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PubMed1988

Possible activation of intracellular beta-adrenoceptors by extraneuronally accumulated isoprenaline in perfused rat heart.

Two rat hearts were perfused in series by a modified Loewi's method. The recipient heart was perfused with the perfusate collected from the donor heart. 1. After perfusion with 3H-isoprenaline in the presence of tropolone, an inhibitor of catechol-O-methyltransferase, the donor heart was washed out with amine-free medium containing tropolone and corticosterone. The heart rate of the recipient heart increased after the change to the perfusate from the donor heart during the wash-out. After wash-out the heart rate of the donor heart (which had accumulated 43.4 pmol.g-1 3H-isoprenaline) was higher than that of the recipient heart (which had accumulated 0.44 pmol.g-1 3H-isoprenaline), and the rates of efflux of 3H-isoprenaline from both hearts were similar. 2. After perfusion with 3H-isoprenaline and corticosterone in the absence of tropolone, the enhanced heart rate of the donor heart decreased during wash-out with amine-free medium in the presence of corticosterone. The heart rate of the recipient heart increased after the medium change to the perfusate from the donor heart, and the heart rates in both hearts were similar after wash-out. Only small amounts of 3H-isoprenaline remained in both hearts after wash-out, and the rates of efflux of 3H-isoprenaline from both hearts were similar. 3. After perfusion with 3H-isoprenaline in the presence of tropolone, the effects of propranolol and atenolol on the heart rate during wash-out with amine-free medium containing tropolone and corticosterone were compared. The inhibitory effect of propranolol on the heart rate was significantly greater than that of atenolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

On the recovery of [3H]noradrenaline from different metabolic compartments of rat brain with respect to the role of catechol-O-methyltransferase.

Rats were treated with reserpine, desmethyl-imipramine, or carrier, either alone or in combination with tropolone. Either 10 min (t1) or 1 h (t2) after intraventricular injection of [3H]noradrenaline, they were decapitated. The total 3H activity and the recovery of [3H]noradrenaline were determined in tissue extracts from various brain regions. Maximum total 3H activity was measured at t1 in all tropolone-treated rats; the mean sum of these results served as an estimate of the initial tissue concentration of [3H]noradrenaline. At t1, 40-50% of the sum of [3H]noradrenaline and its metabolites was recovered unchanged in normal rats; reserpine and DMI reduced the recovery to 18-27%. In all groups, the decline of [3H]noradrenaline was retarded after t1. Inhibition of catechol-O-methyltransferase by tropolone caused consistently elevated [3H]noradrenaline levels, but did not affect the metabolic rate after t1 when compared with similarly pretreated, but tropolone-free rats. Thus, if catechol-O-methyltransferase was inhibited during the injection of [3H]noradrenaline, a higher percentage of the amine had been taken up into spaces with a slow noradrenaline turnover. The maximum increase was seen when the neuronal uptake1 was inhibited by desmethylimipramine. This supported the hypothesis that an additional extraneuronal space exists, in addition to the known intraneuronal and extraneuronal compartments, which has a slow noradrenaline turnover. The tropolone effect on the noradrenaline recovery possibly shows that there might be a saturable "methylating system," similar to that described for the periphery, in which catechol-O-methyltransferase is linked to the extraneuronal uptake2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Comparison of several indium-111 ligands in labeling blood cells: effect of diethylpyrocarbonate and CO2.

The effect of oxine sulfate, oxine sulfonate, tropolone, and Merc (2 mercaptopyridine-1-oxide) were compared with oxine, with respect to their capability of labeling blood cells when complexed to indium-111 (111In). Indium-111 oxine sulfate performed similarly to [111In]oxine with regard to cell labeling capability. Indium-111 oxine sulfonate had no labeling ability. Indium-111 tropolone and Merc were not superior to [111In]oxine as cell labeling agents. Carbon dioxide (CO2) and a CO2 generating compound, diethyl pyrocarbonate, dramatically improved the cell labeling ability in plasma of [111In]tropolone and Merc. In the case of oxine, this improvement was less distinct. Theoretical aspects of the CO2 cell labeling stimulating effect are discussed in terms of intra- and extracellular transferrin and lactoferrin iron (indium) binding capacity. Indium-111 tropolone behaved favorably with respect to inhibition of leukocyte migration, compared with oxine and Merc. Combined with the property of easy cell labeling and good solubility in water, also in the complexed state, tropolone must be regarded as the most suitable cell labeling ligand.

