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PubMed1983

Abnormal phosphocreatine metabolism in perfused diabetic hearts. A 31P nuclear-magnetic-resonance study.

31P n.m.r. analysis of control and diabetic hearts perfused for 1 h with a glucose buffer showed constant and normal levels of phosphocreatine and ATP. Supplementing the buffer with 0.5, 1.2 or 2.0 mM-palmitic acid had little or no effect on high-energy-phosphate levels in control hearts. In contrast, increases in palmitate concentration produced significant decreases in ATP in diabetic hearts, despite normal and constant levels of phosphocreatine. This 31P n.m.r. study suggests a defect in phosphocreatine metabolism in the perfused diabetic heart that might be related to creatine kinase kinetics.

Adenosine Triphosphate↗

PubMed1985

31P-saturation-transfer nuclear-magnetic-resonance measurements of phosphocreatine turnover in guinea-pig brain slices.

The technique of 31P saturation-transfer n.m.r. was used to determine the forward and the reverse rate constants of creatine phosphotransferase in superfused guinea-pig cerebral tissues in vitro. The calculated forward rate constant of 0.22 +/- 0.03s-1 compared well with a previously reported value for rat brain in vivo [Shoubridge, Briggs & Radda (1982) FEBS Lett. 140, 288-292]. The reverse rate constant was found to be 0.55 +/- 0.10s-1. 3. By using concentrations of ATP and phosphocreatine estimated previously for this superfused preparation [Cox, Morris, Feeney & Bachelard (1983) Biochem. J. 212, 365-370], forward and reverse flux rates were calculated to be 0.68 and 0.72 mumol X s-1 X g-1 respectively. The concordance of forward and reverse fluxes contrasts with the situation observed in vitro in other tissues, and suggests that the creatine phosphotransferase reaction is at equilibrium under the conditions used here. 4. Lowering the concentration of glucose in the superfusing medium from 10mM to 0.5mM had no significant effect on phosphocreatine concentration or on the forward (ATP-generating) flux through creatine phosphotransferase. The results indicate that a normal phosphocreatine content in the presence of lowered glucose availability is reflected by an unchanged turnover rate.

Animals↗

PubMed1990

[The synergistic action of glutamic acid and phosphocreatine on the metabolism and function of the heart during ischemia and reperfusion].

The combined effect of glutamic acid (15 mM) and phosphocreatine (10 mM) on metabolism and postischemic recovery of cardiac function was studied in isolated perfused working guinea pig hearts. Addition of these two agents into standard hyperpotassium cardioplegic solution increased twice the recovery of the aortic output and improved restoration of volume work and an index of functional recovery. This effect was combined with the complete recovery of ATP, phosphocreatine, the decrease in ammonia and lactate tissue contents and preservation of amino acid pool. Lesser leakage of creatine and creatine kinase pointed to lesser damage of the sarcolemma. The results show the effectiveness of the use of cardioplegic solution containing both glutamic acid and phosphocreatine.

Animals↗

PubMed1988

[Study of the nonspecific effect of phosphocreatine disodium salt on the process of excitation conduction in acute myocardial ischemia].

The effect of phosphocreatine and phosphocreatinine disodium salts on excitation conduction in acute myocardial ischemia was investigated, using repeated short-term ischemia exposures of the isolated rabbit ventricular septum as a model. Considerable improvement of excitation conduction through ischemized myocardium, seen after the administration of phosphocreatine and phosphocreatinine salts, was shown to be associated with Na+ added to the perfusion medium. Phosphocreatine and phosphocreatinine effects on excitation conduction time and the septal force in control perfusion were related to both the addition of Na+ and the binding of Ca2+ by these agents in the perfusion medium.

Acute Disease↗

PubMed1988

[High specificity in the molecular mechanism of the protective action of phosphocreatine on the myocardium in ischemia].

