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PubMed1989

Determination of adenosine triphosphate in human semen to estimate the fertilizing potential and to quantify sperm antibodies.

The measurement of the ATP content of fresh semen is as accurate as the estimation of sperm motility by conventional methods in discriminating between semen of fertile versus subfertile men. The ATP content of frozen thawed donor semen is correlated with the probability of conception per cycle of insemination. Exact quantification of cytotoxic sperm antibodies in serum is possible with the adenosine-triphosphate-release-cytotoxicity test, since measurement is free of the bias of microscopic examination. The procedure has been simplified by testing only one serum dilution and calculating the 'sperm toxicity index'.

Adenosine Triphosphate↗
PubMed1972

An estimate of adenosine triphosphate release into the venous effluent from exercising human forearm muscle.

1. Human subjects performed a sustained contraction of the forearm muscles for 4 min in the presence of arterial and venous occlusion.2. The contraction was maintained at 5% of the maximum voluntary contraction, a tension during which the muscle blood flow might be expected to increase by about three times (Lind & McNicol, 1967).3. Adenosine triphosphate (ATP) was identified in the venous effluent from occluded exercising forearm, but not in the venous effluent from occluded forearm without exercise.4. The rate of degradation of ATP was assessed in plasma at 37 degrees C, with an estimate of the percentage loss occurring between sampling and testing. This enabled the rate of appearance of ATP in the blood at the time of exercise to be calculated as approximately 7.5-10.5 mug/min (14-20 n-mole/min). These amounts are compared with 16 mug/min that was infused intra-arterially into human forearm to cause a threefold increase in blood flow (Duff, Patterson & Shepherd, 1954).5. It is likely that the ATP detected in the venous effluent has active muscle as the source; if so, then the amounts calculated to be released could satisfy the vasodilator requirements of active skeletal muscle.6. The effects of circulating ATP on respiration and coronary blood flow during exercise is discussed, including the role it may play locally in the production of ischaemic pain.

Adenosine Triphosphate↗
PubMed1995

Firefly luciferase assay of adenosine triphosphate as a tool of quantitation of the viability of BCG vaccines.

The purpose of the present study was to compare conventional colony forming unit (CFU) enumeration with a bioluminescent measurement in order to quantitate living bacteria in BCG vaccine. Forty batches of BCG vaccine quantitated with respect to weight (10 each of concentration 120 mg/vial, 30 mg/vial, 1.5 mg/vial and 0.75 mg/vial, respectively) were tested. Adenosine triphosphate (ATP) was extracted using the boiling Tris-EDTA extraction method preceded by treatment with the ATP-hydrolysing enzyme apyrase, and the liberated ATP was assayed using a LKB 1251 luminometer. The sensitivity of the assay was 10(-11) M ATP which corresponded to 5 x 10(5) CFU/ml. A proportional relation between CFU and ATP content per vial was found up to 30 mg/vial, but for 120 mg/vial the CFU method seemed unreliable in contrast to the bioluminescence method. The measurements error for the logarithm (base 10) of ATP was 0.051 and this method was therefore more exact than the CFU method (0.097). Because the bioluminescence method is sensitive, reliable, time-saving and less expensive it seems preferable to CFU enumeration in the quality control of BCG vaccines.

Adenosine Triphosphate↗
PubMed1995

Role of extracellular adenosine triphosphate in the cytotoxic T-lymphocyte-mediated lysis of antigen presenting cells.

The lysis of antigen presenting cells (APCs) by cytotoxic T lymphocytes (CTLs) may be one mechanism whereby an immune response is downregulated by Staphylococcus superantigens. Disappearance of monocytes/macrophages from staphylococcal enterotoxin A (SEA)-activated peripheral blood mononuclear cell (PBMC) cultures, but not from control PBMC cultures was seen by flow cytometry. Recently, adenosine triphosphate (ATP) has been described as an effector molecule in CTL-mediated lysis of some murine tumor target cells. We have also shown that ATP caused the lysis of human macrophages, and that treatment of cells with interferon gamma (IFN gamma) rendered macrophages significantly more sensitive to ATP than untreated cells. To show that this purine nucleotide may play a role in modulating the immune system, we generated human CTLs that were stimulated with SEA, and used them as effector cells against SEA-pulsed autologous macrophages. CTLs were found to specifically lyse SEA-pulsed macrophages, while control, unpulsed, macrophages were unaffected. The addition of hexokinase, an enzyme that hydrolyzes ATP, significantly abrogated the killing of SEA-pulsed cells during the assay. In examining the mechanism of cytotoxicity, electron microscopy showed that macrophages incubated with both ATP and CTLs underwent necrosis, rather than apoptosis. From these results, it is suggested that ATP is released from CTLs during antigen presentation, and that IFN gamma-activated macrophages, which are inherently more sensitive to this mediator, are readily lysed and therefore removed from circulation, thus downregulating an immune response.

