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PubMed2000

Role of adenine functional groups in the recognition of the 3'-splice-site AG during the second step of pre-mRNA splicing.

The AG dinucleotide at the 3' splice sites of metazoan nuclear pre-mRNAs plays a critical role in catalytic step II of the splicing reaction. Previous studies have shown that replacement of the guanine by adenine in the AG (AG --> GG) inhibits this step. We find that the second step was even more severely inhibited by cytosine (AG --> CG) or uracil (AG --> UG) substitutions at this position. By contrast, a relatively moderate inhibition was observed with a hypoxanthine substitution (AG --> HG). When adenine was replaced by a purine base (AG --> PG) or by 7-deazaadenine (AG --> c(7)AG), little effect on the second step was observed, suggesting that the 6-NH(2) and N(7) groups do not play a critical role in adenine recognition. Finally, replacement of adenine by 2-aminopurine (AG --> 2-APG) had no effect on the second step. Taken together, our results suggest that the N(1) group of adenine functions as an essential determinant in adenine recognition during the second step of pre-mRNA splicing.

Adenine↗
PubMed2000

Gelonin is an unusual DNA glycosylase that removes adenine from single-stranded DNA, normal base pairs and mismatches.

We reported that plant ribosome inactivating proteins (RIP) have a unique DNA glycosylase activity that removes adenine from single-stranded DNA (Nicolas, E., Beggs, J. M., Haltiwanger, B. M., and Taraschi, T. F. (1998) J. Biol. Chem. 273, 17216-17220). In this investigation, we further characterized the interaction of the RIP gelonin with single-stranded oligonucleotides and investigated its activity on double-stranded oligonucleotides. At physiological pH, zinc and beta-mercaptoethanol stimulated the adenine DNA glycosylase activity of gelonin. Under these conditions, gelonin catalytically removed adenine from single-stranded DNA and, albeit to a lesser extent, from normal base pairs and mismatches in duplex DNA. Also unprecedented was the finding that activity on single-stranded and double-stranded oligonucleotides containing multiple adenines generated unstable products with several abasic sites, producing strand breakage and duplex melting, respectively. The results from competition experiments suggested similar interactions between gelonin's DNA-binding domain and oligonucleotides with and without adenine. A re-examination of the classification of gelonin as a DNA glycosylase/AP lyase using the borohydride trapping assay revealed that gelonin was similar to the DNA glycosylase MutY: both enzymes are monofunctional glycosylases, which are trappable to their DNA substrates. The k(cat) for the removal of adenine from single-stranded DNA was close to the values observed with multisubstrate DNA glycosylases, suggesting that the activity of RIPs on DNA may be physiologically relevant.

Adenine↗
PubMed2006

An efficient synthesis of acyclic N7- and N9-adenine nucleosides via alkylation with secondary carbon electrophiles to introduce versatile functional groups at the C-1 position of acyclic moiety.

The introduction of versatile functional groups, allyl and ester, at the C-1 position of the acyclic chain in acyclic adenine nucleosides was achieved for the first time directly by alkylation of adenine and N6-potected adenine. Thus, the C-1'-substituted N9-adenine acyclic nucleoside, adenine-9-yl-pent-4-enoic acid ethyl ester (11), was prepared by direct alkylation of adenine with 2-bromopent-4-enoic acid ethyl ester (6), while the corresponding N7-regioisomer, 2-[6-(dimethylaminomethyleneamino)-purin-7-yl]-pent-4-enoic acid ethyl ester (10), was obtained in one step by the coupling of N, N-dimethyl-N'- (9H-purin-6-yl)-formamidine (9) with 2-bromopent-4-enoic acid ethyl ester (6). The functional groups, ester and allyl, were converted to the desired hydroxymethyl and hydroxyethyl groups, and subsequently to phosphonomethyl derivatives and corresponding pyrophosphorylphosphonates.

Adenine↗
PubMed1975

Transfer of adenine nucleotides between the releasable and nonreleasable compartments of rabbit blood platelets.

