scholarly journals The discovery of a rapidly metabolized polymeric tetraphosphate derivative of adenosine in perfused rat heart

1984 ◽  
Vol 223 (3) ◽  
pp. 627-632 ◽  
Author(s):  
J Mowbray ◽  
W L Hutchinson ◽  
G R Tibbs ◽  
P G Morris
Keyword(s):  
Organic Acid ◽  
Rat Heart ◽  
Purine Nucleoside ◽  
Acid Phosphate ◽  
Perfused Rat Heart ◽  
Rat Hearts ◽  
Adenosine Phosphate ◽  
Perfused Rat Hearts ◽  
Radioactive Labelling

The predicted presence in perfused rat hearts of a rapidly metabolized but hitherto unrecognized form of adenosine phosphate has been confirmed by specific radioactive labelling. The properties of the purified compound suggest that it is a heteropolymer of a small organic acid, phosphate and purine nucleoside in the proportions 1:4:1.

scholarly journals The release of 3′:5′-cyclic monophosphate from the isolated perfused rat heart

1975 ◽  
Vol 152 (2) ◽  
pp. 429-432 ◽  
Author(s):  
John A. O'Brien ◽  
Richard C. Strange
Keyword(s):  
Cyclic Amp ◽  
Rat Heart ◽  
Perfused Rat Heart ◽  
Cyclic Monophosphate ◽  
Isolated Perfused Rat Heart ◽  
Rat Hearts ◽  
Basal Release ◽  
Perfused Rat Hearts ◽  
Isolated Perfused Rat Hearts

Although basal release of cyclic AMP from isolated perfused rat hearts was not measurable, isoprenaline induced substantial release of the nucleotide, suggesting that in vivo the myocardium can contribute to plasma cyclic AMP. Anoxia also increased the amount of cyclic AMP released, but insulin and nicotinate alone or in combination had no effect.

Preconditioning accelerates contracture and ATP depletion in blood-perfused rat hearts

1995 ◽  
Vol 269 (4) ◽  
pp. H1415-H1420 ◽  
Author(s):  
K. G. Kolocassides ◽  
M. Galinanes ◽  
D. J. Hearse
Keyword(s):  
Rat Heart ◽  
Contractile Function ◽  
Study Groups ◽  
Atp Depletion ◽  
Perfused Rat Heart ◽  
Ischemic Contracture ◽  
Isolated Hearts ◽  
Time To Peak ◽  
Rat Hearts ◽  
Perfused Rat Hearts

We investigated the effect of preconditioning on the ischemia-induced depletion of ATP in the blood-perfused rat heart. Isolated hearts (n = 5/group) were aerobically perfused with whole blood from a support rat and subjected to zero-flow global ischemia (37 degrees C) for periods up to 35 min. Frozen hearts were taken for metabolic analysis. Ischemic contracture was assessed with an isovolumic intraventricular balloon. The study groups were 1) control (C) with unprotected ischemia, 2) preconditioning (PC; 2 cycles of 3-min ischemia/3-min reperfusion), and 3) cardioplegia (CP; St. Thomas') before ischemia. Preconditioning accelerated, whereas cardioplegia delayed, ischemic contracture (time to peak contracture: PC = 8.1 +/- 0.3 and CP = 25.1 +/- 0.2 min vs. C = 15.6 +/- 0.3 min, P < 0.05). The ischemia-induced decline in ATP was delayed by cardioplegia but accelerated by preconditioning (P < 0.05). In a parallel study, preconditioning and cardioplegia protected postischemic contractile function to a similar extent. Thus, in the blood-perfused rat heart, preconditioning accelerated ischemic contracture and depletion of ATP. In contrast, cardioplegia slowed ischemic contracture and ATP depletion.

Heterogeneity of the hypoxic state in rat heart is determined at capillary level

1993 ◽  
Vol 264 (2) ◽  
pp. H294-H301 ◽  
Author(s):  
C. Ince ◽  
J. F. Ashruf ◽  
J. A. Avontuur ◽  
P. A. Wieringa ◽  
J. A. Spaan ◽  
...  
Keyword(s):  
Rat Heart ◽  
High Flow ◽  
Rat Hearts ◽  
Nadh Fluorescence ◽  
Perfused Rat Hearts ◽  
Hypoxic State ◽  
Microsphere Embolization

