Properties of the inorganic orthophosphate-adenosine triphosphate and adenosine diphosphate-adenosine triphosphate exchange reactions of digitonin particles.
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Adenine Nucleotides↗
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The action of oligomycin on the inorganic orthophosphate-adenosine triphosphate and adenosine diphosphate-adenosine triphosphate exchange reactions of digitonin particles.
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Adenine Nucleotides↗
The role of adenosine triphosphate and adenosine triphosphatase in the release of catecholamines from the adrenal medulla. 3. Similarities between the effects of adenosine triphosphate on chromaffin granules and on mitochondria.
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Adenosine Triphosphatases↗
The role of adenosine triphosphate and adenosine triphosphatase in the release of catecholamines from the adrenal medulla. IV. Adenosine triphosphate-- activated uptake of calcium by microsomes and mitochondria.
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Adenosine Triphosphatases↗
Adenosine triphosphate and adenosine triphosphatase in hormone-containing granules of posterior pituitary gland.
Neurosecretory granules prepared from bovine posterior pituitary glands by cell fractionation methods contain adenosine triphosphate and adenosine triphosphatase activity. Addition of adenosine triphosphate to suspensions of granules stimulates release of vasopressin. It is suggested that adenosine triphosphate and adenosine triphosphatase participate in the storage and release of vasopressin.
Adenosine Triphosphatases↗
Characteristics of analgesia induced by adenosine triphosphate.
Adenosine triphosphate (ATP) injected intravenously in mice was found to have dose-dependent analgesic activity in the hot plate and phenylquinone-induced stretching assays. ATP prolonged the hot plate latency (ED50 value of 1 (0.7-1.4) mg/kg) and inhibited phenylquinone-induced writhing (ED50 value of 0.4 (0.31-0.52) mg/kg). Low doses of ATP produced a potent antinociceptive effect without any significant depression of locomotor activity. Treatment of mice for either 4 days or 14 days with ATP did not result in development of physical dependence on or tolerance to ATP. The analgesic action of ATP was not antagonized by naloxone at 1 and 5 mg/kg. ATP analgesia was antagonized, in a dose-related fashion, by Ca++ ion injected intracerbroventricularly which may indicate that Ca++ plays a role in ATP-induced antinociception.
Adenosine Triphosphate↗
Myocardial hemodynamics during induced hypotension: a comparison between sodium nitroprusside and adenosine triphosphate.
Adenosine triphosphate (ATP) has been reported to be a hypotensive agent similar in effect to sodium nitroprusside (SNP). The purpose of this study was to examine and compare the effects of both SNP and ATP on general coronary hemodynamics, myocardial O2 consumption, and circulating catecholamines. Twelve dogs were anesthetized with 1.0% halothane and given either SNP or ATP by controlled infusion to reduce their systemic blood pressure by 50% for a 2-h period followed by a (blood pressure) recovery period. The ATP-induced hypotension was rapid, easily controlled, not accompanied by tachyphylaxis over the 120 min studied, and resulted in an increase in coronary sinus blood flow (CSBF), which plateaued at 260% above control. The increase in CSBF was almost immediate and remained at this elevated level for the duration of the induced hypotension. During the ATP-induced hypotension, there was no change in heart rate or circulating catecholamines. A 60% reduction in myocardial O2 uptake was observed, presumably from the cardiac unloading. In contrast, SNP-induced hypotension required a marked increase in dose over time, did not significantly increase CSBF, did increase heart rate, and resulted in large increases in circulating plasma catecholamines. Neither agent affected cardiac output. ATP-induced hypotension resulted in no change in cardiac lactic acid uptake, while SNP caused lactic acid production, indicating possible cardiac ischemia or cyanide toxicity.
Adenosine Triphosphate↗
Adenosine triphosphate and adenosine: perspectives in the acute management of paroxysmal supraventricular tachycardia.
Adenosine triphosphate (ATP) and adenosine exert strong and transient depressant effects on the sinoatrial and atrioventricular (AV) nodes of the human heart. The AV nodal effects of these drugs explain their high efficacy in either terminating AV re-entrant supraventricular tachycardia or in slowing ventricular rate during atrial tachyarrhythmias. Their very short half-life enables repeated administration of increased doses without reaching toxic effects and explains the transient character of their frequent but benign side effects. These agents represent a good alternative to verapamil in the acute management of paroxysmal supraventricular tachycardia both in infants and adults.
Adenosine↗
Comparative electrophysiologic effects of adenosine triphosphate and adenosine in the canine heart: influence of atropine, propranolol, vagotomy, dipyridamole and aminophylline.
The electrophysiologic effects of adenosine triphosphate (ATP) and adenosine and the modification of these effects by atropine, propranolol, vagotomy, dipyridamole and aminophylline were studied in a canine model. Both ATP and adenosine exerted transient, dose-dependent negative chronotropic and dromotropic effects on the sinoatrial and atrioventricular nodes, respectively. At all doses tested, the effects of ATP were more pronounced. Treatment with either atropine or propranolol plus bilateral cervical vagotomy attenuated the effects of ATP but not of adenosine. In the presence of propranolol plus vagotomy, both the negative chronotropic and dromotropic effects of ATP and adenosine were enhanced and attenuated in a similar manner by dipyridamole and aminophylline. Thus, when ATP and adenosine are injected rapidly into the right atrium of the intact canine heart, vagal involvement in the mechanism of action of ATP but not of adenosine is mainly responsible for the difference in the magnitude of the electrophysiologic effects of these 2 compounds, and only a small part of the electrophysiologic effects of ATP are the result of its degradation to adenosine.