Adenosine Triphosphate↗
PubMed1994

Adenosine triphosphate bioluminescence as a method to determine microbial levels in scald and chill tanks at a poultry abattoir.

According to Hazard Analysis of Critical Control Points (HACCP) programs developed for the poultry industry, poultry processing waters should be actively monitored to minimize cross-contamination between chicken carcasses. In order to monitor HACCP programs, a test is required that provides results on a real time basis. A modified adenosine triphosphate (ATP) bioluminescence test has been developed that can assess microbial levels in poultry processing waters within 15 min. A study was conducted to determine the effectiveness of this test for examining scald, prechill, and chill tank waters. The results showed that the modified ATP bioluminescence method gave results comparable to plate counts. The microbial levels were dependent on the tank and the time of sampling. The highest microbial levels were detected in the scald tank. In all three tanks, the microbial levels increased over time during the day.

Abattoirs↗
PubMed2003

Synergistic activation of mitogen-activated protein kinase by insulin and adenosine triphosphate in liver cells: permissive role of Ca2+.

We have previously demonstrated that insulin and G(q)-coupled receptor agonists individually activate mitogen-activated protein kinase (MAPK) in liver cells and both effects involve an influx of extracellular Ca(2+). Yet, these agonists have opposing physiological actions on hepatocyte glucose metabolism. We thus investigated the interaction between insulin and the P2Y(2) purinergic agonist adenosine triphosphate (ATP) on MAPK in HTC cells, a model hepatocyte cell line, and determined the involvement of cytosolic Ca(2+). Insulin and ATP each induced a dose-dependent phosphorylation of p44/42 MAPK that was partially inhibited by EGTA. However, pretreatment with insulin markedly increased the MAPK phosphorylation response to ATP. This potentiation was canceled by chelation of extracellular Ca(2+) with EGTA. We used patch clamp electrophysiology and fluorescence microscopy to understand the role of intracellular Ca(2+) in this effect. Insulin and ATP, respectively, induced monophasic and multiphasic changes in membrane potential and intracellular Ca(2+) as expected. Pretreatment with 10 nmol/L insulin significantly decreased the initial rapid depolarization (inward nonselective cation current [NSCC]), as well as the compounded Ca(2+) response induced by 100 micro mol/L ATP. However, in Ca(2+)-free conditions, insulin did not modify the Ca(2+) mobilized from internal pools after stimulation with ATP. Upon Ca(2+) readmission, internal store depletion by ATP or thapsigargin doubled the rate of capacitative Ca(2+) influx, whereas insulin increased this influx 1.32-fold. On the other hand, insulin pretreatment counteracted the increased rate of Ca(2+) influx induced by ATP but not by thapsigargin. In summary, insulin counteracts the membrane potential and Ca(2+) responses to ATP in HTC cells. However, insulin and ATP effects on MAPK activation are synergistic and Ca(2+) influx plays a permissive role. Therefore, the opposing metabolic actions of insulin and G(q)-coupled receptor agonists involve an interaction in signaling pathways that resides downstream of Ca(2+) influx.

Adenosine Triphosphate↗
PubMed1992

Effects of prostaglandin E1 on left ventricular performance in dogs; comparisons with trinitroglycerin and adenosine triphosphate.

To examine the cardiovascular response to prostaglandin E1 infusion, we observed hemodynamic changes including left ventricular diameter (an ultrasonic crystal pair) during PGE(1)-induced hypotension in anesthetized open-chest dogs. Left ventricular contractility was assessed primarily by measuring the slope of the left ventricular endsystolic pressure-diameter relation (ESPDR) determined by combining end-systolic points from a vena caval occlusion. The cardiovascular effects of induced hypotension by infusions of trinitroglycerin and adenosine triphosphate were also examined at the equivalent magnitude of hypotension. Approximately 25% reduction of systemic blood pressure was produced by the three agents. PGE(1) significantly increased cardiac output from 1200 +/- 132 to 1439 +/- 162 ml.min(-1) (mean +/- SE, P < 0.05), stroke volume from 9.1 +/- 1.1 to 10.0 +/- 1.0 ml (P < 0.05), and %-diameter shortening from 10.4 +/- 0.8 to 14.4 +/- 0.8% ( P < 0.01), but the slope of ESPDR was unchanged. Similar changes were also observed during adenosine triphosphate-induced hypotension. PGE(1) significantly decreased end-diastolic diameter in a similar manner to trinitroglycerin. Thus PGE(1) appears to have little influence on left ventricular contractility aside from its effects on afterload and preload, indicating that it is a useful agent for producing controlled hypotension during anesthesia.