The metabolic pool of adenine nucleotides in platelets can be labeled by incubating platelets for 1 h in vitro with [14C]adenosine or [32P]orthophosphate. When these platelets are treated with thrombin, the adenine nucleotides released are not labeled. Because of this, Holmsen's suggestion of a metabolically inert pool of granule nucleotides has been generally accepted. We have found that upon incubation of labeled rabbit platelets for longer times (up to 6 h) in vitro, or upon reinjection and reharvesting at times up to 66 h, the releasable pool of adenine nucleotides becomes labeled. Because the rates of 32p and 14C incorporation into this releasable pool are similar, it seems likely that these labels enter the granules as ATP. Equilibrium between the metabolic and granule pools is complete by 18 h. When rabbit platelets are labeled in vivo by intravenous injection of [32P]orthophosphate, peak labeling occurs between 60 and 70 h; this corresponds to their maturation time. The platelets probably incorporate 32P during their production in the megakaryocytes. The specific radioactivity of the adenine nucleotides in the releasable (granule) pool of these platelets is the same as the specific radioactivity in the nonreleasable (metabolic) pool. Since inorganic phosphate in platelets (and undoubtedly in the megakaryocytes) exchanges with inorganic phosphate in plasma, and since the radioactivity of the latter decreases rapidly, the adenine nucleotides in the two pools must exchange to maintain the same specific radioactivity. Transfer of adenine nucleotides into storage granules may represent a general phenomenon because it has been observed in the chromaffin cells of the adrenal medulla also.

Adenine Nucleotides↗
PubMed1990

Adenine nucleotide depletion and contractile dysfunction in the "stunned" myocardium.

STUDY OBJECTIVE: The aim of the study was to assess the contribution of adenine nucleotide depletion to postischaemic myocardial dysfunction ("stunned" myocardium). DESIGN: Isolated perfused hearts release purine catabolites even in the absence of ischaemia, and undergo spontaneous reduction of adenine nucleotide pool. A comparison was therefore made between mechanical function, purine release and tissue adenine nucleotides in working rat hearts reperfused after short term ischaemia or subjected to prolonged perfusion (up to 180 min). EXPERIMENTAL MATERIAL: 49 Sprague-Dawley rats of 250-300 g body weight were used. The animals were anaesthetised and the hearts quickly excised and perfused with the working heart technique. MEASUREMENTS AND MAIN RESULTS: Reperfusion after 10 min ischaemia provided a good model of "stunned" myocardium: aortic flow and minute work decreased by 15(SEM 2)% and 20(3)%, no enzyme leakage was observed, and the adenine nucleotide pool decreased by 3.5(0.4) mumols.g-1. During prolonged perfusion no change was observed in any haemodynamic variable until the adenine nucleotide pool was depleted by over 8.5 mumols.g-1. Adenylate energy charge and the phosphocreatine-creatine pool were unchanged in all cases. CONCLUSIONS: Depletion of adenine nucleotides does not account for contractile dysfunction in our model of "stunned" myocardium.

Adenine Nucleotides↗
PubMed1990

DNA with adenine tracts contains poly(dA).poly(dT) conformational features in solution.

The conformation of DNA's with adenine-thymine tracts exhibiting retardation in electrophoretic migration and considered as curved were investigated in solution by CD and RAMAN spectroscopy. The following curved multimers with adenine tracts but of different flanking sequences d(CA5TGCC)n, d(TCTCTA6TATATA5)n, d(GA4T4C)n yield CD spectroscopic features indicating a non-B structure of the dA.dT tract with similarities to polyd(A).polyd(T). We suggest that adenine-thymine bases in these multimers contain some of the distinctive conformational features of poly(A).polyd(T) probably with large propeller twist found by NMR (Behling and Kearns, 1987) and by X-ray diffraction on oligonucleotides containing a tract of adenines (Nelson et al. 1987, Coll et al; 1987; DiGabriele et al. 1989). Some elements of distinctive CD features of the contiguous adenines run are also observed in the straight multi-9-mer d(CA5GCC)n which lacks in-phase relation to the helical repeat. Despite the presence of the TpA step in the straight multimer d(GT4A4)n, the altered dA.dT conformation is not completely destroyed. Interruption of adenine tract by a guanine in d(CAAGAATGCC)n leads to a B-like conformation and to a normal electrophoretic mobility. The Raman spectra reveal a rearrangement of the sugar-phosphate backbone of dA.dT tract in the multimer d(CA5TGCC)n with respect to that of polydA.polydT. This is reflected in the presence of an unique Raman band associated to C2'-endo sugar with a predominant contribution of C1'-exo puckering which is exhibited by the multimer whereas two distinct Raman bands characterize poly(dA).poly(dT) backbone conformation.

Adenine↗
PubMed1991

Adenine photodimerization in deoxyadenylate sequences: elucidation of the mechanism through structural studies of a major d(ApA) photoproduct.