To study the character of the mechanism of protective action of phosphocreatine on ischemic myocardium the effects of phosphocreatine (PCr) and phosphoarginine (PArg) were compared. PCr and PArg were shown to expose identical Ca2+-chelating properties and were used as their Na-salts. Only PCr protected the cardia function during ischemia and simultaneously inhibited the accumulation of lysophosphoglycerides, products of phospholipid degradation. PArg failed to exert both of these effects. By an EPR probe method PCr was shown to increase the order of structural organization of phospholipids in the cardiac sarcolemmal vesicles. The results show that the effect of PCr on ischemic myocardium is not due to nonspecific changes in the ion composition of a solution, but most probably due to highly specific effect of phosphocreatine on the phospholipid membrane of the cardiac cells sarcolemma.

Animals↗

PubMed1987

Enzyme termini of a phosphocreatine shuttle. Purification and characterization of two creatine kinase isozymes from sea urchin sperm.

Two isozymes of creatine kinase have been purified from sperm of the sea urchin, Strongylocentrotus purpuratus. One isozyme was purified from the sperm flagellum, and the other from the head. Both require nonionic detergent for extraction from sperm. The flagellar isozyme is a monomeric species with an Mr of 145,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 126,000 from sucrose density gradient and gel filtration analyses. Creatine kinase from sperm heads was localized to the mitochondrion by an antibody raised against mouse muscle creatine kinase. This purified mitochondrial isozyme is multimeric, with an Mr of 47,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but 240,000 for the native enzyme. Peptide mapping indicates that the two isozymes are not related. The following kinetic characteristics were observed for the purified flagellar and mitochondrial isozymes, respectively. In the direction of ATP formation, at pH 6.6 and 25 degrees C, specific activities were 235 and 180 units/mg; pH optima were 6.7 and 6.9 and Michaelis constants were 0.13 and 0.055 mM for ADP and 5.8 and 2.7 mM for phosphocreatine. In the direction of phosphocreatine formation, at pH 7.5 and 25 degrees C, specific activities were 29 and 47 units/mg; pH optima were 7.5 and 7.7 and Michaelis constants were 0.89 and 0.31 mM for ATP and 39 and 62 mM for creatine. These unique isozymes constitute the termini of the phosphocreatine shuttle of sea urchin sperm that is responsible for energy transport from the mitochondrion to the distal flagellum (Tombes, R. M., and Shapiro, B. M. (1985) Cell 41, 325-334; Tombes, R. M., Brokaw, C. J., and Shapiro, B. M. (1987) Biophys. J., 52, 75-86).

Amino Acids↗

PubMed1985

[Study of the protective effect of phosphocreatine on the ischemic myocardium during cardioplegia using the P-31 NMR method].

Using 31P-NMR technique it was shown that exogenous phosphocreatine (10 mM) added in the cardioplegic solution provided higher levels of recovery of intracellular ATP (approx. 60% vs. 26% in the control) and phosphocreatine (90% vs. 43%) in perfused rat hearts after 35 min of total ischemia. Simultaneously significantly higher levels of contractile recovery (90% vs. 35%) and a three-fold decrease in creatine kinase release into the perfusate were observed. These effects of exogenous phosphocreatine can be related to either intracellular action of this compound or its interaction with cellular membrane.

Adenosine Triphosphate↗

PubMed1985

[Pharmacokinetics of phosphocreatine in the blood serum of man, dogs and rabbits].

It is shown that a single intravenous injection of phosphocreatine to man or to experimental animals is followed by its rapid clearance from blood serum. This clearance is biphasic in nature with a half-life of 3-5 min at the first rapid stage and of 20-33 min at the next slower stage. To maintain the constant phosphocreatine concentration in blood, it is necessary to infuse it at a rate comparable to that of clearance. In particular, in blood serum of man, the phosphocreatine concentration can be kept at the level of 0.2 mM if it is injected at a rate of 60 mg/h per kg bw.