Heterogeneity in the hypoxic state of Tyrode-perfused rat hearts was studied using NADH and Pd-porphine videofluorometry. Ischemic as well as high-flow anoxia resulted in a homogeneous rise of tissue NADH fluorescence, whereas normoxic recovery from both types of anoxia caused transiently persisting patchy fluorescent areas. Patterns were always the same for a given heart. PO2 distribution in the vasculature measured by Pd-porphine phosphorescence showed patterns similar to the NADH fluorescence patterns. Microsphere embolization of the capillaries, but not of arterioles, elicited identical NADH fluorescence patterns as seen during recovery from anoxia without microspheres. High heartbeat rates also caused patchy fluorescent areas but not in the presence of adenosine. Patterns corresponded to those seen during normoxic recovery from anoxia under low beat rates. It is concluded that there are circulatory units in the rat heart at the capillary level that result in the temporary persistence of anoxic areas during recovery from anoxia. These vulnerable areas are the first to be compromised during high heartbeat rates.

scholarly journals The molecular structure of a rapidly formed oligomeric adenosine tetraphosphate derivative from rat heart

1986 ◽  
Vol 234 (3) ◽  
pp. 623-627 ◽  
Author(s):  
W L Hutchinson ◽  
P G Morris ◽  
J Mowbray
Keyword(s):  
Molecular Structure ◽  
Rat Heart ◽  
Chromatographic Analysis ◽  
Trichloroacetic Acid ◽  
Adenine Nucleotides ◽  
Specific Radioactivity ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Rapid Equilibrium

The inability to account for large systematic variations with time in soluble adenine nucleotides in perfused rat hearts [Bates, Perrett & Mowbray (1978) Biochem. J. 176, 485-493; Mowbray, Bates & Perrett (1981) FEBS Lett. 131, 55-59; Mowbray, Perrett & Bates (1984) Int. J. Biochem. 16, 889-894] led us to show that the soluble nucleotides are in rapid equilibrium with some hitherto unrecognized trichloroacetic acid/methanol-precipitable highly phosphorylated heteropolymeric form [Mowbray, Hutchinson, Tibbs & Morris (1984) Biochem. J. 223, 627-632]. Selective digestion coupled to chromatographic analysis together with m.s. and 31P-n.m.r. spectrometry have now been used to show that the likely structure for a purified oligomer that is in specific-radioactivity equilibrium with tissue ATP is 3-phospho-[glyceroyl-gamma-triphosphoroyl-5′-adenosine-3′-3- phospho]4 glyceroyl-gamma-triphosphoroyl-5′-adenosine.

Influence of stimulation frequency on [Na+]i and contractile function in Langendorff-perfused rat heart

1997 ◽  
Vol 273 (3) ◽  
pp. H1246-H1254 ◽  
Author(s):  
L. S. Maier ◽  
B. Pieske ◽  
D. G. Allen
Keyword(s):  
Rat Heart ◽  
Contractile Function ◽  
Stimulus Frequency ◽  
Calibration Procedure ◽  
Stimulation Frequency ◽  
Pressure Amplitude ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Frequency Relationship ◽  
Triton X

To study the relationship between stimulation frequency and intracellular Na+ concentration ([Na+]i), Langendorff-perfused rat hearts were loaded with the Na(+)-sensitive dye sodium-binding benzofuran isophthalate (SBFI). An intracellular calibration procedure allowed SBFI fluorescence to be transformed into [Na+]i. Compartmentation of SBFI was evaluated by permeabilizing sarcolemmal membranes with saponin and subcellular compartments with Triton X-100. Most of the indicator was located in the myoplasm (69%). When stimulation frequency was increased from 0 to 6 Hz, [Na+]i increased from 3.0 to 7.9 mM, whereas pressure amplitude (PA) declined to 49% of the maximum recorded at 2 Hz. Blocking sarcoplasmic reticulum (SR) Ca2+ uptake with 2,5-di(tert-butyl)-1,4-benzohydroquinone (TBQ; 10 microM) at 2 Hz increased [Na+]i from 4.9 to 8.4 mM and decreased PA by 70%. Raising stimulation frequency then resulted in a further increase in [Na+]i and decline in PA. In conclusion, these data indicate that the rat heart is characterized by a negative pressure-frequency relationship associated with increasing [Na+]i at higher heart rates. After inhibition of SR Ca2+ uptake, [Na+]i further increases, whereas PA declines with increasing stimulus frequency. It is suggested that part of the rise of [Na+]i with stimulus frequency and TBQ may be associated with increased Ca2+ extrusion and Na+ influx on the Na+/Ca2+ exchange system.