Adenosine↗
On-line monitoring of enzymatic conversion of adenosine triphosphate to adenosine diphosphate by micellar electrokinetic chromatography.
Capillary electrophoresis can be a valuable tool for the on-line monitoring of bioprocesses. The enzymatic conversion of nucleotide adenosine triphosphate (ATP) to adenosine diphosphate (ADP) by hexokinase (HK) was monitored in the bioreactor interfaced by a laboratory-built microsampler to a capillary electrophoresis unit. The use of this specially designed sampling device enabled rapid consecutive injections to be performed without high-voltage (HV) interruptions. No additional sample preparation was required. The method of micellar electrokinetic chromatography, employing reversed electroosmotic flow (EOF) by cationic surfactant and reversed polarity mode provided a good resolution and short analysis time of less than 5 min. The samples were injected electrokinetically, using -25 kV voltage for 3 s and detected by their UV absorbance at 254 nm. The analytes were detected at a microg/ml level with a reproducibility of about 7%. To demonstrate the potential of CE in understanding the processes of biological interest, such as nucleotide degradation and metabolism, the investigation of the efficiency and the time course of the enzymatic transformation was carried out.
Adenosine Diphosphate↗
Electrophysiologic effects of adenosine triphosphate and adenosine on the mammalian heart: clinical and experimental aspects.
Adenosine triphosphate (ATP) and adenosine have strong negative chronotropic and dromotropic effects on the mammalian heart. The sensitivity of the sinus node and the atrioventricular node to ATP and adenosine manifests pronounced variability among species. For more than three decades, ATP has been used routinely in Europe in the acute therapy of paroxysmal supraventricular tachycardia. Preliminary clinical trials with adenosine in the United States suggest that this compound may have a similar therapeutic value. The exact mechanisms of action of ATP and adenosine on the mammalian heart are still not fully known. However, the vast clinical experience indicates that ATP, and probably also adenosine, can be safely and repetitively used in the acute therapy of paroxysmal supraventricular tachycardia.
Adenosine↗
The effects of adenosine triphosphate and adenosine diphosphate on transmission at the rat and frog neuromuscular junctions.
1 The effects of adenosine triphosphate (ATP) and adenosine diphosphate (ADP) were investigated on evoked end-plate potentials (e.p.ps) and on miniature end-plate potentials (min. e.p.ps) recorded from muscle fibres of the rat diaphragm and the frog sartorius.2 ATP and ADP decreased the quantum content of the e.p.ps and the frequency of the min. e.p.ps. The maximum effects produced by the two substances were similar.3 The potency of ATP was found to be similar to that of adenosine. In the presence of adenosine, in a concentration producing its maximum effect, the addition of ATP had no further effect. This is compatible with the idea that ATP acts in the same way as adenosine.
Adenosine↗
Adenosine triphosphate and adenosine diphosphate in human semen: correlation with sperm count and motility.
Adenosine triphosphate (ATP) and adenosine diphosphate (ADP) have been correlated with traditional semen parameters such as forward motility and sperm count. ATP and ADP were determined by a bioluminescence assay using the luciferin-luciferase reaction. Short boiling of the ejaculate was performed to inactivate phosphatases (ATPases) in the seminal plasma and the sperm tails. Fresh and deep-frozen semen samples from 45 men with oligozoospermia (n = 22) and normal sperm count (n = 23) were evaluated. Freezing of the sperm for 12 weeks did not effect the ATP or ADP content in the spermatozoa as compared to fresh semen. ATP and ADP concentration was in the range of picomoles/microliter and showed a significant correlation with the number of normal sperm per milliliter and a less marked correlation with the sperm motility. ATP and ADP concentration in the spermatozoa can be measured relatively easy and is reproducible. Unlike the monotonous evaluation of sperm motility by a technician, this biochemical method provides an objective parameter for semen quality. These qualities suggest that this method could be a way to determine the fertilizing potential of semen and to relate this to actual pregnancy rates.
Adenosine Diphosphate↗
Electrophysiological effect of adenosine triphosphate and adenosine on atrial and ventricular action potential duration in humans.
Bolus injection of adenosine triphosphate (ATP) or adenosine is widely used clinically for terminating supraventricular tachycardia. However, bolus injection of these drugs has been reported to provoke atrial fibrillation (Afib). The effects of ATP and adenosine on the monophasic action potential duration (MAPD) of atrial and ventricular muscle was investigated, as well as the changes in the spatial distribution of atrial functional refractoriness caused by adenosine. Bolus injection of ATP and adenosine shortened atrial MAPD; no change was observed in the ventricle. Because local f-f intervals during atrial fibrillation correlate with the atrial refractory period, changes in mean f-f intervals in the right atrial appendage, His bundle region, coronary sinus ostium and distal coronary sinus were compared before and after injection of adenosine during induced Afib. Maximal shortening of f-f intervals was observed in the right atrial appendage. Inhomogeneous shortening of atrial refractoriness may account for the Afib following bolus injection of ATP or adenosine.
