Acute haemodynamic effect of taurine on hearts in vivo with normal and depressed myocardial function

The acute haemodynamic effects of taurine were studied in normal and in beta blocker (propranolol) or calcium antagonist (diltiazem) treated rabbits and in rabbits with experimentally produced chronic aortic regurgitation. The administration of taurine (25 mg.kg-1) did not affect heart rate and left ventricular end diastolic pressure but produced significant increases in left ventricular dP/dtmax, cardiac output, and left ventricular systolic pressure in control hearts, indicating that intravascularly administered taurine substantially increased cardiac performance. In propranolol (1 mg.kg-1) treated rabbits taurine significantly improved left ventricular dP/dtmax and cardiac output, which were previously depressed by propranolol. Taurine had the same effect on diltiazem (1 mg.kg-1) treated rabbits. In rabbits with aortic regurgitation a bolus injection of taurine improved cardiac performance. Continuous infusion of taurine (100 mg.h-1) also produced a significant increase in left ventricular dP/dtmax. These results suggest that taurine has a unique action as an inotropic agent and that it may be useful in the treatment of patients with congestive heart failure.

Mechanism of direct cardiostimulating actions of hydralazine

The vasodilator, hydralazine, was reported to also exert a direct positive inotropic effect on the myocardium at high concentrations. In the present study we investigated the mechanism of this positive inotropic action by using the ventricular myocardium of isolated perfused chick hearts. Hydralazine (10(-3) M) enhanced contractile force and heart rate, and elevated the myocardial cyclic AMP level. To study the Ca2+-dependent slow action potentials, the fast N+ channels were voltage-inactivated with elevated K+ (25 mM), resulting in a loss of electrical excitability. Hydralazine (10(-4) M) rapidly (less than 3 min) allowed the generation of slow action potentials and accompanying contractions by electrical stimulation. These effects of hydralazine were only partially prevented by propranolol. The results suggest that the increase of myocardial contractility produced by hydralazine is the result, at least in part, of a direct effect on the myocardium to increase Ca2+ inflow. The increased Ca2+ influx and inward slow current is due partly to activation of beta-adrenoceptors, with resultant elevation of cyclic AMP, and partly to another mechanism.

Beneficial effect of taurine in rabbits with chronic congestive heart failure

To examine the effect of daily treatment with taurine on improving the status of congestive heart failure (CHF), we used rabbits with artificially induced aortic regurgitation. Ten rabbits were treated daily with taurine (100 mg/kg by mouth) and eight with guanidinoethyl sulfonate (GES) (100 mg/kg by mouth) immediately after induction of aortic regurgitation. The cumulative mortality rate at 8 weeks in the taurine-treated CHF group was 10% (1 of 10) compared with 53% (16 of 30) in the nontreated CHF group and 75% (6 of 8) in the GES-treated CHF group (p less than 0.05). Although cardiac function (max dP/dt) in CHF rabbits was significantly decreased (p less than 0.001), taurine-treated CHF rabbits maintained the same values as control rabbits. Taurine content of the left ventricular tissue of the CHF rabbits was significantly increased (p less than 0.01). Administration of taurine and GES to control rabbits for 8 weeks affected neither the hemodynamics nor the taurine content of the heart. It was concluded that taurine slowed the rapid progression of heart failure and consequently prolonged life expectancy.

Taurine protection against experimental arterial calcinosis in mice

Combined administration of vitamin D3 and nicotine produced severe myocardial and aortic calcinosis in mice within 4 days. Treatment of these mice with taurine increased the survival rate of the mice and reduced the elevation of calcium content in both aorta and myocardium as did diltiazem treatment. The present study suggests that taurine which is capable of regulating calcium flux may also prevent the progression of arteriosclerosis.

