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At least 685 records · Page 38Linked to original sources
PubMed1986

Quantitative determination of propranolol in plasma and plasma water from normal subjects and patients with angina pectoris by high-performance liquid chromatography.

A precise and sensitive high-performance liquid chromatographic method using a column packed with porous polystyrene gel is described for the determination of propranolol in plasma and plasma water from normal subjects and patients with angina pectoris. Propranolol in the samples was extracted with an n-heptane-isoamylalcohol (98.5:1.5) mixture after addition of penbutolol used as an internal standard. The extracts were chromatographed and detected with a spectrofluorophotometer. The quantitative limit of propranolol was 1 ng using 1 ml of plasma or 0.5 ml of plasma water. The present method should be useful for monitoring propranolol concentrations in plasma and plasma water during drug therapy and for pharmacokinetic study of propranolol.

Angina Pectoris↗
PubMed2001

Determination of Cremophor EL in plasma after sample preparation with solid phase extraction and plasma protein precipitation.

The non-ionic emulsifier Cremophor EL can be quantified using a special potentiometric titration technique with barium chloride activation and precipitation with sodium tetraphenylborate. The end point of the titration is indicated by an ionsensitive coated wire electrode which responds to an excess of tetraphenylborate ions. Sample preparation is necessary to quantify the excipient in plasma of patients receiving ciclosporin formulations with Cremophor EL (Sandimmun), since plasma proteins cause disturbances of the titration. Solid phase extraction was tested with various sorbent materials. Although some of the sorbents yielded good extraction rates of Cremophor EL from aqueous solutions, the extraction rates from plasma were significantly lower. Therefore, plasma protein precipitation with acetonitrile has been examined as an alternative to SPE and has been proved the superior method. Using the precipitation technique, a recovery rate of above 90% was achieved. Furthermore, the limit of detection from plasma was found to be 30 microg, in analogy to the determination from aqueous solutions. The combination of the plasma protein precipitation with the potentiometric titration allows quantitation and thus pharmakokinetic investigations of Cremophor EL in patients treated with Sandimmun after kidney-transplantation.

Animals↗
PubMed1998

Monitoring of phenytoin in human breast milk, maternal plasma and cord blood plasma by solid-phase extraction and liquid chromatography.

A rapid liquid chromatographic method for the quantitation of phenytoin in human breast milk, maternal plasma and cord blood plasma was developed using a Develosil C85 micron reverse phase column and a potassium dihydrogen phosphate buffer/acetonitrile mobile phase. Phenytoin and mephenytoin as an internal standard were detected by ultraviolet absorbance at 240 nm. The sample preparation method involves a rapid and simple procedure based on solid-phase extraction using a C18-bonded phase. Phenytoin could be determined in the concentration range of 0.05-3 micrograms ml-1. The recovery of phenytoin added to human breast milk and plasma were 91.6-94.7 and 91.6-96.0%, respectively, with coefficient of variation less than 4.2 and 8.7%. The method has been used for drug level monitoring in the human breast milk, maternal plasma and cord blood plasma samples that were taken from patients treated with phenytoin. The average ratio between the breast milk concentrations versus the plasma concentration was 0.28 +/- 0.1, with a rather poor correlation (r = 0.3033).

Adult↗
PubMed2001

Plasma levels of soluble cellular adhesion molecules in patients with arterial hypertension. Correlations with plasma endothelin-1.

Background: Several reports have shown that circulating, soluble cellular adhesion molecules and endothelin-1 (ET-1) are implicated in the pathophysiological events of atherosclerosis and may reflect the endothelial dysfunction characterizing this disorder. Methods: To evaluate the expression of these factors in arterial hypertension (AH), we measured plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble P-selectin (sP-selectin), and ET-1 in 60 untreated patients with mild to moderate AH (hypercholesterolemic: n=31, normocholesterolemic: n=29) and 30 sex- and age-matched normocholesterolemic normotensive controls. Results: Hypertensive patients exhibited significantly higher levels of sICAM-1 (234+/-21 vs. 187+/-12 ng/ml, P<0.005), sVCAM-1 (681+/-42 vs. 589+/-23 ng/ml, P<0.005), sP-selectin (89+/-17 vs. 55+/-11 ng/ml, P<0.01) and ET-1 (6.2+/-0.7 vs. 2.4+/-0.3 pg/ml, P<0.01) than did normotensive controls. The normocholesterolemic hypertensives had lower levels of sICAM-1, sVCAM-1 (P<0.01), sP-selectin and ET-1 (P<0.05) than hypercholesterolemic hypertensives, but higher levels than normotensive controls (P<0.05). In hypertensives, plasma ET-1 was significantly correlated with mean arterial pressure (r=0.51, P<0.03) and sICAM-1 levels (r=0.64, P<0.01). In hypercholesterolemic hypertensives, LDL cholesterol was also significantly correlated with plasma levels of sICAM-1 (r=0.53, P<0.04) and sP-selectin (r=0.41, P<0.05). Conclusions: Plasma levels of soluble cellular adhesion molecules are elevated in hypertensive patients in comparison to normotensive controls and may be related to plasma ET-1 activity. The coexistence of hypercholesterolemia may enhance the plasma soluble adhesion molecule activity induced by AH.