Journal Article↗
PubMed1991

Ca2(+)-activated K+ channels in airway smooth muscle are inhibited by cytoplasmic adenosine triphosphate.

Large-conductance Ca2(+)-activated K+ channels were studied in membranes of cultured rabbit airway smooth muscle cells, using the patch-clamp technique. In cell-attached recordings, channel openings were rare and occurred only at very positive potentials. Bradykinin (10 microM), an agonist which releases Ca2+ from the sarcoplasmic reticulum, transiently increased channel activity. The metabolic blocker 2,4-dinitrophenol (20 microM), which lowers cellular adenosine triphosphate (ATP) levels, induced a sustained increase of channel activity in cell-attached patches. In excised patches, these channels had a slope conductance of 155 pS at 0 mV, were activated by depolarization and by increasing the Ca2+ concentration at the cytoplasmic side above 10(-7) mol/l. ATP, applied to the cytoplasmic side of the patches, dose-dependently decreased the channel's open-state probability. An inhibition constant (Ki) of 0.2 mmol/l was found for the ATP-induced inhibition. ATP reduced the Ca2+ sensitivity of the channel, shifting the Ca2+ activation curve to the right and additionally reducing its steepness. Our results demonstrate that cytoplasmic ATP inhibits a large-conductance Ca2(+)-activated K+ channel in airway smooth muscle. This ATP modulation of Ca2(+)-activated K+ channels might serve as an important mechanism linking energy status and the contractile state of the cells.

Adenosine Triphosphate↗
PubMed2002

Adenosine triphosphate release and purinergic regulation of cholangiocyte transport.

The discovery of purinergic receptors on almost every cell type studied to date suggests that purinergic signaling is a fundamental process regulating cell and organ level functions. Purinergic receptors have been found on all principal liver cell types, including liver parenchymal cells, or hepatocytes, and biliary epithelial cells, or cholangiocytes. Both hepatocytes and cholangiocytes are capable of the regulated release of adenosine triphosphate (ATP), and both cell types express a range of purinergic receptors to mediate cellular processes. The role of extracellular nucleotides in liver function is presently being elucidated. Extracellular ATP, in addition to autocrine regulation of liver cell volume, has recently been shown to play an important role in paracrine signaling to coordinate specific hepatocyte and cholangiocyte cellular responses. The findings that (1) cholangiocytes are capable of the regulated release of ATP into bile, (2) ATP is present in bile in concentrations capable of stimulating purinergic receptors, and (3) P2 receptor stimulation results in brisk Cl(-) channel activation and fluid secretion suggest an important role of extracellular ATP in the regulation of bile formation. This article highlights important developments in our understanding of the role of purinergic signaling in cholangiocyte transport and bile formation.

ATP-Binding Cassette Transporters↗
PubMed1998

Endothelium-released adenosine triphosphate contributes to vasoconstrictor responses to periarterial nerve stimulation in isolated, perfused canine splenic arteries.

P2X-Purinoceptors and alpha1-adrenoceptors have previously been shown to be involved in double-peaked vasoconstrictor responses to periarterial electrical nerve stimulation in the isolated and perfused canine splenic artery. The present study was designed to investigate the influence of endothelium removal on vasoconstrictor responses to periarterial nerve stimulation, tyramine, noradrenaline, and adenosine triphosphate (ATP) in the isolated canine splenic artery. Intraluminal administration of saponin completely abolished the acetylcholine-induced vasodilatation and potentiated the vasoconstrictor response to KCl. Double-peaked vasoconstriction (two phases of vasoconstriction) was readily induced by periarterial electrical nerve stimulation in the canine splenic arterial preparation with or without endothelium and was consistently abolished by treatment with tetrodotoxin. Removal of endothelium slightly but significantly decreased the first-phase vasoconstrictor responses to stimulation of 1 or 10 Hz, and did not affect the second-phase. The vasoconstrictor responses to tyramine, noradrenaline, and ATP were not modified by endothelium removal. From these results, it is postulated that ATP released from endothelium, as a modulator of sympathetic nerve cotransmission, may partially contribute to the purinergic constriction component in the canine splenic artery.

Adenosine Triphosphate↗
PubMed1985

Erythrocyte filterability and adenosine triphosphate levels in normal pregnancy and puerperium.

