The identification of prostaglandins E2, F2α and A2 from rabbit kidney medulla

Abstract

Rabbit kidney medulla (10kg.) was homogenized in 5mm-disodium hydrogen phosphate and deproteinized with ethanol, and the concentrated supernatant solution was extracted at pH8 with light petroleum and at pH2 with chloroform. The acidic lipids present in the chloroform phase were separated on silicic acid columns into three biologically active fractions. The first fraction contained only vasodepressor activity; the second fraction contained both vasodepressor and non-vascular-smooth-muscle-stimulating activity; the third fraction contained both vasopressor and non-vascular-smooth-muscle-stimulating activity. Purification of each fraction by reversed-phase partition and thick-layer chromatography yielded three pure acids. Thin-layer chromatographic, spectroscopic and mass-spectral analysis of the acids and their methyl esters established their structures as prostaglandins E(2), F(2alpha) and A(2). Evidence is presented demonstrating that part or all of the prostaglandin A(2) is formed during the isolation procedures from endogenous prostaglandin E(2).

Inhibition of sodium transport by prostaglandin E2 across the isolated, perfused rabbit collecting tubule.

“…Since PGE2 is found in high concentrations in the medulla (4), the response of the PD in the MCT was also examined. This segment is morphologically indistinguishable from the CCT at x400 during the experiment.…”

Evidence for Prostaglandin Mediated Prejunctional Control of Renal Sympathetic Transmitter Release and Vascular Tone

“…Prostaglandin E2 is the most abundant renal prostaglandin and is a potent vasodilator (Lee, Crowshaw, Takman, Attrep & Gougoutas, 1967;Daniels, Hinman, Leach & Muirhead, 1967). Consequently, it has been postulated that this prostaglandin has a physiological role in blood flow regulation in the kidney (McGiff, Crowshaw, Terragno & Lonigro, 1970;Lonigro, Terragno, Malik & McGiff, 1973;McGiff & Itskovitz, 1973;Herbaczynska-Cedro & Vane, 1973Larsson & Anggard, 1974;Needleman, Douglas, Jalsetik, Stoecklein & Johnson, 1974).…”

Medullopressin: A New Pressor Activity from the Renal Medulla

“…The methylene chloride phase was then extracted by shaking with phosphate buffer, the idea being that only the acid lipids would pass into the buffer, while the neutral lipids would remain behind. The phosphate buffer was then acidified and extracted again with methylene chloride; the organic phase now contained the activity, which later led to the discovery of the prostaglandins in the kidney (26). However, the original methylene chloride extract contained an activity that was later described by Muirhead (22) as the ANRL activity mentioned above.…”

“…Moreover, the method of lipid extraction that has been employed to isolate the prostaglandins from the renal medulla has to be considered in the discussion of potential candidates for the active principle (26). As Lee explained (47), the purpose of the extraction method is the exclusion of the neutral lipids, the preservation of the acidic prostaglandins, and their separation from the neutral lipids.…”