Journal Article↗
PubMed2000

Binding of porcine sperm plasma membrane proteins to sheep, hamster and mouse oocyte plasma membrane.

Four porcine sperm plasma membrane proteins were previously identified as putative ligands for the oocyte plasma membrane. The present study examined the binding of these proteins and two additional porcine sperm membrane proteins to oocytes from sheep, mice and hamsters as a first step in assessing potential conservation of these putative sperm ligands across species and across mammalian orders. Plasma membrane vesicles were isolated from porcine sperm, solubilised, and the proteins separated by one-dimensional gel electrophoresis. The 7, 27, 39 and 62 kDa porcine sperm protein bands demonstrating predominant binding of the porcine oocyte plasma membrane on ligand blots, a 90 kDa protein band demonstrating minor binding, and a 97 kDa protein band that did not bind the oocyte plasma membrane probe were electroeluted. Proteins were biotinylated, and incubated with zona-free oocytes. Bound biotinylated protein was labelled with fluorescent avidin and the oocytes examined with a confocal microscope. The 7 kDa, 27 kDa and the 39 kDa proteins bound to the sheep oocytes but not to a majority of the hamster or mouse oocytes. The 62 kDa protein bound to sheep oocytes and mouse oocytes but not to a majority of the hamster oocytes. The 90 kDa protein bound to oocytes from all three species. The 97 kDa protein, which did not recognise the porcine oocyte probe on a Western ligand blot, did not bind to oocytes from any species and served as a negative control. These observations are consistent with significant conservation of molecule and function among species within the same mammalian order. Hence, one species may be a good model for other species from the same order. Only limited conservation of binding activity of porcine sperm plasma membrane proteins to rodent oocytes was observed, suggesting a greater divergence either in molecular structure or in function among species from different orders.

Animals↗
PubMed2004

Modification of aliphatic self-assembled monolayers by free-radical-dominant plasma: the role of the plasma composition.

Modification of octadecanethiolate self-assembled monolayers on Au by nitrogen-oxygen or argon-oxygen downstream microwave plasma with a low oxygen content (estimated below several percent) has been studied by synchrotron-based high-resolution X-ray photoelectron spectroscopy and water contact angle measurements. For both types of plasma, the primary processes were found to be the loss of conformational and orientational order and the oxidation of the alkyl matrix and headgroup-substrate interface. At the same time, the film modification occurred much faster and with different intermediates for the nitrogen plasma than for the argon plasma. The reasons for these differences are considered in terms of the different reactivities and different efficiencies of the energy transfer between the plasma constituents in these two types of plasma.

Journal Article↗
PubMed2004

Influence of plasma total antioxidant ability on lipid and protein oxidation products in plasma and erythrocyte ghost obtained from developing and adult rats pretreated with two vitamin K formulations.

Ferric reducing ability of plasma (FRAP), as an index of total antioxidant capacity of plasma was found to be enhanced significantly (p < 0.05) in suckling rats pretreated either with vitamin K1 (28, 56 or 84 mg/kg/3 days) or menadione (vitamin K3) at a dose of 15 mg/kg b.w./3 days. The effect of vitamin K1 on FRAP was dose-dependent and it was inversely related to the formation of lipid peroxidation products in plasma as judged by thiobarbituric acid reacting substances (TBARS). Lack of influence of the drugs on FRAP in adults was corroborated with elevation in the levels of plasma TBARS. Possible role of FRAP on the rate of lipid peroxidation and protein oxidation (protein carbonyls) on erythrocyte membrane was also investigated following isolation of erythrocyte ghost from control and treated rats. Vitamin K1 as well as menadione failed to change the levels of protein carbonyls in erythrocyte ghost obtained from both the age groups. Analysis of major erythrocyte membrane proteins, using SDS-polyacrylamide gel electrophoresis (SDS-PAGE) substantiated these results. In spite of higher antioxidant capacity of plasma and erythrocytes obtained from young rats, the rate of lipid peroxidation in erythrocyte ghost preparation was also high in this age group (p < 0.05). These results suggest that the drug-related induction in FRAP occurs only in immature animals as a part of protective mechanism against lipid peroxidation products generated in plasma.

