Serum requirement for release of heparin-induced lipase from perfused rat heart

1964 ◽  
Vol 206 (3) ◽  
pp. 610-614 ◽  
Author(s):  
M. F. Crass ◽  
H. C. Meng
Keyword(s):  
Rat Heart ◽  
Lipolytic Activity ◽  
Coconut Oil ◽  
Cottonseed Oil ◽  
Lipolytic Enzyme ◽  
Enzyme Release ◽  
Perfusion Medium ◽  
Bicarbonate Buffer ◽  
Oil Emulsion ◽  
Perfused Rat Heart

The release of a lipolytic enzyme from the isolated perfused rat heart was studied. The perfusion medium was a Krebs-Henseleit bicarbonate buffer, pH 7.4, with or without heparin and/or serum. The lipolytic activity of perfusates was determined by incubating the perfusate in a phosphate buffer, pH 7.4, at 37 C for 1 or 2 hr using coconut oil emulsion, rat chylomicrons, or cottonseed oil emulsion as a substrate in the presence of serum albumin. Both heparin and serum were required for optimal enzyme release; the optimal concentrations of heparin and serum were 50 µg/ml and 10% by volume, respectively. Addition of serum to the assay system could not replace its effect in the perfusion medium. The appearance of the enzyme in the perfusion medium was rapid; 55% of the total lipolytic activity was released within 2 min. The lipolytic activity of this enzyme was inhibited by protamine, NaCl, NaF, and taurocholate.

Energy dependence of enzyme release from hypoxic isolated perfused rat heart tissue

1988 ◽  
Vol 65 (4) ◽  
pp. 1855-1860 ◽  
Author(s):  
J. P. Kehrer ◽  
Y. Park ◽  
H. Sies
Keyword(s):  
Lactate Dehydrogenase ◽  
Rat Heart ◽  
Creatine Phosphate ◽  
Heart Tissue ◽  
Enzyme Release ◽  
Free Medium ◽  
Perfusion Medium ◽  
Perfused Rat Heart ◽  
Rat Hearts ◽  
Sudden Release

There is a sudden release of intracellular constituents upon reoxygenation of isolated perfused hypoxic heart tissue (O2 paradox) or on perfusion with calcium-free medium after a period of hypoxia. Rat hearts were perfused by the method of Langendorff (Pfluegers Arch. 61: 291-332, 1895) with Krebs-Henseleit medium containing 10 mM glucose. Hearts were equilibrated for 30 min, followed by 90 min of hypoxia or 60 min of hypoxia and 30 min of reoxygenation. The massive enzyme release observed upon reoxygenation after 60 min of hypoxia was prevented by infusing 0.5 or 5 mM cyanide 5 min before reoxygenation. Lactate dehydrogenase (LDH) release commenced immediately upon withdrawal of cyanide. Hearts perfused with calcium-free medium throughout hypoxia did not release increased amounts of LDH at reoxygenation. Perfusing heart tissue with medium containing 0 or 25 microM calcium, but not 0.25 or 2.5 mM, after 50 min of hypoxia initiated a release of cardiac LDH, which was not further enhanced by reoxygenation. Enzyme release was significantly inhibited when the calcium-free perfusion medium included 10 mM 2-deoxyglucose (replacing glucose), 0.5 mM dinitrophenol, or 2.5 mM cyanide. Histologically, hearts perfused with calcium-free medium after 50 min of hypoxia showed areas of severe necrosis and contracture without any evidence of the contraction bands that were seen in hearts reoxygenated in the presence of calcium. Cardiac ATP and creatine phosphate (PCr) levels were significantly decreased after 50-60 min of hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of cysteine on protein and coenzyme A synthesis in rat heart

1984 ◽  
Vol 247 (1) ◽  
pp. C99-C106 ◽  
Author(s):  
B. H. Chua ◽  
K. E. Giger ◽  
B. J. Kleinhans ◽  
J. D. Robishaw ◽  
H. E. Morgan
Keyword(s):  
Protein Synthesis ◽  
Rat Heart ◽  
Coenzyme A ◽  
Pantothenic Acid ◽  
Fold Increase ◽  
Creatine Phosphate ◽  
Aortic Pressure ◽  
Protective Agent ◽  
Bicarbonate Buffer ◽  
Perfused Rat Heart