Protective effect of taurine against isoprenaline-induced myocardial damage

The effect of the sulfur amino acid, taurine, was examined on histological and biochemical changes induced by a toxic dose of isoprenaline in chick hearts. Isoprenaline treatment (80 or 240 mg/kg id twice daily for 4 days) caused a dose-dependent increase in heart weight and decrease in myocardial ATP. Isoprenaline administration (240 mg/kg id twice daily) produced necrotic changes in hearts, such as eosinophilic degeneration, myolysis, interstitial oedema, fibrosis, and inflammatory cell infiltration. Substantial accumulation of calcium was also observed. Taurine content of the heart was not significantly decreased. Parenteral administration of taurine (200 mg/day for 7 days) partially protected against these necrotic changes induced by isoprenaline. It is suggested that the protective effect of taurine against isoprenaline-induced myocardial injury might be due in part to the prevention of the massive overloading with calcium which is thought to cause myocardial cell necrosis.

Effects of taurine on the electrical and mechanical activities of embryonic chick heart

The effect of taurine (2-aminoethanesulphonic acid) on myocardial slow action potentials (APs) and accompanying contractions was examined in isolated perfused chick hearts and reaggregated cultured cells. Isoproterenol (ISO), histamine (HIS), or tetraethylammonium (TEA) induced slow APs and contractions in hearts whose fast Na+ channels had been inactivated by elevated K+. Taurine (10 mM) not only failed to induce slow APs, but actually decreased ISO (10(-8) M), HIS (10(-4) M), or TEA (10 mM) induced slow APs and contractions transiently (about 30s-2 min after the addition of taurine). The properties of the slow APs recovered to control levels by 7-13 min after the addition of the taurine; at this time, there was an increase in developed tension of the contraction accompanying the slow APs. These results suggest that the positive inotropic action of taurine is not mediated through an increase in the slow inward Ca2+ current. However, the transient depression of Ca2+-dependent slow APs by taurine probably explains the transient negative inotropic effect of taurine.

Protective effect of taurine against decline of cardiac slow action potentials during hypoxia

The effect of taurine on cardiac slow action potentials (APs) during hypoxic superfusion was studied in isolated guinea-pig papillary muscles. Ca2+-dependent slow APs were induced by isoproterenol (10(-6) M) in preparations which were voltage-inactivated by high (25 mM) K+. Although taurine had no effect on the slow AP parameters during normoxia, taurine (10 mM) superfusion significantly protected against the decline of slow APs produced by hypoxia. Taurine also restored slow APs that had been previously abolished by hypoxia. Therefore, taurine exposure may protect the Ca2+ slow channels which are inhibited or blocked by hypoxic conditions.

Stimulation of cardiac slow Ca++ current by high concentration of cimetidine

Electrophysiological studies on the cardiac effects of a H2-antagonist, cimetidine, were examined in three kinds of preparations: guinea-pig papillary muscles, rat left atria and perfused chick hearts. Cimetidine (10(-5) to 10(-4) M) depressed or abolished the slow action potentials (APs) induced by histamine (10(-5) to 10(-4) M) in hearts whose fast Na+ channels had been inactivated by 25 mM K+. Higher concentrations of cimetidine (10(-3) to 5 X 10(-3) M) increased myocardial cyclic AMP level and allowed the generation of slow APs in such inexcitable tissues. These cimetidine-induced slow APs were not prevented by propranolol (10(-6) to 10(-5) M) or pretreatment with 6-hydroxydopamine (50 mg/kg). These results suggest that cimetidine, in doses higher than that required to block cardiac H2-receptors, may have a cardio-stimulating action mediated through increase of inward Ca++ current.

Taurine's possible protective role in age-dependent response to calcium paradox

When hearts were reperfused with Ca++ after a short period of Ca++-free perfusion, irreversible loss of electrical and mechanical activity was observed. This phenomenon, first described by Zimmerman and Hulsmann, was termed the "calcium paradox". Chizzonite and Zak recently reported that rat hearts exhibited an age-dependent response in a calcium paradox model. The taurine (2-aminoethanesulfonic acid) content of hearts in the newborn animal is high, and decreases rapidly during the first few days of life. The present experiments were performed to test whether the myocardial taurine content was closely linked to an age-dependent response in the calcium paradox model, using post-hatched chicks. The mechanical dysfunction of the heart was much more severe in 9-day-old post-hatched chicks than in 2-day-old chicks when the hearts were subjected to the calcium paradox. Myocardial taurine content was lower in the 9-day-old chicks than in the 2-day-old chicks. The age-related response to the calcium paradox was partially protected by oral pretreatment with taurine, and there was a small increase in myocardial taurine level. It is proposed that myocardial taurine is one factor in the protection against the calcium paradox phenomenon.