Administration, Oral↗
PubMed1980

Biogenesis of hepatocyte plasma-membrane domains. Incorporation of (3H)fucose into plasma-membrane and golgi-apparatus glycoproteins.

1. Rats were injected intracaudally with [3H]fucose and its rate of incorporation into the fucoproteins of serum, Golgi and plasma-membrane subfractions was followed for up tp 2h. 2. Incorporation into the Golgi dictyosome and secretory-vesicular fractions reached a maximum at 15 min or less, but most of the radioactivity was associated with classes of secretory glycoproteins. Incorporation into sinusoidal plasma-membrane fractions reached a maximum at 30 min, coinciding with the maximum release of fucoproteins into the serum. Contiguous and canalicular plasma-membrane fractions were labelled slightly later and at a lower rate and specific radioactivity. 3. Fluorography of fucoproteins separated by polyacrylamide-gel electrophoresis helped to distinguish between the major secretory and membrane-bound glycoproteins. The results show that a major biogenetic sequence is probably from Golgi dictyosomes to Golgi secretory elements to a sinusoidal plasma membrane. 4. The kinetics of incorporation make it unlikely that there is rapid and direct insertion of glycoproteins into the bile-canalicular plasma membrane. A route involving direct transfer of glycoproteins via a membrane-mediated intracellular path from the blood sinusoidal to the bile-canalicular plasma membranes is proposed.

Animals↗
PubMed1980

Determination of noradrenaline uptake, spillover to plasma and plasma concentration in patients with essential hypertension.

1. The rates of entry of noradrenaline to plasma and of removal of noradrenaline from plasma, and plasma noradrenaline concentration, were determined in normal subjects and in patients with essential hypertension. Neuronal uptake of noradrenaline was assessed from the plasma tritiated noradrenaline disappearance curve, after infusion to steady state. 2. Noradrenaline disappearance was biexponential. Rapid removal was dependent on neuronal uptake, being slowed if neuronal noradrenaline uptake was reduced, either by desipramine in normal subjects, or in patients with sympathetic nerve dysfunction (autonomic insufficiency). 3. In 10 of 41 hypertensive patients the t 1 1/2 similarly was prolonged, presumptive evidence of a defect in neuronal noradrenaline uptake. Endogenous noradrenaline escaping uptake after release, and spilling over into plasma, and plasma noradrenaline concentration, were increased in these patients. 4. Defective neuronal uptake of noradrenaline, by exposing adrenoreceptors to high local transmitter concentration, may be important in the pathogenesis of essential hypertension in some patients.

Adult↗
PubMed1981

Haemodynamics, plasma noradrenaline and plasma renin in hypertensive and normotensive teenagers.

1. Plasma noradrenaline, active and inactive plasma renin, cardiac index and total peripheral vascular resistance were studied in 41 subjects, initially aged 10-19 years, who were followed up for at least 2 years after a blood pressure reading of 140 and/or 90 mmHg or more (initial hypertensives) and in 41 normotensive control subjects selected from the same population and matched for age, sex and body-mass index. 2. The initial hypertensive subjects had a lower mean cardiac index (3.63 +/- SD 0.83 vs 4.00 +/- 0.89 litre min-1 m-2), a higher mean total peripheral resistance (26.8 +/- 5.7 vs 22.8 +/- 5.5 peripheral resistance (26.8 +/- 5.7 vs 22.8 +/- 5.5 units) and a higher mean plasma noradrenaline units) and a higher mean plasma noradrenaline concentration (336 +/- 146 vs 281 +/- 126 pg/ml) than the control subjects. 3. Mean plasma noradrenaline concentration was higher in initial hypertensive subjects with a high active renin concentration than in those with a normal renin concentration (442 +/- 70 vs 324 +/- 100 pg/ml). 4. A weight-adjusted standardized regression coefficient of 0.77 between active plasma renin concentration and left ventricular mass was found in normotensive control subjects. 5. These findings are at variance with the existence of a hyperkinetic phase in young hypertensive subjects and suggest that sympathetic overactivity may be related to early essential hypertension through increase of peripheral vascular resistance.