Animals↗

PubMed1985

[Effect of phosphocreatine and phosphocreatinine on membrane phospholipid metabolism in acute myocardial ischemia].

The effect of phosphocreatine and phosphocreatinine on changes in crude lysophosphoglycerides (LPG) in the plasmatic membranes of canine heart, induced by short-term ischemia (an 8-minute-long occlusion of the left descending coronary artery), was examined. Ischemia caused a considerable rise in LPG level, with a mean 83% rise in lysophosphatidyl choline and a 168% rise in lysophosphatidyl ethanolamine. Intravenous administration of 300 mg/kg phosphocreatine or phosphocreatinine completely prevented the accumulation of LPG in the ischemic area. Since LPG have pronounced arrhythmogenic properties, the data obtained suggest that anti-arrhythmic activity of phosphocreatine and phosphocreatinine in acute myocardial ischemia results from the effect these substances have on membrane phospholipid metabolism in the ischemized area.

Animals↗

PubMed1966

Serum aldolase and phosphocreatine kinase in umbilical cord blood.

Aldolase was estimated in the cord blood of 81 newborn infants and phosphocreatine kinase in 87 infants. There is a wide range in the results, with some values falling in the range reported in children with muscular dystrophy or of carriers of the disease. There is no correlation of the serum enzyme levels with the infant's birth weight. High levels of phosphocreatine kinase were found in infants of mothers with pre-eclamptic toxaemia. A single estimation of cord phosphocreatine kinase and aldolase is of little help in determining whether or not an infant has muscular dystrophy.

Journal Article↗

PubMed1996

Inhibitory effects of O-benzyl-phosphocreatine ethyl ester in rabbit myocardium.

O-benzyl-phosphocreatine ethyl ester (BPC-EE) applied in superfusion evoked a negative chronotropic effect in the sinus node strips. The drug reduced the action potential amplitude and duration, decreased the resting potential, and diminished the isometric tension in the atrial trabeculae and papillary muscles. BPC-EE acted in a dose-dependent manner, and at 2.5 mmol/l it abolished the electrical phenomena in the examined preparations. BPC-EE lowered also the ATP and phosphocreatine content and decreased the creation kinase activity in ventricular specimens. The last finding is probably responsible for the remaining effects of BPC-EE.

Animals↗

PubMed1994

Electrophysiologic and inotropic effects of O-benzyl-phosphocreatine in rabbit myocardium.

O-benzyl-phosphocreatine-Na (BPC) applied in superfusion increased the action potential amplitude and isometric tension in the isolated sinus node strips, atrial trabeculae and papillary muscles. BPC enhanced the slope of the slow diastolic depolarization evoking the positive chronotropic effect. The drug prolonged the action potential duration in the atrial and ventricular cells. BPC exerted similar effects during hypoxia and cyanide superfusion in the working myocardium. On the other hand, phosphocreatine as well as O-benzyl-phosphoglycocyamine added to the superfusion fluid were ineffective. BPC increased also the ATP content of the superfused contracting atrial trabeculae. These results suggest that BPC crosses the sarcolemma, elevates the ATP content, and thereby it increases the slow inward and can serve as an additional source of the metabolic energy in the cardiac cells.

Action Potentials↗

PubMed1992

Astrocyte volume regulation and ATP and phosphocreatine concentrations after exposure to salicylate, ammonium, and fatty acids.