Therapeutic effect of taurine in congestive heart failure: a double-blind crossover trial

In a double-blind, randomized, crossover, placebo-controlled study, we investigated the effects of adding taurine to the conventional treatment in 14 patients with congestive heart failure for a 4-week period. Compared with placebo, taurine significantly improved the New York Heart Association functional class (p less than 0.02), pulmonary crackles (p less than 0.02), and chest film abnormalities (p less than 0.01). A benefit of taurine over placebo was demonstrated when an overall treatment response for each patient was evaluated on the basis of clinical examination (p less than 0.05). No patient worsened during taurine administration, but four patients did during placebo. Pre-ejection period (corrected for heart rate) decreased from 148 +/- 14 ms before taurine treatment to 137 +/- 12 ms after taurine (p less than 0.001), and the quotient pre-ejection period/left ventricular ejection time decreased from 47 +/- 9 to 42 +/- 8% (p less than 0.001). Side effects did not occur in the patients during taurine. The results indicate that addition of taurine to conventional therapy is safe and effective for the treatment of patients with congestive heart failure.

Beneficial effect of coenzyme Q on myocardial slow action potentials in hearts subjected to decreased perfusion pressure-hypoxia-substrate-free perfusion

Coenzyme Q, an important component of the electron transfer system in mitochondria, plays a central role in energy production aerobically. The effect of pretreatment with coenzyme Q10 (Co Q) on myocardial slow action potentials (APs) and accompanying contractions and on myocardial high energy phosphate content was studied in perfused hearts subjected to decreased perfusion pressure-hypoxia-substrate-free. Post-hatched chicks were treated i.p. with 10 mg/kg of Co Q daily for 5 days. To study the slow APs exclusively, the fast Na+ channels were voltage-inactivated by elevated K+ (25 mM) Tyrode solution. The Ca++-dependent slow APs were induced by elevating [Ca]o to 5.4 mM; hearts were paced at a rate of 40 per min. Hearts which had been pretreated with Co Q were protected against the deleterious effect of decreased perfusion pressure - hypoxia - substrate-free perfusion on mechanical performance accompanying the slow Ca++-Na+ APs. The slow APs in hearts pretreated with Co Q were also less affected than were non-treated hearts. However, the myocardial ATP and total adenine nucleotides were not affected by exogenous Co Q. It was suggested that exogenous Co Q could protect against the decline of cardiac contractions via improved availability of slow APs during decreased perfusion pressure - hypoxia - substrate-free, independently of the cellular high energy phosphate level.

Thrombosis of a prosthetic valve managed by thrombolysis: a case report

Thrombosis of a prosthetic valve is one of the most serious cardiovascular events. Emergency replacement of the prosthetic valve has been the standard method of management but carries a high operative risk. This paper describes the successful use of streptokinase, given intravenously, to manage a patient with this complication in the acute phase. Eventually, operation was necessary because the presence of residual organized clot was suspected, but the procedure was performed electively 10 days later.

Beneficial effect of taurine on congestive heart failure induced by chronic aortic regurgitation in rabbits

Taurine (2-aminoethanesulfonic acid) is known to have a cardiotonic action. The present study was designed to see whether oral treatment with taurine could improve the status of congestive heart failure induced by aortic regurgitation. Nine rabbits were treated daily with taurine (100 mg/kg) after producing aortic regurgitation. Cumulative mortality at 8 weeks in the non-treated group was 52% compared with 11% in the taurine-treated group (p less than 0.05). Cardiac function (max dP/dt) was significantly decreased in rabbits with aortic regurgitation, whereas in taurine-treated rabbits, cardiac function was maintained the same as control. The present data suggest that taurine prevented the rapid progress of heart failure, and consequently prolonged the life expectancy.

