In situ microdialysis of prostaglandins in adipose tissue: stimulation of prostacyclin release by angiotensin II.
In order to clarify the physiological roles that PGE2 and PGI2, the two major metabolites of arachidonic acid in adipose tissue could play in vivo, their measurements have been undertaken in the interstitial fluid of rat periepididymal adipose tissue using in situ microdialysis. This technique appears suitable with a rather high dialysis yield (70%) for the measurement of prostaglandins. The basal equilibrium extracellular concentrations of 6-keto-PGF1 alpha (the stable metabolite of PGI2) and PGE2 can be estimated to 1 and 0.3 nM, respectively. Experiments designed to study the hormonal regulation of in situ PGI2 and PGE2 production show that (i) lipolysis induced by local perfusion of 10(-6) M isoproterenol is not accompanied by an increase of either 6-keto-PGF1 alpha or PGE2 in the dialysate but, in contrast (ii) perfusion of angiotensin II (10(-7)-10(-5) M) leads, independently of triacylglycerol hydrolysis, to a transient dose-dependent and indomethacin-sensitive increase of released 6-keto-PGF1 alpha with no change in released PGE2. Therefore, in vivo PGI2 appears as the major hormonally regulated prostaglandin in rat adipose tissue, and angiotensin II appears as a physiological effector of its extracellular release.
Darimont
C
C
Centre de Biochimie (UMR 134 CNRS) Université de Nice Sophia-Antipolis, Faculté des Sciences, Nice, France.
Vassaux
G
G
Gaillard
D
D
Ailhaud
G
G
Négrel
R
R
D000273:Adipose Tissue / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism*; D000804:Angiotensin II / Q000494:pharmacology* / Q000502:physiology; D000818:Animals; D002138:Calibration; D015232:Dinoprostone / Q000032:analysis / Q000378:metabolism / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D011464:Epoprostenol / Q000032:analysis / Q000378:metabolism* / Q000502:physiology; D007213:Indomethacin / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D017551:Microdialysis; D011453:Prostaglandins / Q000032:analysis* / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D014280:Triglycerides / Q000378:metabolism
D011453:Prostaglandins; D014280:Triglycerides; D000804:Angiotensin II; D011464:Epoprostenol; D015232:Dinoprostone; D007545:Isoproterenol; D007213:Indomethacin