Adolescent↗
PubMed1981

Effect of binding to plasma proteins on the interpretation of plasma cortisol concentrations after accidental injury.

1. The binding of cortisol to plasma proteins has been studied by multiple equilibrium dialysis of plasma samples taken from 14 patients before treatment after moderate or severe accidental injury and 2-5, 6-12 and 14-25 days later. 2. The total plasma cortisol concentration was initially high, but fell by 6-12 days to stable values probably near the upper limit of normal. 3. The plasma albumin and total protein concentrations fell during the first few days after the injury, but the fall in albumin was proportionally the greater. Both were rising again at the end of the study period. The albumin concentration was positively correlated with an index of its binding to cortisol calculable from the dialysis data. 4. The concentration of corticosteroid-binding globulin (CBG) rose between weeks 1 and 2 after trauma, with no statistically significant change before or afterwards. 5. The changes in binding proteins after injury were relatively small and did not greatly alter the relationship between free and total cortisol concentrations in plasma. It is concluded that in most trauma patients changes in free cortisol, generally considered to be the active fraction in plasma, can be followed adequately by measuring the total cortisol concentration.

Adolescent↗
PubMed2003

Low plasma aldosterone despite normal plasma renin activity in uncomplicated type 1 diabetes mellitus: effects of RAAS stimulation.

BACKGROUND: Data on levels and responsiveness of PRA and aldosterone in type 1 diabetes mellitus are conflicting. Earlier studies were not standardized with respect to the type of diabetes mellitus, the presence of diabetic complications or sodium intake. Therefore, we studied plasma renin activity and plasma aldosterone in uncomplicated type 1 diabetes mellitus by evaluating the effects of endogenous (sodium restriction) and exogenous (angiotensin I infusion) stimulation. DESIGN: Twenty-four type 1 diabetic patients and 24 matched healthy subjects were studied after 1 week of liberal sodium diet (200 mmol 24 h-1) and 1 week of low sodium diet (50 mmol 24 h-1). Angiotensin (Ang)I was infused at 4 and 8 ng kg-1 min-1 during both study days. RESULTS: During liberal and low sodium intake, plasma aldosterone was lower in type 1 diabetic patients compared with healthy subjects both at 08:00 h (P < 0.05) and after a 2-h euglycaemic clamp (P < 0.05), despite similar PRA levels. The correlations between changes in PRA and changes in plasma aldosterone when shifting sodium intake were similar in both groups. During liberal sodium intake, the aldosterone levels after AngI infusion were lower in type 1 diabetic patients, whereas during low sodium they were not different. CONCLUSIONS: Plasma aldosterone was deceased relative to PRA in uncomplicated type 1 diabetic patients, irrespective sodium intake. The responsiveness to sodium restriction was adequate and sodium restriction was able to overcome the decreased plasma aldosterone response to exogenous AngI, which was observed during liberal sodium in diabetic patients. The lower aldosterone is not secondary to diabetic complications and does not depend on the level of sodium intake.

Adult↗
PubMedDate not supplied

Atenolol improves ventricular function without changing plasma noradrenaline but decreasing plasma atrial natriuretic factor in chronic heart failure.

1 There is good evidence that beta-blockers improve ventricular function, disease progression and survival in patients with left ventricular systolic dysfunction. The aim of this study was to determine the effects of atenolol therapy on the sympathetic nervous system at rest and after ergometric exercise, on left ventricular function and on baseline plasma atrial natriuretic factor (ANF) in ambulatory patients with chronic heart failure (CHF). 2 Twenty-two patients [left ventricular ejection fraction (LVEF) <36%; New York Heart Association II-III] were studied before atenolol treatment. Because of cardiac events (new Hospital admission or death) only 13 patients completed 1 year of treatment. Baseline noradrenaline (NE) concentrations were similar in patients and controls while ANF was higher in patients than in controls (328 +/- 35 pg ml(-1) vs. 37 +/- 3 pg ml(-1); P<0.01). 3 Patients with events showed higher NE (540 +/- 87 pg ml(-1) vs. 303 +/- 44 pg ml(-1); P<0.01) and ANF (460 +/- 70 pg ml(-1) vs. 291 +/- 44 pg ml(-1); P<0.03) at rest; and greater NE response to exercise (2.003 +/- 525 pg ml(-1) vs. 694 +/- 121 pg ml(-1); P<0.005). Atenolol treatment improved LVEF (19.5 +/- 1.9% vs. 33 +/- 3.9%; P<0.001), increased exercise tolerance (9 +/- 3.2 min vs. 17 +/- 4.8 min; P<0.001) and decreased plasma ANF (292 +/- 42 pg ml(-1) vs. 133 +/- 35 pg ml(-1); P<0.01). 4 Reduced basal dihydroxyphenylglycol (DHPG)/NE ratio (3.4 +/- 0.46 vs. 4.3 +/- 0.35; P<0.01) was observed in patients compared with healthy volunteers. Atenolol increased DHPG plasma levels (1.398 +/- 129 pg ml(-1) vs. 913 +/- 86 pg ml(-1); P<0.005) but the DHPG/NE ratio during exercise was not modified after treatment, suggesting that re-uptake of released NE is not changed by beta-blocker treatment. 5 In conclusion, the fact that atenolol treatment improves ventricular dysfunction and clinical status without changing plasma NE levels in CHF patients, suggests that plasma NE is a poor surrogate measurement for cardiac sympathetic activity in this pathology. In addition, decrease in plasma ANF produced by atenolol treatment may reflect the improvement of ventricular function.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