Animals↗
PubMed1982

Interaction of tubulin with single ring analogues of colchicine.

Simple analogues of the tropolone and trimethoxyphenyl moieties of colchicine have been used as probes for the colchicine binding site of purified calf brain tubulin. [3H]Tropolone methyl ether was found to bind to one site per tubulin molecule with equilibrium constant of (2.2 +/- 0.2) x 10(3) M-1 at 0 degree C, with the interaction having delta H0app = -8.3 +/- 1.0 kcal mol-1 and delta S0app = -15.2 +/- 3.6 eu. The binding of tropolone methyl ether and colchicine was inhibited by each other. Both tropolone and its methyl ether inhibited tubulin polymerization into microtubules in vitro. N-[3H]Acetylmescaline bound to tubulin with a K congruent to 4 x 10(2) M-1 at 37 degrees C. This interaction was inhibited by colchicine and at lower temperatures was below the sensitivity of the measuring method employed. [14C]Mescaline interacted with higher affinity site(s) not related to the colchicine site. Both mescaline and N-acetylmescaline inhibited partially the microtubule assembly at 10(-3) M concentrations. No linkage was observed between the binding of tropolone methyl ether and N-acetylmescaline. The relatively weak interactions of both the two separate parts of colchicine can account quantitatively for the much tighter binding of the complete drug to tubulin within a proposed model which takes into account the entropic advantage of colchicine as a bifunctional ligand.

Colchicine↗
PubMed2005

Characterization and purification of polyphenol oxidase from artichoke (Cynara scolymus L.).

In this study, the polyphenol oxidase (PPO) of artichoke (Cynara scolymus L.) was first purified by a combination of (NH(4))(2)SO(4) precipitation, dialysis, and a Sepharose 4B-L-tyrosine-p-aminobenzoic acid affinity column. At the end of purification, 43-fold purification was achieved. The purified enzyme migrated as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Polyacrylamide gel electrophoresis indicated that PPO had a 57 kDa molecular mass. Second, the contents of total phenolic and protein of artichoke head extracts were determined. The total phenolic content of artichoke head was determined spectrophotometrically according to the Folin-Ciocalteu procedure and was found to be 425 mg 100 g(-1) on a fresh weight basis. Protein content was determined according to Bradford method. Third, the effects of substrate specificity, pH, temperature, and heat inactivation were investigated on the activity of PPO purified from artichoke. The enzyme showed activity to 4-methylcatechol, pyrogallol, catechol, and L-dopa. No activity was detected toward L-tyrosine, resorsinol, and p-cresol. According to V(max)/K(m) values, 4-methylcatechol (1393 EU min(-1) mM(-1)) was the best substrate, followed by pyrogallol (1220 EU min(-1) mM(-1)), catechol (697 EU min(-1) mM(-1)), and L-dopa (102 EU min(-1) mM(-1)). The optimum pH values for PPO were 5.0, 8.0, and 7.0 using 4-methylcatechol, pyrogallol, and catechol as substrate, respectively. It was found that optimum temperatures were dependent on the substrates studied. The enzyme activity decreased due to heat denaturation of the enzyme with increasing temperature and inactivation time for 4-methylcatechol and pyrogallol substrates. However, all inactivation experiments for catechol showed that the activity of artichoke PPO increased with mild heating, reached a maximum, and then decreased with time. Finally, inhibition of artichoke PPO was investigated with inhibitors such as L-cysteine, EDTA, ascorbic acid, gallic acid, d,L-dithiothreitol, tropolone, glutathione, sodium azide, benzoic acid, salicylic acid, and 4-aminobenzoic acid using 4-methylcatechol, pyrogallol, and catechol as substrate. The presence of EDTA, 4-aminobenzoic acid, salicylic acid, gallic acid, and benzoic acid did not cause the inhibition of artichoke PPO. A competitive-type inhibition was obtained with sodium azide, L-cysteine, and d,L-dithiothreitol inhibitors using 4-methylcatechol as substrate; with L-cysteine, tropolone, d,L-dithiothreitol, ascorbic acid, and sodium azide inhibitors using pyrogallol as substrate; and with L-cysteine, tropolone, d,L-dithiotreitol, and ascorbic acid inhibitors using catechol as a substrate. A mixed-type inhibition was obtained with glutathione inhibitor using 4-methylcatechol as a substrate. A noncompetitive inhibition was obtained with tropolone and ascorbic acid inhibitors using 4-methylcatechol as substrate, with glutathione inhibitor using pyrogallol as substrate, and with glutathione and sodium azide inhibitors using catechol as substrate. From these results, it can be said that the most effective inhibitor for artichoke PPO is tropolone. Furthermore, it was found that the type of inhibition depended on the origin of the PPO studied and also on the substrate used.