Action Potentials↗
Disorder induced in nonoverlap myosin cross-bridges by loss of adenosine triphosphate.
Adenosine triphosphate-dependent changes in myosin filament structure have been directly observed in whole muscle by electron microscopy of thin sections of rapidly frozen, demembranated frog sartorius specimens. In the presence of ATP the thick filaments show an ordered, helical array of cross-bridges except in the bare zone. In the absence of ATP they show two distinct appearances: in the region of overlap with actin, there is an ordered, rigorlike array of cross-bridges between the thick and thin filaments, whereas in the nonoverlap region (H-zone) the myosin heads move away from the thick filament backbone and lose their helical order. This result suggests that the presence of ATP is necessary for maintenance of the helical array of cross-bridges characteristic of the relaxed state. The primary effect of ATP removal on the myosin heads appears to be weaken their binding to the thick filament backbone; released heads that are close to an actin filament subsequently form a new actin-based, ordered array.
Actins↗
A comparative study of the electrophysiologic effects of Striadyne, adenosine triphosphate and adenosine in the canine heart.
The chronotropic and dromotropic effects of the intra-atrial administration of 0.97, 1.93 and 2.90 microM/kg Striadyne, the pharmaceutical form of adenosine triphosphate (ATP) for clinical use, ATP, and adenosine, were compared in 13 anesthetized dogs. Striadyne, ATP and adenosine exerted transient dose-dependent negative chronotropic and dromotropic effects. There was no significant difference between the electrophysiologic effects of Striadyne and ATP which were significantly more pronounced than those of adenosine. Atropine (0.2 mg/kg) significantly attenuated the electrophysiologic effects of 2.90 microM/kg Stridyne and ATP but not those of adenosine. It is concluded that Striadyne and ATP have similar electrophysiologic effects which are more pronounced than those of adenosine mainly due to vagal involvement in their mechanism of action.
Adenosine↗
Uridine-5'-triphosphate and adenosine triphosphate gammaS induce mucin secretion via Ca2+-dependent pathways in human nasal epithelial cells.
OBJECTIVES: Nucleotides such as adenosine triphosphate (ATP) and uridine-5'-triphosphate (UTP) play fundamental roles in the early stage of secretion in nasal epithelial cells via the P2Y receptor. In this study, we examined the expression pattern of P2Y subtypes and their functions on Ca2+ influx ([Ca2+]i) in normal human nasal epithelial (NHNE) cells. We also examined the effect of UTP (an agonist for P2Y2) and ATPgammaS (an agonist for P2Y11) on mucin secretion and mucin gene expression. MATERIAL AND METHODS: The expression pattern of P2Y receptors and the mRNA levels of MUC5AC, MUC5B and MUC8 were examined after treatment with UTP and ATPgammaS by means of reverse transcriptase polymerase chain reaction. Mucin was quantified by an immunoblotting assay. We measured [Ca2+]i in NHNE cells using a double perfusion chamber. RESULTS: Two uracil-sensitive receptors (P2Y2, P2Y4) and two adenine-selective receptors (P2Y1, P2Y11) were expressed in NHNE cells. UTP and ATPgammaS increased [Ca2+]i via caffeine-sensitive pathways, and these two agonists stimulated mucin secretion to a similar magnitude without their gene enhancement. In addition, the mucin stimulatory effects subsided when the intracellular Ca2+ was removed by 2-bis-(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester. CONCLUSION: This study showed that P2Y2 and P2Y11 receptors were expressed in NHNE cells and that their agonists, UTP and ATPgammaS, act as secretogogues on mucin secretion via Ca2+-dependent pathways.
Adenosine Triphosphate↗
Effects of near-infra-red laser irradiation on adenosine triphosphate and adenosine diphosphate contents of rat brain tissue.
Low-power, near-infra-red laser irradiation has been used to relieve patients from various kinds of pain, though the precise mechanisms of such biological actions of the laser have not yet been resolved. To investigate the cellular mechanisms by near-infra-red laser on the nervous system, we examined the effect of 830-nm laser irradiation on the energy metabolism of the rat brain. The diode laser was applied for 15 min with an irradiance of 4.8 W/cm(2). Tissue adenosine triphosphate (ATP) content of the irradiated area in the cerebral cortex was 19% higher than that of the non-treated area, whereas the adenosine diphosphate (ADP) content showed no significant difference. Laser irradiation at another wavelength (652 nm) had no effect on either ATP or ADP contents. The temperature of the tissue was increased by 4.4-4.7 degrees C during the irradiation of both wavelengths. These results suggest that the increase in tissue ATP content did not result from the thermal effect, but from a specific effect of the laser operated at the 830-nm wavelength.
Adenosine Diphosphate↗