The use of pluronic polyols in the precipitation of plasma proteins and its application in the preparation of plasma derivatives.

Pluronic F-38 was used a precipitant of plasma proteins under varying conditions of pH and polymer concentration. Results indicated that marked differences in the solubility of the plasma proteins in F-38 solutions can be appled to the separation of plasma components. The feasibility of the industrial application of this fractionation method was tested in several experiments. Conditions were established for the preparation of albumin, human plasma protein fraction (HPPF), and immune serum globulin (ISG) with similar yield and purity as those prepared by the Cohn methods. Current procedures for the preparation of antihemophilic A (Facor VIII) concentrate and prothrombin complex (Factors II, VII, IX, and X) were adapted to the F-38 process by removal of the clotting factors from the starting plasma prior to polymer precipitation. In addition, a plasma protein solution free of lipoproteins, isoagglutinins, and clotting factors was developed which has proven useful as a perfusion medium in organ preservation.

Blood Preservation↗
PubMed2001

Thyroid hormone increases plasma cholesteryl ester transfer protein activity and plasma high-density lipoprotein removal rate in transgenic mice.

Thyroid dysfunction produces multiple alterations in plasma lipoprotein levels, including high-density lipoprotein (HDL). Cholesteryl ester transfer protein (CETP) and hepatic lipase (HL) are important proteins that modulate the metabolism of HDL. Thus, the effect of thyroid hormone on the activities of CETP and of HL was investigated using hypothyroid and hyperthyroid CETP transgenic (Tg) and nontransgenic (nTg) mice. Hyperthyroid Tg mice plasma lipoprotein (LP) profile analysis showed a significant increase in the very-low-density lipoprotein (VLDL) fraction (P <.001) and decrease in the HDL fraction (P <.005), whereas in the hypothyroid Tg mice an increase in low-density lipoprotein (LDL) was observed (P <.02). CETP activity was measured as the transfer of (14)C-cholesteryl ester (CE) from labeled HDL to LDL by an isotopic assay indicative of mass. Hyperthyroid Tg mice had twice as much plasma CETP activity as compared with their controls, while in hypothyroid Tg mice plasma CETP activity did not change. The role of CETP in determining the changes in LP profile of hyperthyroid animals was confirmed by showing that nTg wild-type hyperthyroid and euthyroid mice exhibited the same percent cholesterol distribution in LP. Postheparin HL activity measured in hyperthyroid Tg mice was significantly reduced (P <.05). (3)H-cholesteryl oleoyl ether ((3)H-Cet)-HDL plasma fractional removal rate (FRR) was approximately 2-fold faster in the hyperthyroid Tg mice than in controls, but was not modified in hypothyroid animals. Tissue uptake of (3)H-Cet was examined in 10 tissue samples: levels were significantly increased in skeletal muscle and decreased in small intestine in hyperthyroid Tg mice, and decreased in the small intestine of hypothyroid Tg mice. In conclusion, the excess of thyroid hormone accelerates HDL metabolism in CETP transgenic mice mainly due to an increase in plasma CETP activity and independently from the HL activity. Hypothyroid status did not change CETP activity and HDL metabolism.

Animals↗
PubMed2001

Relationship between plasma levels of cardiac natriuretic peptides and soluble Fas: plasma soluble Fas as a prognostic predictor in patients with congestive heart failure.