The mechanism of the photodimerization of adjacent adenine bases on the same strand of DNA has been elucidated by determining the structure of one of the two major photoproducts that are formed by UV irradiation of the deoxydinucleoside monophosphate d(ApA). The photoproduct, denoted d(ApA)*, corresponds to a species of adenine photodimer first described by Pörschke (Pörschke, D. (1973) J.Am.Chem.Soc. 95, 8440-8446). From a detailed examination of its chemical and spectroscopic properties, including comparisons with the model compound N-cyano-N1-(1-methylimidazol-5-yl)formamidine, it is deduced that d(ApA)* contains a deoxyadenosine unit covalently linked through its C(8) position to C(4) of an imidazole N(1) deoxyribonucleoside moiety bearing an N-cyanoformamidino substituent at C(5). On treatment with acid, d(ApA)* is degraded with high specificity to 8-(5-amino-imidazol-4-yl)adenine whose identity has been confirmed by independent chemical synthesis. It is concluded that the primary event in adenine photodimerization entails photoaddition of the N(7)-C(8) double bond of the 5'-adenine across the C(6) and C(5) positions of the 3'-adenine. The azetidine species thus generated acts as a common precursor to both types of d(ApA) photoproduct which are formed from it by competing modes of azetidine ring fission.

Adenine↗
PubMed1980

Transfer RNA structure by carbon NMR: C2 of adenine, uracil and cytosine.

Fourier transform 13C NMR spectra of E. coli tRNA enriched on 13C in either position 2 of adenine (60 atom % 13C) or in position 2 of uracil (82%) and cytosine (63%) were taken at 25.16 MHz over the temperature range 10 degrees - 76 degrees. For C2 of adenine the peak as initially 5 ppm wide, but narrowed to 0.5 ppm as the molecule unfolded. C2 of uracil displayed behavior similar to that of adenine while the cytosine peak, initially relatively narrow at low temperature, sharpened less dramatically. Comparison of spectra at 26.16 MHz and 67.9 MHz showed that the peak widths for folded tRNA were determined largely by chemical shift non-equivalence. T2 T2 measurements suggested that intrinsic line widths of most cytosine C2 peaks were 4 Hz and 2-3 Hz for uracil. Adenine C2 with a directly bonded proton had resonances of about 40 Hz line width. T1 values were measured for C2 of adenine and the ribose carbons of tRNA. Consideration of dipolar relaxation and chemical shift anisotrophy led to a calculated rotational correlation time of 1.6 +/- 0.4 x 10(-8) sec for the adenines and 1.3 +/- 0.3 x 10(-8) sec for the ribose carbons.

Adenine↗
PubMed1977

A correlation between the secondary structure of DNA and the reactivity of adenine residues with chloroacetaldehyde.

The rate of reaction of chloroacetaldehyde (0.039 M) with the "free" adenine residue in deoxyadenosine-5'-phosphate (dAMP) at pH 6.5 has been found to be nearly equal to that at pH 4.5. Practically 100% of the adenine is converted to a fluorescent product (epsilon-adenine residue) on incubation for 60 h at 37 degrees C and pH 6.5. Of the adenine residues in "single-stranded" DNA, however, only 14% react with chloroacetaldehyde (0.039 M) under the same incubation conditions. The reaction rate of this 14% is nearly equal to that of dAMP, but the fluorescence of the product is appreciably quenched; the quantum yield is only 0.45 times that of the "free" adenine residue. In "double-helical" DNA, on the other hand, no adenine residue has been found to react with chloracetaldehyde. Possible application of these findings to structural studies of DNA is suggested.

Acetaldehyde↗
PubMed1983

Decrease in mitochondrial levels of adenine nucleotides and concomitant mitochondrial dysfunction in ischemic rat liver.

The process of mitochondrial dysfunction in ischemic rat liver was studied. A close correlation was found between decrease in the mitochondrial adenine nucleotide content and deterioration of oxidative phosphorylation capacity. The level of total adenine nucleotides, which was 15--20 nmol/mg protein in mitochondria isolated from normal liver, fell to 1--2 nmol/mg protein with concomitant loss of oxidative phosphorylation capacity after anoxic incubation in vitro or in vivo for 120 min. However, neither the permeability barrier to adenine nucleotides nor matrix enzymes were affected under these conditions. The loss of adenine nucleotides was ascribed to degradation of AMP to adenosine and then leakage of the latter. Conventional procedures for maintenance of oxidative phosphorylation capacity of isolated mitochondria, preservation in the cold and addition of ATP or a respiratory substrate under aerobic conditions, were very effective in maintaining the intramitochondrial levels of adenine nucleotides. Of the three species of adenine nucleotides, only AMP was ineffective in maintaining mitochondrial function; mitochondria containing more than 5 nmol of ATP plus ADP/mg protein exhibited normal activity of oxidative phosphorylation, but with less than 2 nmol they showed no activity.