Catechol Oxidase↗
PubMed1987

Effects of extraneuronal uptake inhibitors on the positive chronotropic response to isoprenaline and on the accumulation of isoprenaline in perfused rat heart after inhibition of catechol-O-methyl transferase.

Experiments were carried out in isolated perfused rat hearts. The presence of tropolone (100 mumol/l), an inhibitor of catechol-O-methyl transferase (COMT), significantly potentiated the positive chronotropic response to isoprenaline (0.1, 1, 3 and 10 nmol/l). Two uptake2 inhibitors, 3-O-methylisoprenaline (100 mumol/l) and normetanephrine (100 mumol/l), induced a positive chronotropic response, but corticosterone (100 mumol/l) and hydrocortisone (100 mumol/l) had no such effect. 3-O-methylisoprenaline (100 mumol/l) and normetanephrine (100 mumol/l) enhanced the positive chronotropic response to isoprenaline (0.1, 1, 3 and 10 nmol/l). Corticosterone (100 mumol/l) potentiated the positive chronotropic response to isoprenaline (0.1 and 1 nmol/l). Hydrocortisone (30 mumol/l) enhanced the response to 0.1 nmol/l isoprenaline but did not affect the positive chronotropic responses to 1, 3 or 10 nmol/l isoprenaline. The addition of uptake2 inhibitors (3-O-methylisoprenaline, 100 mumol/l; normetanephrine, 100 mumol/l; corticosterone, 100 mumol/l) to the perfusion medium significantly reduced the positive chronotropic response to the perfusion with isoprenaline (3 nmol/l) and tropolone (100 mumol/l). The accumulation of 3H-isoprenaline in the heart perfused with 3H-isoprenaline (1, 10 and 100 nmol/l) was significantly increased by the presence of tropolone (100 mumol/l): the accumulation for 1, 10 and 100 nmol/l of 3H-isoprenaline was 5.07, 47.0 and 500 pmol/g, respectively. The high accumulation observed during perfusion with 3H-isoprenaline (3 nmol/l) and tropolone (100 mumol/l) was significantly decreased by the addition of an uptake2 inhibitor, 3-O-methylisoprenaline (100 mumol/l), normetanephrine (100 mumol/l) or corticosterone (100 mumol/l), but not by hydrocortisone (30 mumol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Comparative evaluation of red cell-labeling parameters of three lipid-soluble- 111In-chelates: effect of lipid solubility on membrane incorporation and stability constant on transchelation.

A rabbit red cell model was used to determine the cell labeling properties of three lipid-soluble 111In-complexes: 111In-oxine, 111In-acetylacetone, and 111In-tropolone. Partition coefficients (olive oil/buffer) were measured to determine the lipid solubility and were 3.54, 7.93, and 18.18 for 111In-oxine, 111In-acetylacetone, and 111In-tropolone respectively. The effect of the concentration of these three chelating agents on labeling efficiencies was studied. The factors influencing the labeling efficiencies of these complexes such as cell density, time of incubation, influence of temperature, pH, effect of plasma proteins, and citrate ion concentration in the cell-labeling medium were studied. Labeling yields as high as 95.15 +/- 4.15% were achieved with 111In-tropolone after a 10-min incubation at 37 degrees C. The optimum pH for cell labeling was 6.5. Excess citrate ion (greater than 3.02 mg/ml) and small amounts of plasma proteins (greater than 10 microliter/ml) decreased the labeling efficiencies in all three cases. Distribution of these 111In-complexes in membrane, membrane fragments, and hemoglobin was studied after hemolysis. In spite of the higher lipid solubility of 111In-tropolone, the transchelation capacity appears to be similar to that of 111In-oxine. 111In-acetylacetone had the highest transchelation capacity.

Animals↗
PubMed1998

Fungitoxicity of chemical analogs with heartwood toxins.