BACKGROUND: Cardiac natriuretic peptides may induce apoptosis in myocytes; however, the relationship between plasma levels of cardiac natriuretic peptides and those of soluble Fas (sFas) and tumor necrosis factor (TNF)-alpha remains unknown in patients with congestive heart failure (CHF). METHODS AND RESULTS: We measured plasma levels of sFas and TNF-alpha and those of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), norepinephrine, and endothelin 1 in 96 patients with CHF (ejection fraction < 45%). The patients were monitored for 3 years. Plasma levels of sFas and TNF-alpha increased with the severity of CHF. There was no significant correlation between sFas plasma levels and those of ANP and BNP. Cox proportional hazard analysis showed that high levels of sFas (P = .009) and BNP (P < .0001) and a low ejection fraction (P = .019) were independent significant prognostic predictors. CONCLUSIONS: There is no significant correlation between cardiac natriuretic peptide and sFas levels in plasma. Plasma sFas is a useful prognostic marker independent of neurohumoral factors, suggesting that immune activation and/or apoptosis play a significant role in the pathogenesis of CHF.

Age Factors↗
PubMed1994

Sex differences in dehydroepiandrosterone metabolism in the rat: different plasma levels following ingestion of DHEA-supplemented diet and different metabolite patterns in plasma, bile and urine.

Plasma dehydroepiandrosterone (DHEA) and DHEA sulfate levels were determined by an enzyme immunoassay in male and female Sprague-Dawley rats fed a diet containing 0.6% or 0.3% DHEA. A significant difference in DHEA plasma levels was observed in male and female animals. In male rats, total DHEA plasma concentrations were found in the range of 0.4-1.5 microgram/ml (0.6% DHEA chow) and 0.3-0.5 microgram/ml (0.3% DHEA chow). In female animals several times higher DHEA plasma levels were determined: 17.5-33 micrograms/ml (0.6% DHEA chow) and 8.3-14.8 micrograms/ml (0.3% DHEA chow). DHEA was present in rat plasma of both sexes preferably as the sulfate conjugate. Significant sex differences were also found in the DHEA metabolite patterns obtained by TLC separation of extracts from plasma, bile and urine following administration of 3H-DHEA. In female rats, DHEA is present predominantly as the sulfate conjugate in considerable amounts in all materials investigated, whereas in male rats polar metabolites dominate in the patterns.

Animals↗
PubMed2005

Phosphate-limited oat. The plasma membrane and the tonoplast as major targets for phospholipid-to-glycolipid replacement and stimulation of phospholipases in the plasma membrane.

We recently reported that cultivation of oat (Avena sativa L.) without phosphate resulted in plasma membrane phosphoglycerolipids being replaced to a large extent by digalactosyldiacylglycerol (DGDG) (Andersson, M. X., Stridh, M. H., Larsson, K. E., Liljenberg, C., and Sandelius, A. S. (2003) FEBS Lett. 537, 128-132). We report here that DGDG is not the only non-phosphorous-containing lipid that replaces phospholipids but that also the content of glucosylceramides and sterolglycosides increased in plasma membranes as a response to phosphate starvation. In addition, phosphate deficiency induced similar changes in lipid composition in the tonoplast. The phospholipid-to-glycolipid replacement apparently did not occur to any greater extent in endoplasmic reticulum, Golgi apparatus, or mitochondrial inner membranes. In contrast to the marked effects on lipid composition, the polypeptide patterns were largely similar between root plasma membranes from well-fertilized and phosphate-limited oat, although the latter condition induced at least four polypeptides, including a chaperone of the HSP80 or HSP90 family, a phosphate transporter, and a bacterial-type phosphoesterase. The latter polypeptide reacted with an antibody raised against a phosphate deficiency-induced phospholipase C from Arabidopsis thaliana (Nakamura, Y., Awai, K., Masuda, T., Yoshioka, Y., Takamiya, K., and Ohta, H. (2005) J. Biol. Chem. 280, 7469-7476). In plasma membranes from oat, however, a phospholipase D-type activity and a phosphatidic acid phosphatase were the dominant lipase activities induced by phosphate deficiency. Our results reflect a highly developed plasticity in the lipid composition of the plasma membrane and the tonoplast. In addition, phosphate deficiency-induced alterations in plasma membrane lipid composition may involve different sets of lipid-metabolizing enzymes in different plant tissues or species, at different stages of plant development and/or at different stages of stress adjustments.

Amino Acid Sequence↗