Adenine Nucleotides↗
PubMed1985

Effect of adenine, cytidine and guanosine on the expression of the SOS system in Escherichia coli.

Addition of cytidine or guanosine to UV-irradiated cells of a RecA+ strain of Escherichia coli did not produce any effect on the induction of two SOS functions: inhibition of cell division and expression of the umuC gene. Under the same conditions adenine gave a slight increase in the induction of these two responses. In a RecA441 mutant growing at 42 degrees C, both cytidine and guanosine inhibited these SOS functions, whereas adenine produced a large increase in their expression. Moreover, the ATP concentration of the RecA441 mutant at 42 degrees C showed a decrease which occurred earlier in the cells growing in the presence of cytidine or guanosine than in the absence of either compound. Adenine induced an increase of about three times the initial ATP concentration of this mutant at 42 degrees C which dropped quickly after 10 min. Neither cytidine nor guanosine increased the evolution of cellular ATP in UV-irradiated cells of the RecA+ strain, whereas adenine had only a slight positive effect. However, in UV-irradiated RecA+ cells with and without adenine, ATP levels dropped quickly to the initial value after 20 min. These data suggest that the influence of adenine, cytidine and guanosine on the expression of the RecA441 phenotype at 42 degrees C may be due to alteration of the cellular ATP concentration of this mutant.

Adenine↗
PubMed1992

Measurement of thyroid-stimulating immunoglobulins by incorporation of tritiated-adenine into intact FRTL-5 cells: a viable alternative to radioimmunoassay for the measurement of cAMP.

OBJECTIVE: To evaluate the utility of 3H-adenine incorporation into intact rat thyroid epithelial cells (FRTL-5) as an alternative to radioimmunoassay for the measurement of cAMP following stimulation of these cells by serum thyroid-stimulating immunoglobulins from patients with Graves' disease. DESIGN: We determined the cAMP produced by FRTL-5 cells following incubation with serum from patients with a spectrum of autoimmune thyroid and other diseases using the 3H-adenine assay. PATIENTS: We studied 27 patients with untreated Graves' disease, 10 with Graves' disease complicated by ophthalmopathy (all on antithyroid medication), 11 with Hashimoto's thyroiditis, five with multinodular goitre, one with thyroid carcinoma, 23 with type 1 diabetes mellitus, 19 with other autoimmune diseases and 10 controls. MEASUREMENTS: The 3H-cAMP produced in cells incubated with either bovine TSH (bTSH) or polyethylene glycol-precipitated serum immunoglobulins, was separated by sequential chromatography on Dowex and alumina columns, and counted. The thyroid-stimulating immunoglobulins index (3H-cAMP patient immunoglobulins/3H-cAMP control immunoglobulins) was calculated for each serum and considered positive if greater than 1.5 (+ve thyroid-stimulating immunoglobulins index, i.e. > 2 standard deviations above control). The thyroid-stimulating immunoglobulins index was correlated with measurement of thyrotrophin binding inhibitory immunoglobulins (TBII) by radioreceptor assay. RESULTS: The 3H-adenine assay has a sensitivity of 10(-11) M bTSH with maximal stimulation at 10(-9) M bTSH (30-fold). Twenty-five of 27 patients (92%) with untreated Graves' disease and four of 10 patients with Graves' disease complicated by ophthalmopathy had +ve thyroid-stimulating immunoglobulin indices. The thyroid-stimulating immunoglobulins index in patients with untreated Graves' disease correlated with their TBII assay result (r = 0.63, P < 0.001). In addition, the index was negative in patients with Hashimoto's thyroiditis, multinodular goitre, thyroid carcinoma, and type 1 diabetes mellitus. Of the patients with other autoimmune diseases only one (a patient with systemic lupus erythematosis) had a +ve thyroid-stimulating immunoglobulin index. Direct comparison of cAMP measurement by 3H-adenine incorporation and commercial radioimmunoassay showed an equal sensitivity to both bTSH and Graves' immunoglobulins. After cell preparation, results are obtained more quickly with the 3H-adenine assay than with a cAMP radioimmunoassay (5 hours compared to 2 days), and far more cheaply than by commercial radioimmunoassays. CONCLUSIONS: Measurement of thyroid-stimulating immunoglobulins using the incorporation of 3H-adenine into cAMP in FRTL-5 cells is sensitive, reproducible, rapid and specific. These features make this assay a viable alternative to RIA for the measurement of thyroid-stimulating immunoglobulins in patients with Graves's disease.