Trans-stilbene and tropolone as chemical analogs with naturally occurring fungitoxic heartwood compounds were studied with respect to their fungitoxic potency. While stilbene showed no fungitoxic activity towards the fungi Aureobasidium pullulans var. melanogenum, Penicillium glabrum, and Trichoderma harzianum in the concentrations tested, the minimal inhibiting concentration of tropolone was 10(-3) M for Penicillium glabrum and Trichoderma harzianum, and 10(-5) M for Aureobasidium pullulans var. melanogenum. In all cases, the effect of tropolone was a fungistatic one. Using chemical analogs for assessing the chemical basis of the fungitoxicity of tropolone, this substance proved to be the only compound tested which possesses fungitoxic properties.

Fungi↗
PubMed1984

Formation and clearance of norepinephrine glycol metabolites in mouse brain.

To determine the degree of conversion of 3,4-dihydroxyphenylethyleneglycol (DHPG) to 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) and the amount of DHPG eliminated unchanged from the brain, we have examined the kinetics of formation and disappearance of mouse brain MHPG and DHPG following clorgyline (10 mg/kg, i.p.) and/or tropolone (75 mg/kg, i.p.) treatment. During the first 10 min after tropolone, brain DHPG levels accumulated linearly at a rate of 1,300 pmol/g/h, whereas MHPG disappeared exponentially at a rate of 411 pmol/g/h. Following clorgyline administration, brain DHPG declined exponentially at a rate of 1,240 pmol/g/h. In contrast, the elimination of MHPG became a first-order process only when catechol-O-methyltransferase (COMT) was also inhibited in addition to monoamine oxidase. Thus, combined clorgyline and tropolone treatment resulted in an exponential decline of MHPG levels at a rate of 524 pmol/g/h, whereas DHPG levels were slightly but significantly elevated compared to control values. When the animals were treated with pargyline (75 mg/kg, i.p.) in combination with clorgyline and tropolone, brain DHPG and MHPG disappeared at rates of 40 and 660 pmol/g/h, respectively. The above observations suggest that mouse brain DHPG is cleared primarily through O-methylation with minimal direct elimination from brain. Assuming the disposition and clearance of norepinephrine metabolites are similar in mouse and human brain, peripherally measured DHPG in humans is likely derived principally from extracerebral sources and reflects peripheral sympathetic function.

Animals↗
PubMed1999

Effect of tyrosinase inhibitors on Tuber borchii mycelium growth in vitro.

This paper reports the effect of the tyrosinase (monophenol o-diphenol:oxygen oxidoreductase; EC 1.14.18.1) inhibitors diethyldithiocarbamate (DETC), L-tropolone, kojic acid, phenylthiourea (PTU) and L-mimosine on the in vitro growth of Tuber borchii (a white truffle) mycelium. A significant inhibitory effect on mycelium growth was observed for DETC, PTU and L-tropolone (0% growth compared to control at 100 microg ml(-1) DETC, PTU and L-tropolone and at 10 microg ml(-1) DETC and L-tropolone). As a comparison the action of the same inhibitors was also tested on the growth and pigmentation of the mould Cladosporium sphaerospermum. In the presence of CuSO(4) 10(-6) M T. borchii mycelium acquired pigmentation (as rounded aggregates compared to control revealed by SEM microscopy). Tyrosinase activity in the extract from T. borchii mycelium (18-day culture) was detected spectrophotometrically.

Ascomycota↗
PubMed1975

Studies on the temperature-dependent sensitivity of mouse atria to adrenergic drugs.

The sensitivity of mouse atria (chronotropic response) to beta-adrenergic receptor antagonists was examined at 37 and 26 degrees C under various experimental conditions. When isoproterenol was used as agonist, at 37 degrees C, the pA2 value (from pA2 plots) for propranolol was 8.86 and the slope of the regression line was 0.54. At 26 degrees C, the pA2 value for propranolol was 9.2 and the slope was 0.7. In the presence of tropolone, 10-5 M, the values for pA2 and slope of the regression lines were, respectively, 9.0 and 0.90 at 37 degrees C and 9.17 and 0.98 at 26 degrees C. In other words, decreasing antagonism was prevented by low temperature and tropolone. Isoproterenol was potentiated by tropolone and low temperature, but the effects of low temperature were reduced by tropolone. With sotalol as antagonist, there was greated blockade (dose ratios) of the effects of isoproterenol at 26 than at 37 degrees C. When nylidrin, a non-catecholamine, was used as agonist there was no temperature-dependent sensitivity to sotalol. Furthermore, nylidrin was not potentiated by low temperature. The data show that the observed degree of beta-receptor antagonism can be altered by changing the bath temperature and suggest that this effect is related to COMT activity or an influence of agonist disposition in the tissue.