Enhanced suppression of myocardial slow action potentials during hypoxia by free fatty acids

Effects of free fatty acids (palmitate and linoleate) on myocardial contractility and slow action potentials (APs) were examined in Langendorff-perfused chick hearts. To study the slow APs exclusively, the fast Na+ channels were voltage-inactivated in elevated K+ (25 mM), and the concentration of Ca2+ ion was increased to 5.4 mM in order to induce slow APs. Palmitate (0.18, 0.54 or 0.72 mM) along with albumin (0.12 mM) was added to the perfusate. Albumin by itself did not affect contractility or the slow APs during normoxia and hypoxia. Under well oxygenated conditions, palmitate had no effect on contractility or the slow APs. However, palmitate accelerated the decline of contractility during hypoxia in a dose-dependent fashion. Hypoxia suppressed the slow APs, and palmitate and linoleate further exacerbated the suppression of slow APs produced by hypoxia. Nevertheless, palmitate and linoleate did not enhance the hypoxic reduction of the tissue high energy phosphate level. The present results suggest that free fatty acids elicit cardio-depressant effects on hearts through their direct action on the myocardial cell membrane (slow channels) rather than through any metabolic effects.

Protection by oral pretreatment with taurine against the negative inotropic effects of low-calcium medium on isolated perfused chick heart

Chicks were given taurine by mouth using a cannula pushed down into the oesophagus. This treatment had protected the heart, when subsequently removed, against the decline of contractile force in the perfused heart brought about by low-calcium media. A small but statistically significant increase in taurine concentration occurred in the ventricular tissue of such pretreated hearts. In contrast, pretreatment with taurine did not affect ventricular calcium level. Addition of taurine (3 to 100 mmol . litre-1) into the perfusing solution did not alter the cyclic AMP level in the control perfused hearts, and failed to induce slow channel action potentials in hearts whose fast Na+ channels had been inactivated by high K+ (25 mmol . litre-1). However, taurine perfusion produced a significant positive inotropic action which became stable after 5 to 10 min of exposure.

Concentration-dependent effect of trapidil on slow action potentials in cardiac muscle

Trapidil, a coronary vasodilator and positive inotropic agent, was tested for its ability to affect the normal "fast" action potentials and the "slow" action potentials and contractions of isolated perfused chick hearts, and to affect the tissue cyclic AMP level. At 5 X 10(-3) M, trapidil completely blocked the fast Na+ channels in hearts perfused with normal Tyrode solution, since this dose abolished the action potential when verapamil (2 X 10(-6) M) was present to eliminate the inward slow current. To study effects on the slow channels, the fast Na+ channels were voltage-inactivated by partial depolarization to about -40 mV with an elevated (25 mM) K+-Tyrode solution, resulting in loss of excitability. At low concentrations (1 X 10(-4) - 1 X 10(-3) M), trapidil induced slow action potentials accompanied by contractions, even in the presence of a beta-adrenergic blocker. In contrast, at high concentrations (3 X 10(-3) - 1 X 10(-2) M), trapidil markedly depressed or blocked the isoproterenol-induced slow action potentials. Consistent with this dual action, in hearts perfused with normal Tyrode solution, trapidil exerted a small positive inotropic action at low doses and a considerable negative inotropic action at high doses, even though the intracellular cyclic AMP level was substantially elevated. That is, trapidil has actions similar to those of papaverine. It is concluded that trapidil blocks both fast Na+ channels and slow channels in cardiac muscle, the fast Na+ channels being more sensitive, and that low concentrations of trapidil induce slow channels by elevating the cyclic AMP level because of phosphodiesterase inhibition.

Trapidil stimulation of slow Ca2+ current in cardiac muscle

The effect of trapidil, a coronary vasodilator and positive inotropic agent (associated with elevated tissue cyclic AMP levels due to phosphodiesterase inhibition), was examined on the electrophysiological properties of cardiac muscle. Specifically, the trapidil was tested for its ability to induce slow action potentials (APs), and to affect the maximum upstroke velocity (+Vmax) of the slow APs in the ventricular myocardial cells of isolated perfused chick hearts. The effect of trapidil on the contractions accompanying the slow APs and on the tissue cyclic AMP levels was also examined. To study the slow channels exclusively, the fast Na+ channels were voltage-inactivated by elevated (25 mM) K+. In this condition of functional removal of the fast channels, the hearts could not be excited even by intense electrical stimulation. It was found that trapidil (10(-4)--10(-3) M) induced slow APs accompanied by contractions. Elevation of the trapidil concentration produced dose-dependent increases in +Vmax, dT/dt (first derivative of developed tension) and cyclic AMP. These effects of trapidil were not affected by propranolol, suggesting that they were not mediated by beta-adrenergic receptors. These results support the hypothesis that intracellular cyclic AMP levels regulate the number of available slow channels, thereby controlling contractile force in the heart muscle via the Ca2+ influx mediated by slow channels.