Normalization strategy is critical for the outcome of miRNA expression analyses in the rat heart

2011 ◽  
Vol 43 (10) ◽  
pp. 604-610 ◽  
Author(s):  
Trond Brattelid ◽  
Eva-Katrine Aarnes ◽  
Erik Helgeland ◽  
Steinar Guvaåg ◽  
Heike Eichele ◽  
...  
Keyword(s):  
Mirna Expression ◽  
Rat Heart ◽  
Ex Vivo ◽  
Rank Order ◽  
Free Water ◽  
Early Reperfusion ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Assay Protocol ◽  
4.5S Rna

Since normalization strategies plays a pivotal role for obtaining reliable results when performing quantitative PCR (qPCR) analyses, this study investigated several miRNA normalization candidates in regards to their efficiency as normalization standards in the ischemic reperfused ex vivo rat heart, with special reference to regulation of the miRNAs miR-1 and miR-101b. The possibility of including primers for several miRNAs in one reverse transcription (RT) reaction was also investigated. Langendorff perfused rat hearts were subjected to 30 min regional ischemia and 0, 1, 5, 15, or 120 min reperfusion. Total RNA was isolated and reverse transcribed for miRNA qPCR analysis. Normalization candidates were evaluated by the NormFinder and geNorm algorithms and the following stability expression rank order was obtained: sno202 < U6B < U87 < snoRNA < 4.5S RNA A < Y1 < 4.5S RNA B < GAPDH. Applying U6B as a normalizer it was found that miR-1 and miR-101b was downregulated in the ischemic reperfused myocardium. Furthermore, up to three primers could be included in one RT reaction by replacing RNase-free water with two supplemental sets of primers in the TaqMan MicroRNA assay protocol. This study demonstrates the importance of validating normalization standards when performing miRNA expression analyses by qPCR, and that miR-1 and miR-101b may play an important role during early reperfusion of the ischemic rat heart.

Metabolic inhibition in the perfused rat heart: evidence for glycolytic requirement for normal sodium homeostasis

1998 ◽  
Vol 274 (4) ◽  
pp. H1082-H1089 ◽  
Author(s):  
José Dizon ◽  
Daniel Burkhoff ◽  
Joseph Tauskela ◽  
John Whang ◽  
Paul Cannon ◽  
...  
Keyword(s):  
Oxidative Metabolism ◽  
Rat Heart ◽  
High Energy ◽  
Shift Reagent ◽  
Resonance Spectroscopy ◽  
High Energy Phosphate ◽  
Perfused Rat Heart ◽  
Rat Hearts ◽  
Rapid Pacing ◽  
Subcellular Compartmentalization

Subcellular compartmentalization of energy stores to support different myocardial processes has been exemplified by the glycolytic control of the ATP-sensitive K+ channel. Recent data suggest that the control of intracellular sodium (Nai) may also rely on glycolytically derived ATP; however, the degree of this dependence is unclear. To examine this question, isolated, perfused rat hearts were exposed to hypoxia, to selectively inhibit oxidative metabolism, or iodoacetate (IAA, 100 μmol/l), to selectively inhibit glycolysis. Nai and myocardial high-energy phosphate levels were monitored using triple-quantum-filtered (TQF)23Na and31P magnetic resonance spectroscopy, respectively. The effects of ion exchange mechanisms (Na+/Ca2+, Na+/H+) on Nai were examined by pharmacological manipulation of these channels. Nai, as monitored by shift reagent-aided TQF 23Na spectral amplitudes, increased by ∼220% relative to baseline after 45 min of perfusion with IAA, with or without rapid pacing. During hypoxia, Nai increased by ∼200% during rapid pacing but did not increase in unpaced hearts or when the Na+/H+exchange blocker ethylisopropylamiloride (EIPA, 10 μmol/l) was used. Neither EIPA nor a low-Ca2+perfusate (50 μmol/l) could prevent the rise in Nai during perfusion with IAA. Myocardial function and high-energy phosphate stores were preserved during inhibition of glycolysis with IAA and continued oxidative metabolism. These results suggest that glycolysis is required for normal Na+ homeostasis in the perfused rat heart, possibly because of preferential fueling of Na-K-adenosinetriphosphatase by glycolytically derived ATP.

scholarly journals The effects of glucose, acetate, lactate and insulin on protein degradation in the perfused rat heart

