Search PubMed⌕ Search

Biomedical subjects

E Degerman

Publications and source records attributed to E Degerman.

59 records · Page 4Linked to original sources
PubMed1989

Relaxant effects of the selective phosphodiesterase inhibitors milrinone and OPC 3911 on isolated human mesenteric vessels.

Several new positive inotropic drugs with vasodilating properties for which a major mechanism of action is believed to be inhibition of phosphodiesterase (PDE) have been introduced in the treatment of congestive heart failure. Hydrolysis of cyclic nucleotides is catalyzed by multiple forms of PDE, which may vary between organs and cell-types. These enzymes can be selectively inhibited by various agents, theoretically making it possible to produce tissue-selective responses. An enzyme, which belongs to a subclass of cGMP inhibited low Km cAMP PDE, was recently purified from rat adipose tissue. The enzyme was specifically and potently inhibited by the cilostamide derivative OPC 3911 (OPC) and milrinone (mil). We studied the relaxant effects of OPC and mil on isolated human mesenteric arteries and veins in vitro. In preparations contracted by noradrenaline (NA), both agents produced about 60% maximum relaxation; OPC was 3-4 times more potent than mil. Both OPC and mil caused rightward displacement of the NA concentration-response curve and depressed the maximum responses. Arteries, as compared to veins, were more sensitive to this inhibition of NA contraction. Both drugs relaxed arteries contracted by 30 mM K+, but not 127 mM K+; maximum relaxation was between 60 and 70%. OPC was 10 times more potent than mil. The interactions between mil/OPC and isoprenaline, forskolin and ouabain were also studied. In preparations pretreated with isoprenaline or forskolin, the relaxant effects of mil and OPC were additive to those of isoprenaline and forskolin. Ouabain pretreatment did not affect the actions of the phosphodiesterase inhibitors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Purification, properties and polyclonal antibodies for the particulate, low Km cAMP phosphodiesterase from bovine adipose tissue.

The particulate, cGMP- and cilostamide-inhibited "low Km" cAMP phosphodiesterase was purified greater than 100,000-fold in good yield (approximately 20%) from bovine omental fat by a procedure similar to that utilized for purification of an analogous enzyme from rat epididymal adipose tissue; ten-fold more enzyme protein (20-30 micrograms) could be prepared from bovine omentum (25 kg) than from rats (approximately 900 fat pads). Kinetic parameters (all similar to those for the rat enzyme) were: for cAMP, Km and Vmax = 0.3 microM and 2.5 mumol/min/mg, respectively; for cGMP, 0.8 microM and 1.6 mumol/min/mg. For inhibition of cAMP hydrolysis, IC50 values were: for cGMP = 0.6 microM and for OPC 3911, milrinone, CI 930, 0.1-2.0 microM. The purified enzyme, the activity of which eluted from Sephadex G-200 with Mr(app) = 110,000 and was associated with a single protein band during non-denaturing electrophoresis, exhibited on SDS-PAGE silverstained bands of 62 (probably a 61-63 doublet) and 77 kDa, perhaps due to proteolytic nicking. On Western blots, each of the polypeptides cross-reacted with a monoclonal antibody toward the bovine cardiac low Km cAMP and polyclonal rabbit antibody generated toward the purified bovine omental phosphodiesterase. Rabbit anti-phosphodiesterase IgG, which inhibited bovine and rat phosphodiesterase enzymatic activity, did not cross-react with purified bovine retina cGMP-binding or bovine cGMP-stimulated phosphodiesterase.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1987

Purification of the putative hormone-sensitive cyclic AMP phosphodiesterase from rat adipose tissue using a derivative of cilostamide as a novel affinity ligand.

A "low Km" cAMP phosphodiesterase with properties of a peripheral membrane protein accounts for approximately 90% of total cAMP phosphodiesterase activity in particulate (100,000 X g) fractions from rat fat cells. Incubation of fat cells with insulin for 10 min increased particulate (but not soluble) cAMP phosphodiesterase activity, with a maximum increase (approximately 100%) at 1 nM insulin. Most of the increase in activity was retained after solubilization (with non-ionic detergent and NaBr) and partial purification (approximately 20-fold) on DEAE-Sephacel. The solubilized enzyme from adipose tissue was purified approximately 65,000-fold to apparent homogeneity (yield approximately 20%) by chromatography on DEAE-Sephacel and Sephadex G-200 and affinity chromatography on aminoethyl agarose conjugated with the N-(2-isothiocyanato)ethyl derivative of the phosphodiesterase inhibitor cilostamide (OPC 3689). A 63,800 +/- 200-Da polypeptide (accounting for greater than 90% of the protein eluted from the affinity column) was identified by polyacrylamide gel electrophoresis in sodium dodecyl sulfate (with or without reduction). Enzyme activity was associated with the single protein band after electrophoresis under nondenaturing conditions. On gel permeation, Mr(app) was 100,000-110,000, suggesting that the holoenzyme is a dimer. A pI of 4.9-5.0 was estimated by isoelectric focusing. At 30 degrees C, the purified enzyme hydrolyzed both cAMP and cGMP with normal Michaelis-Menten kinetics; the pH optimum was 7.5. The Km(app) for cAMP was 0.38 microM and Vmax, 8.5 mumol/min/mg; for cGMP, Km(app) was 0.28 microM and Vmax, 2.0 mumol/min/mg. cGMP competitively inhibited cAMP hydrolysis with a Ki of approximately 0.15 microM. The enzyme was also inhibited by several OPC derivatives and "cardiotonic" drugs, but not by RO 20-1724. It was very sensitive to inhibition by agents which covalently modify protein sulfhydryls, but not by diisopropyl fluorophosphate. The activation by insulin and other findings indicate that the purified enzyme, which seems to belong to a subtype of low Km cAMP phosphodiesterases that is specifically and potently inhibited by cGMP, cilostamide, other OPC derivatives, and certain cardiotonic drugs, is likely to account for the hormone-sensitive particulate low Km cAMP phosphodiesterase activity of rat adipocytes.

3',5'-Cyclic-AMP Phosphodiesterases↗