Process of attachment of phi X174 parental DNA to the host cell membrane

The phi X174-DNA membrane complex was isolated from Escherichia coli infected with phi X174 am3 by isopycnic sucrose gradient centrifugation followed by zone electrophoresis. The phi X174 DNA-membrane complex banded at two positions, intermediate density membrane fraction and cytoplasmic membrane fraction, having bouyant densities of 1.195 and 1.150 g/ml, respectively. Immediately after infection with phi X147, replicating DNA was pulse-labeled and then the incorporated label was chased. The radioactivity initially recovered in the intermediate density membrane fraction migrated to the cytoplasmic membrane fraction. The DNAs from both complexes sedimented mainly at the position of parental replicative form I (RFI). The phi X174 DNA-membrane complex contained a speficic membrane-bound protein having a molecular weigth of 80,000 which is accumulated in the host DNA-membrane complex. These results suggest that when phi X174 DNA penetrated into cells in the early phase of infection, single-stranded circular DNA was converted to parental RFI at a wall/membrane adhesion region and migrated to the cytoplasmic membrane fraction, where the parental RF could serve as a template in the replication of progeny RF.

Clinicopathological correlations in patients who received an isolated model 104 Beall mitral valve

Following reports of accelerated wear in the model 104 Beall prosthetic valve, the authors initiated a recall and prospective follow-up study of patients who received Beall valves. In the 3 years of the follow-up program, 12 patients who had an isolated Beall mitral valve implanted have had elective replacement of the prosthesis. Cinefluoroscopy was the most accurate preoperative method of predicting the degree of pathologic wear. The serum lactic dehydrogenase value was the next most helpful measurement. Change in functional class, mitral regurgitation murmur, hemodynamic status, echocardiography and the duration of the valve in situ were not sensitive indicators.

Yohimbine blockade of ionic channels in myocardial cells

The effects of yohimbine, an alkaloid shown to have local anesthetic properties on nerve, were determined in isolated perfused chick embryonic (19--21-day-old) hearts. Effects on the fast Na+ channels were studied in hearts perfused with normal Ringer solution by using the maximal upstroke velocity (+Vmax) as an index of the inward current flowing during the rising phase of the normal action potential. Yohimbine (10(-5)--10(-4) M) depressed +Vmax and overshoot and prolonged the action potential. At 5 x 10(-4) M, yohimbine completely blocked the fast Na+ channels, since this dose abolished the action potential when Mn2+ (2 mM) was present to eliminate the slow Ca2+ current. Effects on the slow channels were studied in hearts in which the fast Na+ channels were voltage-inactivated by partial depolarization to about--40 mV with an elevated (25 mM) K+-Ringer solution or blocked by tetrodotoxin (TTX), resulting in loss of excitability. Isoproterenol (10(-6) M) restored excitability by inducing a slowly rising overshooting electrical response (the "slow response") that was accompanied by contractions. At low concentrations (10(-5)--10(-4) M), yohimbine enhanced the isoproterenol-induced slow response; yohimbine induced the slow response in the absence of isoproterenol, even in the presence of a beta-adrenergic blocker. In contrast, at high concentrations (10(-3) M), yohimbine markedly depressed or blocked the slow response. Consistent with this dual action, yohimbine exerted a small positive inotropic action at low doses in hearts perfused with normal Ringer solution and exerted a considerable negative inotropic action at high doses, causing complete blockade of the contractions within 20 min. Cultured reaggregated cells obtained from chick embryo (15--17 day-old) ventricles showed a similar response to yohimbine in that both the normal action potentials and the slow responses were abolished. It is concluded that yohimbine exerts a local anesthetic-like action on myocardial cells, since both fast and slow channels were blocked, but the fast channels were more sensitive to yohimbine.