Adenine↗
PubMed1986

Preservation of red blood cells: content of microaggregates and di-2-ethylhexylphthalate (DEHP) in red blood cells stored in saline-adenine-glucose-mannitol (SAGM) medium.

The content of microaggregates was determined in leukocyte-poor red blood cells (RBC) after 5 weeks of storage in citrate-phosphate-dextrose (CPD)-adenine plasma and in saline-adenine-glucose-mannitol (SAGM) medium. The size range was 3,600-200,000 fl, corresponding to a particle diameter of 19-73 micron, presuming a spherical particle shape. In comparison with CPD-adenine whole blood (100%), the total number of particles per unit of RBC was found to be 41.2% (CPD-adenine anticoagulant) and 25.4% (SAGM medium). The corresponding data for total particle volumes were 43.3 and 30.3%. The significant differences between the two categories of RBC could not be explained on the basis of differences concerning pH or cell composition. A majority of particles (50-62%) was observed in the lowest size range (19-29 microns), corresponding to only 18-26% of the total particle volume. The accumulation of di-2-ethylhexylphthalate (DEHP) was determined in two variations of RBC stored in SAGM medium and in RBC stored in CPD-adenine plasma. The quantities of DEHP per unit of RBC after 5 weeks were significantly smaller in SAGM medium (9.0 +/- 3.6 and 22.7 +/- 6.1 mg, respectively) compared to CPD-adenine plasma (30.1 +/- 9.5 mg).

Adenine↗
PubMed1986

Turnover and storage of newly synthesized adenine nucleotides in bovine adrenal medullary cell cultures.

The adenine nucleotide stores of cultured adrenal medullary cells were radiolabeled by incubating the cells with 32Pi and [3H]adenosine and the turnover, subcellular distribution, and secretion of the nucleotides were examined. ATP represented 84-88% of the labeled adenine nucleotides, ADP 11-13%, and AMP 1-3%. The turnover of 32P-adenine nucleotides and 3H-nucleotides was biphasic and virtually identical; there was an initial fast phase with a t1/2 of 3.5-4.5 h and a slow phase with a half-life varying from 7 to 17 days, depending upon the particular cell preparation. The t1/2 of the slow phase for labeled adenine nucleotides was the same as that for the turnover of labeled catecholamines. The subcellular distribution of labeled adenine nucleotides provides evidence that there are at least two pools of adenine nucleotides which make up the component with the long half-life. One pool, which contains the bulk of endogenous nucleotides (75% of the total), is present within the chromaffin vesicles; the subcellular localization of the second pool has not been identified. The studies also show that [3H]ATP and [32P]ATP are distributed differently within the cell; 3 days after labeling 75% of the [32P]ATP was present in chromaffin vesicles while only 35% of the [3H]ATP was present in chromaffin vesicles. Evidence for two pools of ATP with long half-lives and for the differential distribution of [32P]ATP and [3H]ATP was also obtained from secretion studies. Stimulation of cell cultures with nicotine or scorpion venom 24 h after labeling with [3H]adenosine and 32Pi released relatively twice as much catecholamine as 32P-labeled compounds and relatively three times as much catecholamine as 3H-labeled compounds.

Adenine Nucleotides↗
PubMed1988

Liver adenosine triphosphate and pH in fasted and well-fed mice after infusion of adenine nucleotide precursors.

Nutrition is a factor which may affect the liver energy charge. Experiments were performed to determine the effect of starvation and of ATP precursors, adenine and ribose on liver energy stores. The 31P NMR spectra of well-fed and starved mice livers were studied in a perfusion system using Krebs-Henseleit buffer (KHB). The ATP precursors, adenine (20 mmol/l) and ribose (80 mmol/l), were then added to determine their effect. Their effect on the ATP dynamics during ischemia and reperfusion were then evaluated. The effects of adenine alone and ribose alone were then determined. The 31P spectra of well-fed mice demonstrated high ATP content relative to Pi, phosphoesters and phospholipids. Animals starved for 24 h showed very low ATP, high Pi and little or no detectable phospholipids. In starved animals, ATP rose steadily to approximately 50% above the baseline level when precursors were added. Pi decreased to 30% of the baseline after 40 min. Little change was noted in well-fed animals. The rate of ATP decay did not change with the onset of ischemia, whether the livers were perfused with KHB alone or KHB with precursors. Upon reperfusion, precursors improved the recovery of ATP (81% vs 49% after 20 min ischemia, 44% vs 34% after 30 min ischemia). Addition of adenine alone produced similar results, but addition of ribose alone did not significantly alter ATP recovery. In conclusion, supplying starved or post-ischemic livers with adenine or ribose and adenine does improve ATP levels.