The filterability of erythrocytes was determined by a filtration method using erythrocytes suspended either in phosphate-buffered saline or in native plasma. Erythrocytes from pregnant women in the second and third trimester were significantly less filterable than those from non-pregnant women. On 0 to 1 day after delivery, erythrocyte filterability was further reduced, being significantly lower than that in the third trimester of pregnancy. Erythrocyte adenosine triphosphate (ATP) levels during pregnancy were not significantly different but in early puerperal period it was significantly lower than that in non-pregnant women. One month after delivery the filterability and ATP content of erythrocytes returned to the non-pregnant levels. The size and hemoglobin concentration of erythrocytes were unchanged during pregnancy and puerperium.

Adenosine Triphosphate↗
PubMed2000

Adenosine triphosphate affects interleukin -1beta release by T98G glioblastoma cells through a purinoceptor-independent mechanism.

T98G glioblastoma cells were previously shown to significantly increase interleukin-1beta (IL-1beta) mRNA levels in response to IL-1beta stimulation. This work demonstrates that in such conditions T98G, despite possessing biologically active interleukin converting enzyme, do not release detectable amounts of IL-1beta, even in the presence of 20 mM adenosine triphosphate (ATP). IL-1beta secretion is observed only following concomitant stimulation with 1000 units/ml of IL-1beta and 20 mM ATP. ATP induces a dose-dependent depolarization of T98G plasma membrane, whereas it does not affect Ca(2+) concentration or cell membrane permeability. Our data, together with the observation that the depolarizing effects of ATP are retained after preincubation with 100 microM suramin, an antagonist of P2-purinoceptors, suggest that ATP plays a role in IL-1beta secretion by T98G but its effects do not occur through P2-purinoceptors.

Adenosine Triphosphate↗
PubMed1985

Adenosine triphosphate pyrophosphohydrolase and neutral inorganic pyrophosphatase in pathologic joint fluids. Elevated pyrophosphohydrolase in calcium pyrophosphate dihydrate crystal deposition disease.

Adenosine triphosphate pyrophosphohydrolase (ATPPPH) and neutral inorganic pyrophosphatase activities were assayed in synovial fluids (SF) from 37 patients with a variety of arthropathies. ATPPPH activity was detected in all fluids, but was highest in patients with chronic chondrocalcinosis; its activity in patients with osteoarthritis was higher than that in patients with rheumatoid arthritis, gout, or pseudogout. ATPPPH activity correlated positively with SF pyrophosphate concentration and negatively with SF white blood cell count. Pyrophosphatase activity did not correlate with diagnosis, pyrophosphate level, or white blood cell count.

Adenosine Triphosphatases↗
PubMed2003

Recognition of adenosine triphosphate binding sites using parallel cascade system identification.

Parallel cascade identification (PCI) is a method for approximating the behavior of a nonlinear system, from input/output training data, by constructing a parallel array of cascaded dynamic linear and static nonlinear elements. PCI has previously been shown to provide an effective means for classifying protein sequences into structure/function families. In the present study, PCI is used to distinguish proteins that are binding to adenosine triphosphate or guanine triphosphate molecules from those that are nonbinding. Classification accuracy of 87.1% using the hydrophobicity scale of Rose et al. (Hydrophobicity of amino acid residues in globular proteins. Science 229:834-838, 1985), and 88.8% using Korenberg's SARAH1 scale, are obtained, as measured by tenfold cross-validation testing. Nearest-neighbor and K-nearest-neighbor (KNN) classifiers are constructed, and the resulting accuracy is, respectively, 88.0% and 90.8% on the SARAH1-encoded test data set, as measured by the above testing protocol. Significantly improved classification accuracy is achieved by combining PCI and KNN classifiers using quadratic discriminant analysis: accuracy rises from 87.9% (PCI) and 87.4% (KNN) to 96.5% for the combination, as measured by twofold cross-validation testing on the SARAH1-encoded test data set.

Adenosine Triphosphate↗
PubMed2003

Reproducible induction of atrioventricular nodal reentrant tachycardia with adenosine triphosphate.

A 29-year-old woman was referred for electrophysiological testing and radiofrequency ablation because of repeated episodes of palpitation of a 8-year duration. The 12-lead ECG during palpitations showed narrow QRS tachycardia at a rate of 160 beats/min. Dual AVN physiology according to electrophysiological criteria was not shown by single atrial extrastimulation and the tachycardia could not be induced. Slow/fast atrioventricular nodal reentrant tachycardia (AVNRT) was induced once by double atrial extrastimuli, but it was not reproducible. However, intravenous bolus injection of adenosine triphosphate (12.5 mg) during sinus rhythm led to reproducible initiation of slow/fast AVNRT.

Adenosine Triphosphate↗