Studies on pig serum lipoproteins. V. Optical properties of low density lipoproteins

The circular dichroism (CD), optical rotatory dispersion (ORD), and fluorescence emission spectra of two subfractions of pig serum low density lipoproteins (LDL1 and LDL2) were compared. The contribution of the carbohydrate moiety to the CD and ORD spectra was estimated on the basis of data obtained from isolated glycopeptides and the constituent monosaccharides. The carbohydrate moiety had no effect on the conformation of the protein moieties of LDL1 and LDL2 (apoLDL1 and apoLDL2). However, the intensities of the observed extrema in the CD and ORD spectra of the glycopeptides were greater than those expected from the monosaccharide composition. This suggests the existence of secondary structure in the carbohydrate moiety. In contrast to the carbohydrate moiety, the contribution of the lipid moiety to the CD and ORD spectra could not be neglected. When the effect of the lipid moiety was subtrated from the CD and ORD spectra, the spectra due to apoLDL1 and apoLDL2 were quite similar. Delipidation in the presence of sodium dodecyl sulfate (SDS) induced an increase in the content of disordered structure and alpha-helix accompanied by a decrease in the beta-structure. In the presence of SDS, marked quenching occurred in the fluorescence emission spectra with a blue shift of the maximum emission wavelength from 332 to 326 nm. ApoLDL1 and apoLDL2 showed quite similar SDS-induced conformational transitions. The secondary structures of apoLDL1 and apoLDL2 in the native lipoproteins were stable to changes of pH and temperature. However, this stability was lost in the presence of SDS. These results suggest the importance of the lipid moiety in maintaining the native secondary structures of LDL1 and LDL2. From the overall similarity of the optical properties of apoLDL1 and apoLDL2, we conclude that the secondary structures of apoLDL1 and apoLDL2 are identical.

Studies on pig serum lipoproteins. IV. Isolation and characterization of glycopeptides from pig serum low density lipoprotein

Three glycopeptides were isolated from the pronase digest of the protein moiety of pig serum low density lipoprotein. The isolation procedure consisted of pronase digestion, gel filtration on Sephadex G-25 and G-50 columns, paper chromatography and DEAE-Sephadex A-50 column chromatography. Based on the carbohydrate analysis, the isolated glycopeptides were classified into two types. One type (GDI) consisted of mannose and N-acetylglucosamine residues in the molar ratio of 6:2 and had a molecular weight of about 2,300. The other type (GDII and GDIII) consisted of sialic acid, mannose, galactose, fucose, and N-acetylglucosamine residues in the molar ratio of 1:4:2:1:3 and 2:4:3:1:3, respectively. The molecular weights of GDII and GDIII were about 2,100 and 3,100, respectively. The results on the strong alkaline treatment of these glycopeptides suggested that all carbohydrate chains were linked to the peptide chains through N-acetylglucosaminyl-asparagine linkages. Of these glycopeptides and pig serum lipoproteins, only glycopeptide GDI and native LDL strongly interacted with concanavalin A.

A correlative study on the changes of cardiac dynamics and myocardial energy liberation in blood-let dogs

Blood-letting of 450 to 1,000 ml with or without saline infusion was performed in dogs. In some dogs, right atrial pacing was carried out during blood-letting. Heart rate and isometric time-tension index were measured as the indicators of chronotropism and inotropism, respectively. After 60 min of blood-letting, dogs were sacrificed and mitochondria were isolated from the left ventricular myocardium. Mitochondrial respiration was measured polarographically and respiratory control index was calculated. As blood-letting advanced, the hearts revealed negative chronotropism with negative inotropism. Mitochondrial respiration was suppressed. When heart rate was forced to increase with atrial pacing, the hearts showed positive chronotropism with negative inotropism. Respiratory control index of mitochondria was deteriorated, showing uncoupling of oxidative phosphorylation. In consideration with our previous study on the ischemic heart, it is concluded that uncoupling of oxidative phosphorylation appeared in hypoxic myocardium when cardiac dynamics shifted to positive chronotropism with negative inotropism, though suppression of mitochondrial respiration was revealed when cardiac dynamics altered to negative chronotropism with negative inotropism.