Adrenergic beta-Antagonists↗
PubMed1985

Changes in the incidence and duration of ventricular fibrillation in dependence on the extraneuronal accumulation of isoprenaline in the perfused rat heart.

The relationship between the accumulation of isoprenaline and the incidence and duration of ventricular fibrillation was investigated in the perfused rat heart. Isolated rat hearts were perfused with 3H-isoprenaline (1 mumol/l) for 30 min at a constant flow rate of 6.5 ml/min at a temperature between 40 and 41 degrees C. Electrocardiograms were recorded during the perfusion period and the isoprenaline content of the tissue was measured after the perfusion. The accumulation of isoprenaline was significantly increased and the duration of ventricular fibrillation was significantly prolonged by the presence of tropolone (100 mumol/l). When extraneuronal uptake inhibitors such as normetanephrine (100 mumol/l), 3-O-methylisoprenaline (100 mumol/l) or phenoxybenzamine (1 mumol/l) were added to the perfusion fluid containing 3H-isoprenaline (1 mumol/l) and tropolone (100 mumol/l), the accumulation of isoprenaline was significantly decreased, the incidence of ventricular fibrillation was significantly reduced and the duration of ventricular fibrillation was significantly shortened. There was a significant correlation for dependence of duration of ventricular fibrillation on the isoprenaline content of rat hearts perfused with various extraneuronal uptake inhibitors in the presence of tropolone (correlation coefficient [r] = 0.62, P less than 0.001). These results indicate that the accumulation of isoprenaline in perfused rat hearts relates to the occurrence and duration of ventricular fibrillation.

Animals↗
PubMed1995

Glial alpha 2-receptors probably inhibit the high-affinity uptake of noradrenaline into astrocytes in the rat brain in vivo.

The effect of alpha 2-receptor blockage on the extraneuronal turnover of noradrenaline (NA) has been studied in the intact rat brain. Tropolone and yohimbine, along with reserpine or desmethylimipramine, were given 30 min after intracerebroventricular injection of [7-3H]NA, i.e. after the tracer had been stored or inactivated. Tropolone given alone did not change the fractions of 3H-activity recovered as [3H]NA from hypothalamus, septum, striatum and pons-medulla, but in the presence of yohimbine improved the [3H]NA recovery in all areas except pons-medulla. The maximum effect was seen in the hypothalamus of reserpine-treated rats. Since the alpha 2-autoreceptors were blocked, the increased [3H]NA recovery does not reflect a down-regulated neuronal NA turnover. Instead it seems to show that a fraction greater than normal of neuronally released NA had been taken up into astrocytes and remained unmetabolized if catechol-O-methyltransferase was inactive. It is assumed that yohimbine enabled the protective tropolone effect by blocking astrocytic alpha 2-receptors that otherwise, either by itself or by antagonizing beta-receptor-induced hyperpolarization or cAMP formation, had impaired parameters that stimulate the high-affinity NA Uptake 1 of astrocytes (e.g. membrane potential, Na+,K(+)-ATPase) or control the gap junction permeability in the glial syncytium.

Adrenergic alpha-Antagonists↗
PubMed1994

Small molecule probes of glyoxalase I and glyoxalase II.

A number of synthetic tropolones and hydrophobic S-blocked glutathione analogues were investigated as potential inhibitors of glyoxalase I from Saccharomyces cerevisiae and glyoxalase II from bovine liver. Several tropolones containing a free C-2 hydroxy group were found to be potent inhibitors of glyoxalase I, whereas the glutathione conjugates were found to be modest to poor inhibitors of this enzyme. Most tropolones and glutathione conjugates, except 5-p-tolylazotropolone and S-carbobenzoxy-L-glutathione, were found to be poor inhibitors of glyoxalase II. A recent report on an extremely active glyoxalase system from Plasmodium falciparum suggested that several of the more potent inhibitors may have antimalarial properties. A number of these compounds in fact, exhibited antimalarial activity in the low micromolar range. Further studies are required to fully elucidate the mechanism(s) of the antimalarial properties of these compounds.

Animals↗
PubMed1986

Comparison of three platelet markers for measurement of platelet survival time in healthy volunteers.