The effect of cysteine availability on protein and coenzyme A (CoA) synthesis in perfused rat heart was incompletely evaluated in earlier experiments because rapid conversion of cysteine to cystine occurred when the perfusion buffer was oxygenated. This conversion was minimized by addition of an excess of reducing agents such as dithiothreitol or mercaptodextran or by provision of bathocuproine disulfonate, a copper chelator. Dithiothreitol was not a suitable protective agent because it reduced ATP and creatine phosphate contents. Perfusion of hearts with [35S]cystine or [35S]cysteine in the presence of mercaptodextran resulted in a 22-fold or 5-fold increase, respectively, in incorporation of [35S] into protein and a 5-fold or 8-fold increase, respectively, in incorporation into CoA compared with hearts supplied [35S]cystine or [35S]cysteine without the reducing agent. When compared with hearts perfused at an aortic pressure of 90 mmHg with bicarbonate buffer that contained 15 mM glucose, 25 mU insulin/ml, 0.4 mM [14C]phenylalanine, no cysteine and plasma levels of other amino acids, provision of 0.09 or 0.2 mM cysteine alone or in the presence of mercaptodextran, or bathocuproine disulfonate enhanced rates of protein synthesis 16-35%. When 0.2 mM cysteine was added to bicarbonate buffer containing 7 microM pantothenic acid, supplementation with mercaptodextran or bathocuproine disulfonate was required to raise CoA content. These results indicated that an exogenous supply of cysteine was needed to maintain maximal rates of protein and CoA synthesis in the perfused rat heart. Protective compounds were required to obtain the cysteine effect on CoA but not on protein synthesis.

scholarly journals Accumulation of amino acids in muscle of perfused rat heart. Effect of insulin

1965 ◽  
Vol 97 (1) ◽  
pp. 257-271 ◽  
Author(s):  
R Scharff ◽  
IG Wool
Keyword(s):  
Amino Acids ◽  
Heart Muscle ◽  
Rat Heart ◽  
Isobutyric Acid ◽  
Intracellular Water ◽  
Intracellular Concentration ◽  
Bicarbonate Buffer ◽  
Perfused Rat Heart ◽  
Actual Concentration ◽  
Net Uptake

1. Rat heart perfused with Krebs-Henseleit bicarbonate buffer released material containing ninhydrin-positive nitrogen, but the amount was less than that reported to be released by diaphragm; glucose, but not insulin, decreased the release of ninhydrin-positive nitrogen and increased the concentration of the same material in the intracellular water of heart. 2. When heart was perfused with a mixture of amino acids and glucose, there was actually a net uptake, and an increase in intracellular concentration, of ninhydrin-positive nitrogen. Changes in the concentration of ninhydrin-positive nitrogen did not accurately reflect changes in concentration of amino acids. 3. The effect of insulin on the actual concentration of individual amino acids in heart muscle was examined by perfusing the heart with a mixture of amino acids and other ninhydrin-positive substances in the same concentration as they are found in plasma. 4. The effect of insulin on the concentrations of amino acids in the medium and in the intracellular water of the heart was determined after perfusion for different periods of time. No clear or meaningful effect of insulin was observed, despite the fact that insulin significantly increased the accumulation, in each of the same hearts, of radioactivity from amino[(14)C]isobutyric acid.

scholarly journals The activation of pyruvate dehydrogenase in the perfused rat heart by adrenaline and other inotropic agents

1981 ◽  
Vol 194 (2) ◽  
pp. 639-643 ◽  
Author(s):  
J G McCormack ◽  
R M Denton
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Oxidative Metabolism ◽  
Rat Heart ◽  
Fold Increase ◽  
Diabetic Rats ◽  
Inotropic Agents ◽  
Perfusion Medium ◽  
Perfused Rat Heart ◽  
Phosphorylated Form

Adrenaline resulted in a reversible 4-fold increase in the amount of pyruvate dehydrogenase in its active non-phosphorylated form in the perfused rat heart within 1 min. The increase was less in extent in hearts from starved or diabetic rats or in hearts from control rats oxidizing acetate, unless pyruvate was added to the perfusion medium. Increases could also be induced by other inotropic agents, supporting the hypothesis that increases in cytoplasmic Ca2+ can be relayed into mitochondria and influence oxidative metabolism.

scholarly journals Rapid effects of isoprenaline, glucagon, pacing and potassium arrest on post-heparin lipoprotein lipase activity in the perfused rat heart

1979 ◽  
Vol 182 (1) ◽  
pp. 253-255 ◽  
Author(s):  
J Simpson
Keyword(s):  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Rat Heart ◽  
Lipoprotein Lipase Activity ◽  
Perfusion Medium ◽  
Perfused Rat Heart ◽  
Rat Hearts ◽  
Isolated Rat

The amount of lipoprotein lipase activity released by heparin into the perfusion medium of isolated rat hearts could be increased within 60s by isoprenaline, glucagon or pacing. Potassium arrest and propranolol inhibited the effects of isoprenaline and pacing respectively.

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