Acids ◽  
Prostaglandin E2 ◽  
Phospholipase A2 ◽  
Phospholipase C ◽  
Unsaturated Fatty Acids ◽  
Rabbit Kidney ◽  
Dependent Manner ◽  
Kidney Medulla ◽  
Diacylglycerol Lipase ◽  
Dose Dependent

We have investigated the effects of phospholipase A2 and C on the synthesis of prostaglandin E2 in rabbit kidney medulla and the release of fatty acids from the medulla slices. Exogenous phospholipase A2 [from Naja naja (Indian cobra) venom] and phospholipase C (from Clostridium welchii) stimulated prostaglandin E2 production in a dose-dependent manner. At the maximal effective concentrations (0.5 unit of phospholipase A2/ml, 2 units of phospholipase C/ml), phospholipase C increased prostaglandin E2 formation to the level observed with phospholipase A2. Phospholipase A2 enhanced the release only of unsaturated fatty acids, whereas phospholipase C stimulated the release of individual free fatty acids (C 16:0, C 18:0, C 18:1, C 18:2 and C 20:4). Moreover, p-bromophenacyl bromide inhibited phospholipase A2-stimulated prostaglandin E2 production and the release of fatty acids, but it had no influence on prostaglandin E2 formation and the release of fatty acids increased by phospholipase C, indicating that the stimulatory effect of phospholipase C is not mediated through the activation of endogenous phospholipase A2. These results suggest the presence of diacylglycerol lipase and monoacylglycerol lipase in the kidney and the importance of this pathway in prostaglandin synthesis by the kidney.

scholarly journals Prostaglandin biosynthesis and lipolysis in subcellular fractions from rabbit kidney medulla

1981 ◽  
Vol 194 (3) ◽  
pp. 957-961 ◽  
Author(s):  
A Erman ◽  
A Raz
Keyword(s):  
Arachidonic Acid ◽  
Linoleic Acid ◽  
Prostaglandin E2 ◽  
Phospholipase A2 ◽  
Plasma Membranes ◽  
Subcellular Fractions ◽  
Rabbit Kidney ◽  
Concomitant Increase ◽  
Kidney Medulla ◽  
Prostaglandin Biosynthesis

Three separate prostaglandin-generating activities are associated with plasma membranes, mitochondria and microsomal fractions from rabbit kidney medulla. In the plasma membranes and mitochondria, but not in microsomal fractions, Ca2+ ions stimulate the activity of phospholipase A2, yielding selective release of arachidonic acid and linoleic acid and concomitant increase in prostaglandin E2 formation.

scholarly journals The interaction between lipid peroxidation and prostaglandin synthesis in rabbit kidney-medulla slices

1983 ◽  
Vol 212 (1) ◽  
pp. 167-171 ◽  
Author(s):  
Y Fujimoto ◽  
H Tanioka ◽  
I Keshi ◽  
T Fujita
Keyword(s):  
Lipid Peroxidation ◽  
Ascorbic Acid ◽  
Arachidonic Acid ◽  
Prostaglandin E2 ◽  
Inhibitory Effect ◽  
Prostaglandin Synthesis ◽  
Rabbit Kidney ◽  
Kidney Medulla ◽  
Prostaglandin Endoperoxide Synthase ◽  
Generating System

Lipid peroxidation induced by ascorbic acid and Fe2+ was inhibited by mepacrine (phospholipase A2 inhibitor) and aspirin (prostaglandin cyclo-oxygenase inhibitor) in rabbit kidney-medulla slices. Moreover, ascorbic acid and Fe2+ potentiated the inhibitory effect on prostaglandin E2 formation by mepacrine, but they had no influence on prostaglandin E2 production decreased by aspirin. Lipid peroxidation induced by ascorbic acid and Fe2+ appears to be affecting the activity of prostaglandin endoperoxide synthase. These results suggest that lipid peroxidation is connected closely with the prostaglandin-generating system, and it has the potential to modulate the turnover of arachidonic acid and prostaglandin synthesis.

scholarly journals Effects of bivalent cations on prostaglandin biosynthesis and phospholipase A2 activation in rabbit kidney medulla slices

1979 ◽  
Vol 182 (3) ◽  
pp. 821-825 ◽  
Author(s):  
A Erman ◽  
A Raz
Keyword(s):  
Arachidonic Acid ◽  
Linoleic Acid ◽  
Prostaglandin E2 ◽  
Phospholipase A2 ◽  
Inhibitory Effect ◽  
Rabbit Kidney ◽  
Dependent Manner ◽  
Kidney Medulla ◽  
Bivalent Cations ◽  
Tissue Lipids

The bivalent cations Ca2+, Mg2+, Co2+, Mn2+, Sr2+ and Ba2+ were compared for their stimulatory or inhibitory effect on prostaglandin formation in rabbit kidney medulla slices. Ca2+, Mn2+ and Sr2+ ions stimulated prostaglandin generation up to 3–5-fold in a time- and dose-dependent manner (Ca2+ greater than Mn2+ congruent to Sr2+). The stimulation by Mn2+ (but not by Sr2+) was also observed in incubations of medulla slices in the presence of Ca2+. Mg2+ and Co2+ ions were without significant effects on either basal or Ca2+-stimulated prostaglandin synthesis. The stimulatory effects of Ca2+, Mn2+ and Sr2+ on medullary generation of prostaglandin E2 were found to correlate with their stimulatory effects on the release of arachidonic acid and linoleic acid from tissue lipids. The release of other fatty acids was unaffected, except for a small increase in oleic acid release. As both arachidonic acid and linoleic acid are predominantly found in the 2-position of the glycerol moiety of phospholipids, the stimulation by these cations of prostaglandin E2 formation appears to be mediated via stimulation of phospholipase A2 activity.

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