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)

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 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.

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.

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.

Release of sarcoplasmic enzymes from frog skeletal muscle

1981 ◽  
Vol 241 (3) ◽  
pp. C98-C105 ◽  
Author(s):  
G. Suarez-Kurtz ◽  
A. B. Eastwood
Keyword(s):  
Skeletal Muscle ◽  
Creatine Kinase ◽  
Lactate Dehydrogenase ◽  
Enzyme Release ◽  
Frog Skeletal Muscle ◽  
Free Medium ◽  
Release Rates ◽  
Brij 58 ◽  
Order Of Magnitude ◽  
Detergent Treatment

Isolated, intact frog muscles bathed in control saline release creatine kinase (CK) and lactate dehydrogenase (LDH) at constant rates for several hours. The basal rates of release from “toe” muscles (CK 0.087%/min; LDH 0.105%/min) were one order of magnitude greater than those from semitendinosus muscles. This is attributed to differences in muscle mass and geometry, and to the smaller diameter of toe muscle fibers. Enzyme release rates were not affected by Na-free or Cl-free solutions, whereas LDH release rate doubled during exposure to Ca-free (EGTA-containing) saline or in the presence of isosmotic solutions containing 120 mM KCl or potassium propionate. Following mechanical injury or detergent treatment (Brij 58), the enzyme release rates into Ca-free medium reached peak values 4 and 16 times (toe muscle), and 16 and 20–30 times (semitendinosus), respectively, the control rates. The greater effect of detergent treatment is ascribed to a larger area of sarcolemmal damage plus possible changes in the state of the enzymes in the sarcoplasm.

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.

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