Apparent deficiency of vitamin B6 in typical individuals who commonly serve as normal controls

Individuals who typically serve as normal controls were found by the differential assay of the glutamic oxaloacetic transaminase in their erythrocytes to have a deficiency (P less than 0.001) of enzyme activity as well as a deficiency (P less than 0.001) of pyridoxal phosphate. Contrary to the understanding that the diet provides an adequate intake of vitamin B6, the dietary intake of vitamin B6 of these controls was inadequate.

An experimental study of the effect of glucose-insulin-potassium solution on energy metabolism of infarcted cardiac muscle

The effect of GIK (glucose-insulin-potassium) infusion on the energy liberation of the infarcted heart muscle was studied experimentally in relation to epicardial electrocardiographic changes and cardiac dynamics. In the case of 30-min coronary ligation, the spread of the zone showing ST segment elevation was not depressed significantly, but the mean voltage values of ST elevations were suppressed in the peri-infarcted area, and the uncoupling of oxidative phosphorylation in the peri-infarcted area was also obscured by the GIK treatment. Cardiac dynamics did not change with GIK treatment. On the other hand, in the 60-min coronary ligation, the spread of the zone showing ST segment elevation was reduced significantly and the negative inotropism induced by coronary ligation was suppressed with GIK infusion. However, the uncoupling of oxidative phosphorylation in the infarcted area and in the peri-infarcted area did not show any significant improvement. Therefore, the disturbed energy metabolism of the peri-infarcted area of 30-min ligation might be improved by the effect of GIK infusion. These data suggested that the GIK infusion improved the energy liberation of the so-called twilight zone at 30 min after ligation, and then reduced the genuine infarcted zone after 60 min of ligation.

Vitamin B6 deficiency in patients with a clinical syndrome including the carpal tunnel defect. Biochemical and clinical response to therapy with pyridoxine

Ten individuals having a severe clinical status associated with the carpal tunnel syndrome were selected for treatment with pyridoxine. The status of vitamin B6, as pyridoxal phosphate, was determined by the specific activities of the glutamic oxaloacetic transaminase of the erythrocytes (EGOT). Before treatment, the patients showed a deficiency of vitamin B6 as determined by 1) a comparison of the specific activities of EGOT with those of a control group (P less than 0.001); and 2) a differential assay based upon the principle of unsaturation and saturation of a Coenzyme-Apoenzyme System (CAS), as applied to EGOT. These patients were treated with pyridoxine, and the specific activities of EGOT were determined after 2 and 4 weeks. Not only was there a disappearance of the deficiency of pyridoxal phosphate, but the level of EGOT activity increased 55-68% during 2-4 weeks, respectively. More apoenzyme was apparently biosynthesized, because the specific activities were significantly higher than before therapy (P less than 0.001/4 wks). Clinical evaluation showed a great improvement in their status, and anticipated surgery for some of the patients became unnecessary. It is concluded that patients with a severe syndrome including the carpal tunnel defect have a deficiency of vitamin B6, and that both the syndrome and the deficiency are relived by therapy with pyridoxine.

Studies on pig serum lipoproteins. I. Separation and properties of low-density lipoproteins

The low-density lipoproteins in pig serum were separated into two subclasses (LDL1 and LDL2) by 2 to 7% pore size gradient gel electrophoresis. Preparative gel electrophoresis in 2 to 4% gradient gel made it possible to isolate these components as distinct entities. After delipidation by chromatography on Sepharose 4B in the presence of SDS, both apo-LDL1 and apo-LDL2 were found to have a molecular weight of 2.6X10(5). However, when these apoproteins were incubated in 10% sodium dodecyl sulfate, fragmentation occurred and the minimum fragment molecular weight was estimated to be 2.4X10(4). No essential difference was found in the amino acid compositions or fragmentation patterns of the apoproteins. However, the amounts of carbohydrates in the two apoproteins were different (7.09% in apo-LDL1 and 5.08% in apo-LDL2). The carbohydrate composition was 0.8% sialic acid, 2.38% N-acetyl-glucosamine, and 4.01% neutral sugars in apo-LDL1 and 0.5, 1.75, and 2.83% in apo-LDL2, respectively. In both apoproteins, mannose, galactose, and fucose were present in almost the same molar ratio of 4-5 : 2-3 : 1.