Adenine↗
PubMed1986

Adenine nucleotides in cultured brain cells after exposure to methyl mercury and triethyl lead.

To obtain more information on the biochemical background, of methyl mercury (MeHg) and triethyl lead (Et3Pb) toxicity, the doses which were needed to alter the cellular content of adenine nucleotides were compared to doses which induced morphological alterations. Three-week-old cultures of brain cells from new-born rat were incubated for 5-60 min. with 28, 16, and 8 X 10(-6) M MeHg or with 3 X 10(-6) M Et3Pb in the nutrition medium. MeHg at 28 and 16 X 10(-6) M simultaneously changed the cell shape and reduced both the cellular content of adenine nucleotides and the relative level of ATP. In cells treated with 16 X 10(-6) M MeHg, a cellular increase in inosine and hypoxanthine and an unaltered content of adenine nucleotides in the nutrition medium, points to an intracellular degradation of adenine nucleotides. Incubation with 8 X 10(-6) M MeHg during the first hour of incubation, did not change the content of adenine nucleotides, however, MeHg induced a slowly progressing degeneration of cellular extensions. 3 X 10(-6) M Et3Pb induced morphological alterations but no changes in cellular nucleotide levels. The results show that morphological alterations occur in MeHg and Et3Pb treated cultures at concentrations of the compounds which are too low to change the content and composition of cellular adenine nucleotides.

Adenine Nucleotides↗
PubMed1977

Developmental-stage-dependent adenine transport in Neurospora crassa.

Although germinated conidia of Neurospora crassa transport adenine through two different systems, only one of these, namely, the general purine transport system, which transports adenine, hypoxanthine, guanine, and 6-methylpurine, is present in freshly harvested conidia of the wild type. The second system develops during germination. The latter system can transport adenine and 6-methylpurine. Time course and kinetic studies of adenine transport in freshly harvested conidia of an ad-8 mutant indicated that, in contrast to the wild type, the general purine transport activity is very low in this strain and that the second adenine transport system is possibly present in the ungerminated conidia. A study of adenine and hypoxanthine uptake in ad-8 and ad-4 mutants, both of which cannot utilize hypoxanthine for growth, isolated that the two transport systems may be under different metabolic controls.

Adenine↗
PubMed1990

Intermittent ischemia produces a cumulative depletion of mitochondrial adenine nucleotides in the isolated perfused rat heart.

The purpose of the present study was to determine if repetitive myocardial ischemia would result in the cumulative loss of mitochondrial adenine nucleotides. Isolated perfused rat hearts were subjected to continuous or intermittent ischemia. A single 5-minute period of continuous ischemia did not result in a significant decrease in the mitochondrial adenine nucleotide pool; a single 10-minute period of ischemia resulted in a decrease of approximately 17%. Next, the adenine nucleotide content of mitochondria from preischemic and 30-minute continuous ischemic hearts was compared with two groups of hearts undergoing intermittent ischemia (both groups receiving a total of 30 minutes of ischemia). One group received three 10-minute episodes of ischemia interrupted by 5-minute periods of reperfusion (3 x 10-minute intermittent ischemia); the other intermittent ischemic group received six 5-minute episodes of ischemia interrupted by 5-minute periods of perfusion (6 x 5-minute intermittent ischemia). The mitochondrial adenine nucleotide content (expressed as nanomoles per nanomole cytochrome a) for the preischemic and 30-minute continuous ischemic hearts was 14.7 +/- 0.6 and 8.0 +/- 0.4, respectively. The mitochondrial adenine nucleotide content of the 3 x 10-minute intermittent ischemia group (8.5 +/- 0.5) was not significantly different from the 30-minute continuous ischemic group. The mitochondrial adenine nucleotide content of the 6 x 5-minute intermittent ischemia group (11.0 +/- 0.6) was significantly larger than that of the 30-minute continuous and the 3 x 10-minute intermittent ischemia groups (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