Cellular volume regulation following swelling in hypo-osmotic phosphate-buffered saline (PBS) and ATP and phosphocreatine concentrations of cells incubated in iso-osmotic or hypo-osmotic PBS were measured in primary cultured rat cerebral astrocytes exposed for 30 min to NH4Cl, salicylate, hexanoate, octanoate, and/or dodecanoate. These compounds have been implicated in the pathogenesis of cerebral edema in Reye's Syndrome. NH4Cl (0.10 - 10 mM) had no effect on astrocyte volume regulation or ATP concentration. Salicylate significantly reduced ATP concentrations at 3.0 mM and 10 mM but had no effect on volume regulation. Hexanoate (10 mM and 30 mM) decreased astrocyte ATP content by over 80% while octanoate (10 mM) reduced ATP content by more than 50%. Concentrations of these fatty acids at or below 3.0 mM had no effect on ATP content. Volume regulation was inhibited by 3.0 mM hexanoate and 3.0 mM octanoate but not lower concentrations. Dodecanoate (0.1-3.0 mM) decreased cellular ATP content by 33-51% in iso-osmotic PBS solutions. Phosphocreatine content was reduced by exposure to salicylate or octanoate at concentrations which had no effect on ATP content. These results indicate that astrocyte energy metabolism and volume regulation may be compromised by agents associated with cerebral edema in Reye's Syndrome. Analysis of the dose-dependence of these effects suggests that inhibition of astrocyte energy metabolism is not sufficient to affect volume regulation.

Adenosine Triphosphate↗

PubMed1996

The effects of phosphocreatine introduced simultaneously into many cardiac cells.

The aim of the present study was to ascertain whether or not phosphocreatine (PC) could produce electrophysiological and inotropic effects in isolated rabbit cardiac preparations. Exogenous PC (50 mmol/l) was introduced into many cells simultaneously by the "cut-end" and "saponinated-end" methods. PC that entered the cells (opened by cutting or chemical disruption of the sarcolemma) in the loading region, passed through the preparation intercellularly and evoked the following effects in the test region. PC enhanced the spontaneous rate and probably shifted the pacemaker in sinus node strips. On the other hand, PC elevated the action potential amplitude and duration and increased the isometric tension in atrial and ventricular strips. Furthermore, PC applied into ventricular cells partially prevented the effects of hypoxia. These findings suggest that PC may act in cardiac muscle as an intercellular energy carrier. The effects of PC introduced intracellularly resembled these evoked by O-benzyl-phosphocreatine--a permanent synthetic phosphagen--applied via superfusion.

Animals↗

PubMed1986

Automated microanalysis of adenosine phosphates, phosphocreatine, creatine, and lactate in muscle.

An automated enzymatic procedure suitable for determination of ATP, ADP, AMP, phosphocreatine, creatine, and lactate in needle biopsies of human skeletal muscle (ca. 30 mg dry wt) using a fast centrifugal analyzer (Multistat III, Instrumentation Laboratory Inc.) is presented. Coefficients of variation ranged from 0.7 to 4.2% for multiple determinations of ATP, ADP, phosphocreatine, and creatine; from 6 to 24% for lactate; and from 9 to 20% for AMP. The procedure should be usable, with appropriate modification, with other tissues and with other fast centrifugal analyzers. Muscle samples are collected into liquid freon, lyophilized, and extracted with 600 microliter of 0.65 M perchloric acid. Neutralized supernatants can be stored for up to 3 years at -80 degrees C with no significant deterioration. The procedure takes much less time than similar manual procedures and gives better reproducibility, particularly for ADP and AMP.

Adenine Nucleotides↗

PubMed1989

Heart mitochondrial creatine kinase revisited: the outer mitochondrial membrane is not important for coupling of phosphocreatine production to oxidative phosphorylation.