1982 ◽  
Vol 206 (3) ◽  
pp. 467-472 ◽  
Author(s):  
P H Sugden ◽  
D M Smith
Keyword(s):  
Protein Degradation ◽  
Rat Heart ◽  
Plasma Concentrations ◽  
Normal Range ◽  
Perfused Rat Heart ◽  
Rat Hearts ◽  
Insulin Inhibition

Rat hearts were perfused as working preparations by the method of Taegtmeyer, Hems & Krebs [(1980 Biochem. J. 186, 701-711]. In the presence of glucose, insulin significantly inhibited protein degradation at concentrations as low as 50 mu units/ml. Acetate or lactate, when present either as sole fuel for contraction or in combination with glucose, did not inhibit protein degradation. Insulin inhibition or protein degradation was decreased with either lactate as sole fuel. We suggest that the inhibition of protein degradation occurs over the normal range of plasma concentrations of insulin present in vivo and that the presence of glucose may be at least in part necessary for this effect of insulin.

scholarly journals Measurement of oxidized glutathione and total glutathione in the perfused rat heart

1970 ◽  
Vol 117 (4) ◽  
pp. 661-665 ◽  
Author(s):  
P. L. Wendell
Keyword(s):  
Glutathione Reductase ◽  
Rat Heart ◽  
Enzyme Reaction ◽  
Heart Tissue ◽  
Oxidized Glutathione ◽  
Total Glutathione ◽  
Perfused Rat Heart ◽  
Rat Hearts

1. A method was developed for the assay of GSSG in heart tissue. 2. GSSG and total glutathione were measured in rat hearts perfused under a variety of conditions. About 2% of the total glutathione is present as GSSG. The concentrations of GSSG and GSH remained constant under all the conditions tested. 3. These results are discussed with reference to the equilibrium and rate of the glutathione reductase reaction in the cell. It is concluded that the enzyme reaction does not lie near equilibrium.

scholarly journals Inhibition of LINE-1 expression in the heart decreases ischemic damage by activation of Akt/PKB signaling

2006 ◽  
Vol 25 (2) ◽  
pp. 314-324 ◽  
Author(s):  
Eliana Lucchinetti ◽  
Jianhua Feng ◽  
Rafaela da Silva ◽  
Genrich V. Tolstonog ◽  
Marcus C. Schaub ◽  
...  
Keyword(s):  
Infarct Size ◽  
Functional Recovery ◽  
Rat Heart ◽  
Cardiac Tissue ◽  
Ischemia Reperfusion ◽  
Myocardial Damage ◽  
Immunoblot Analysis ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Antisense Odns

Microarray analyses indicate that ischemic and pharmacological preconditioning suppress overexpression of the non-long terminal repeat retrotransposon long interspersed nuclear element 1 (LINE-1, L1) after ischemia-reperfusion in the rat heart. We tested whether L1 overexpression is mechanistically involved in postischemic myocardial damage. Isolated, perfused rat hearts were treated with antisense or scrambled oligonucleotides (ODNs) against L1 for 60 min and exposed to 40 min of ischemia followed by 60 min of reperfusion. Functional recovery and infarct size were measured. Effective nuclear uptake was determined by FITC-labeled ODNs, and downregulation of L1 transcription was confirmed by RT-PCR. Immunoblot analysis was used to assess changes in expression levels of the L1-encoded proteins ORF1p and ORF2p. Immunohistochemistry was performed to localize ORF1/2 proteins in cardiac tissue. Effects of ODNs on prosurvival protein kinase B (Akt/PKB) expression and activity were also determined. Antisense ODNs against L1 prevented L1 burst after ischemia-reperfusion. Inhibition of L1 increased Akt/PKBβ expression, enhanced phosphorylation of PKB at serine 473, and markedly improved postischemic functional recovery and decreased infarct size. Antisense ODN-mediated protection was abolished by LY-294002, confirming the involvement of the Akt/PKB survival pathway. ORF1p and ORF2p were found to be expressed in rat heart. ORF1p showed a predominantly nuclear localization in cardiomyocytes, whereas ORF2p was exclusively present in endothelial cells. ORF1p levels increased in response to ischemia, which was reversed by antisense ODN treatment. No significant changes in ORF2p were noted. Our results demonstrate that L1 suppression favorably affects postischemic outcome in the heart. Modifying transcriptional activity of L1 may represent a novel anti-ischemic therapeutic strategy.

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