We studied mean platelet survival times in healthy volunteers with use of [51Cr]disodium chromate, 111In-oxine (in a solution of acid-citrate-dextrose [ACD] and saline), and 111In-tropolone (in ACD-plasma) as markers. Differences found between the 51Cr and 111In labels probably can be attributed to a variation in localization of the label on the cell and of renal handling of the free label after release. The mean platelet survival time with 51Cr was slightly longer than the survival time with both indium labels and showed a sex difference not seen with 111In-oxine. Protein-bound plasma 51Cr was lower than plasma 111In and remained constant throughout the study. Plasma 111In increased with time. For survival time calculations, no correction for free 51Cr is necessary, but correction should routinely be performed when 111In markers are used. Both 111In markers gave similar results with respect to platelet survival time. The somewhat more elaborate plasma labeling procedure with tropolone shows no measurable advantage over the original 111In-oxine method. 111In-tropolone labeling takes less time and maintains platelets in the physiologic environment of plasma during incubation. Biodistribution studies show no difference between the two 111In markers.

Blood Platelets↗
PubMed1988

New inhibitors for aminoglycoside-adenylyltransferase.

Two hydroxymethyltropolones and two tropolone acetate derivatives were found to inhibit an aminoglycoside-adenylyltranferase in a gentamicin-resistant Escherichia coli strain. The inhibitory effect of tropolones depends on the nature of the aminoglycoside antibiotic subject to adenylation. Combinations of hydroxymethyltropolones with tobramycin were more active compared with tropolone acetates against gentamicin-resistant strains displaying adenylyltransferase activity. On the contrary a combination of the investigated acetate with gentamicin was of lower activity. It could be shown that these inhibitors inhibit, to a varying degree, the transfer of radioactive ATP to different aminoglycoside molecules.

Cycloheptanes↗
PubMed2006

Delineating the role of polyphenol oxidase in the darkening of alkaline wheat noodles.

This study evaluated the effects of inhibitors on polyphenol oxidase (PPO) activity, the effect of the PPO inhibitor tropolone on noodle darkening, and the correlation of PPO activity with darkening of alkaline noodles. The PPO inhibitors tropolone and salicylhydroxamic acid (each at 1 microM) reduced kernel PPO activity by approximately 50% in three hexaploid wheat cultivars but did not inhibit PPO activity in the two very low PPO cultivars, durum Langdon, and the synthetic hexaploid-derived ID580. Tropolone (100 microg/g flour) inhibited alkaline noodle darkening (deltaL*) by 13-25% in the low PPO wheat cultivar, ID377s, and by 39-54% in the high PPO wheat cultivar, Klasic. Alkaline noodle darkening among 502 wheat samples was correlated with kernel PPO activity (r = 0.64). Results substantiate the hypothesis that PPO plays a major role in darkening of alkaline noodles. However, results also indicate that substantial darkening would occur even at zero PPO activity, as measured in the kernel PPO assay. Therefore, darkening of alkaline noodles is probably due to the cultivar-specific level of PPO activity and the presence of at least one additional darkening mechanism. Further investigation is required to identify the phenolic discoloration agent(s) and to determine the potential roles of non-PPO discoloration mechanisms, both enzymatic and nonenzymatic, in wheat products.

Catechol Oxidase↗
PubMed1989

Use of indium-111 as a red cell label.

To select the most promising 111In chelate for use as a second red cell (RBC) label for comparison of the survival of autologous and allogeneic cells, 49 normal RBC samples were studied in vitro after being labeled with 111In-8-hydroxyquinolinol (111In-oxine) prepared by three different methods, 111In-tropolone, and 111In-acetylacetone. Labeling efficiencies reached 99 percent and did not decline when the amount of 111In used was increased from 1.75 to 50 muCi per ml of RBCs. Storage of labeled RBCs in normal AB plasma at 4, 22, and 37 degrees C for up to 48 hours resulted in a similar rate of loss of the label from the RBCs with all labeling methods. These rates were time- and temperature-dependent and were accurate predictions of the rates found in later in vivo experimentation. Fresh RBCs from 11 subjects were labeled with 111In chelated with oxine in the presence of the RBCs or chelated with tropolone just prior to the labeling. RBC mass determinations using these autologous RBCs labeled with 111In accurately reflected the subjects' RBC masses as predicted through standard morphometric formulae. The rate of disappearance of the radionuclide after reinfusion of the autologous RBCs decreased with time. At 24 hours after reinfusion, 89.5 +/- 1.29 percent (mean +/- SEM) of the 111In-tropolone and 87.3 +/- 1.25 percent of the 111In-oxine continued in circulation. 111In is a simple and efficient agent for the labeling of RBCs for blood volume determinations and short-term survivals.

Blood Volume↗