The state of mitochondrial creatine kinase (CKmi-mi) in intact dog heart mitochondria and mitoplasts and the mechanism of its functional coupling with the oxidative phosphorylation system have been reinvestigated under different osmotic conditions and ionic compositions of the medium. It has been established that in a medium which mimics the cardiac cell cytoplasma, dissociation of CKmi-mi from the membrane of mitoplasts increases when the mitoplasts are swollen due to hypoosmotic treatment. It was shown by EPR that hypoosmotic treatment results in the enhancement of the mobility of phospholipids in the membrane bilayer. It has been also shown that when CKmi-mi is detached from the inner membrane in intact mitochondria in isotonic KCl solution, the effects of the coupling between CKmi-mi and oxidative phosphorylation via ATP/ADP translocase disappear in spite of the presence of CKmi-mi in the intermembrane space and intactness of the outer mitochondrial membrane. Therefore, this coupling cannot be explained by the "compartmented coupling" mechanism or "dynamic adenine nucleotide compartmentation" in the intermembrane space due to diffusion limitation for adenine nucleotides through the outer mitochondrial membrane, as has been supposed by several authors (F.N. Gellerich et al. (1987) Biochim. Biophys. Acta 890, 117-126; S.P.J. Brooks and C.H. Suelter (1987) Arch. Biochem. Biophys. 253, 122-132). The data obtained show that the displacement of the enzyme from the membrane results in significantly increased sensitivity of the coupled processes of aerobic phosphocreatine synthesis to inhibition by the product, phosphocreatine. Thus, all results show that under physiological osmotic and ionic conditions CKmi-mi remains firmly attached to the inner mitochondrial membrane and effectively coupled with ATP/ADP translocase due to intimate dynamic interaction between those proteins.

Animals↗

PubMed1986

Creatine kinase-catalyzed ATP-phosphocreatine exchange: comparison of 31P-NMR saturation transfer technique and radioisotope tracer methods.

Unidirectional fluxes from ATP to phosphocreatine, catalyzed by the MM isoenzyme of creatine kinase, were measured by both the 31P-NMR saturation transfer technique and radioisotope tracer ([gamma-32P]ATP) method. It was found that at 30-37 degrees C and pH 7.4, over a wide range of [phosphocreatine]/[creatine] (from 0.2 to 5.0) ratios, both methods gave the same results, showing that magnetization transfer allows determination of real fluxes under 'physiological' conditions. However, at [PCr]/[Cr] ratios higher than 5 ([ADP]free less than 30 microM) or at lower temperatures (t less than 15 degrees C, [PCr]/[Cr] approximately 1), the fluxes assessed by saturation transfer were somewhat faster than those detected by the radioisotope tracer method. These data imply that under physiological conditions phosphoryl group transfer is actually the rate-determining step of the creatine kinase reaction. In contrast, at high [PCr]/[Cr] ratios or at lower temperatures, control may be shifted from phosphoryl group transfer or distributed among other steps of the reaction.

Adenosine Triphosphate↗

PubMed1992

Effect of food restriction on the phosphocreatine energy shuttle components in rat heart.

Malnutrition has been associated with changes in cardiac metabolism and performance. We have previously reported a diabetic-type cardiomyopathy associated with chronic food restriction and weight loss. Because the creatine-phosphocreatine-creatine kinase system is important in the contractile process, we studied the components of this system in rats fed a food-restricted diet (33% of control animal intake). After 4 weeks of food restriction, total creatine kinase (CK) activities were reduced by 28% in ventricles and by 38% in atria. The CK isoenzymes in the heart were not equally affected. The BB isoenzyme was decreased by 77% and 78%, the MB isoenzyme by 45% and 43%, the MM isoenzyme by 22% and 19% and CKmito by 16% and 15% in ventricles and atria, respectively. In contrast, brain CK activity which is predominantly the BB isoenzyme, was slightly higher in the food-restricted than in control rats. Further studies on ventricular tissue from food-restricted rats revealed a 27% decline in myofibrillar CR activity and a 58% decline in myofibrillar ATPase activity. Phosphocreatine and creatine concentrations were not changed by food restriction, however, ATP was decreased by 23% in ventricles from rats on the restricted diet. Cardiac mitochondrial oxidative phosphorylation was also impaired. State 3 respiration with alpha-ketoglutarate was reduced 20% in the food-restricted heart. These changes are compared to those which we previously observed in the diabetic rat heart and the significance of these findings is discussed.

Adenosine Triphosphatases↗