Osmotic properties of bovine erythrocytes aged in vivo

The osmotic properties of bovine erythrocytes aged in vivo were studied by the modified microhematocrit method. The osmotic fragility of older red cells decreases due to their larger relative osmotically non-active volume. Relative critical cell volume of bovine erythrocytes does not alter significantly with cell age. The age dependent change in the osmotic fragility of human red blood cells, the reverse of that found for bovine erythrocytes, is due to a different alteration of the critical cell volume during intravascular erythrocyte aging.     

Interaction between glucose utilization and left ventricular heart function in type I-diabetics

The aim of the present study was to check whether equal, therapeutically relevant, positively inotropic doses of different adrenergic agents elicit equal inotropic and metabolic effects in 6 type I-diabetics as in 6 matched nondiabetic subjects. The effects of increasing doses of norepinephrine (NE)- and orciprenaline (0.12, 0.20, 0.33 microgram/kg min) on heart function (systolic time interval, heart rate, blood pressure) and on serum fatty acid (NEFA), glucose, lactate, pyruvate and insulin concentrations were recorded. In the therapeutic dose range, NE, and orciprenaline elicited in diabetics without clinical signs of any cardiovascular disease a diminished myocardial inotropic response (20-40%), less marked vascular effects (vasoconstriction, vasodilatation), but greater metabolic changes in right atrial blood (NEFA, pyruvate, lactate) compared to matched controls (p less than 0.05). The smaller increase of cardiac performance in diabetics to exogenous catecholamines cannot be explained by sympathetic cardiac denervation, since chronotropic beta 1-beta 2-stimulation with orciprenaline provoked nearly equal dose-dependent changes in diabetics and controls. It is suggested that the smaller positive inotropic effect during NE and orciprenaline infusion in type I-diabetics is a result first of all of alterations in myocardial energy turnover in diabetes due to reduced myocardial glucose utilization. It seems necessary to secure continuous myocardial glucose utilization and subnormal NEFA concentrations in the serum during the therapeutic application of inotropic adrenergic agents in severe cardiac failure and cardiogenic shock in diabetics.     

Restriction map of permuted DNA of Erwinia carotovora temperate bacteriophage 59

The cyclic permutation and terminal redundancy were found in the genomes of Erwinia carotovora temperate bacteriophage 59 by electron microscopic studies. The headful mechanism for bacteriophage DNA cleavage and packaging during the phage morphogenesis was confirmed by the restriction analysis technique. Restriction map of the bacteriophage 59 DNA was constructed for restriction endonucleases BamHI, Bg1II, Eco31, Sa1I, SmaI, EcoRI.     

The combined effects of dopamine (DA) and the DA antagonists EGYT-2509, chlorpromazine and haloperidol on the kidney function

In anaesthetized dogs renal function was investigated in four successive 20-min periods in four experimental series. (1) In the first series following the first period (serving as control) 2.5 micrograms/kg/min of dopamine (DA) dissolved in 0.5 ml/min of Ringer's solution was infused into the left renal artery (period 2), than during periods 3 and 4. It was found that first (period 2) and second (period 3) doses of DA induced a significant decrease of about 20-30% in renal vascular resistance, and an increase of about 15-25% in renal blood flow. At the same time, systemic arterial blood pressure fell by 10%. The other investigated parameters of the left kidney (Cinulin, CPAH, sodium, potassium and water excretion) did not differ from the respective parameters of the intact right kidney. (2) In the second experimental series following the first period (prior to period 2) 1.0 mg/kg of the DA antagonist EGYT 2509 was administered intravenously. Prior to the period 3 again 1.0 mg/kg of EGYT 2509 and prior to period 4 2.0 mg/kg of EGYT 2509 was given intravenously. During periods 2 through 4 2.5 micrograms/kg/min of DA was infused into the left renal artery. It could be ascertained that EGYT 2509 abolished the renal effects of DA while not inducing any decrease in arterial blood pressure. (3) In the third experimental series, following the control period, prior to periods 2,3 and 4, 1.0 mg/kg, 1.0 mg/kg and 2.0 mg/kg chlorpromazine respectively, was administered i.v. followed by the infusion of DA into the left renal artery. After the administration of chlorpromazine arterial blood pressure and renal vascular resistance fell concomitantly and DA failed to induce any further changes in these parameters. According to our experiments chlorpromazine abolishes the effect of DA on kidney function. (4) In the fourth series, prior to DA infusion the dogs were given 0.5 mg/kg (period 2) then again 0.5 mg/kg and finally 1.0 mg/kg of haloperidol intravenously. Haloperidol decreased arterial blood pressure as well as renal vascular resistance, thus renal blood flow did not change. Renal blood flow could then be increased by DA infused into the left renal artery. It seems that haloperidol could not abolish the vascular effects of DA in the kidney. Our experiments indicate that substance EGYT 2509 possesses the most marked dopaminergic antagonistic effect, chlorpromazine had also been effective, while haloperidol had proved to be practically ineffective.     

Experimental study of the prophylactic anti-influenza and interferon-inducing activity of epsilon-aminocaproic acid

Epsilon-aminocaproic acid, an original antifibrinolytic had a rapid and prolonged protective effect, thus lowering the death rate of experimental mice contaminated with virulent strains of the influenza virus. The protective effect of the acid was observed after its intraperitoneal administration in a dose of 20 mg/mouse 24 hours before contamination by the strain with the H3N2 antigenic formula and after intranasal application of 15 mg of epsilon-aminocaproic acid divided into 2 doses 2 days before contamination by the strain with the H1N1 antigenic formula. In the animals contaminated by the H1N1 influenza virus 5 days after subcutaneous administration of the drug in a dose of 30 mg there was detected in the lungs a much lower number of the infectious viruses 3 days after the contamination. It was shown that 3 and 6 weeks after initiation of the 5-day treatment course with subcutaneous administration of epsilon-aminocaproic acid in a daily dose of 90 mg/mouse the animal resistance to the H1N1 influenza virus increased. No interferonogenic activity after administration of epsilon-aminocaproic acid was observed in the mice.     

Immunostimulating and protective effects of terrilytin preparations in staphylococcal infection

In mice infected with staphylococci there was observed less pronounced development of the immune response to sheep red blood cells (SRBC) than in intact animals subjected only to immunization. Administration of free terrilytin to the infected mice increased the immune response development induced by SRBC while the use of immobilized terrilytin normalized it. The supernatant liquid of the spleen cells (SLSC) from the mice treated with the free of immobilized terrilytins stimulated development of the immune response to SRBC in the infected animals and inhibited the function of the suppressor cells in the spleen. The immunomodulating and protective effects of the SLSC fractions isolated with column chromatography on Sephadex G-150 were investigated. Substances of the low molecular fraction of the SLSC proteins (molecular weight of 10-15 kD) from the mice treated with the terrilytins showed immunostimulating and protective properties. The factors inducing both the activity types included peptides and the ribonucleotide component playing a significant role in realization of the immunostimulating and protective effects of the free and immobilized proteases.     

Haemodynamic effects of angiotensin II in conscious, non-ascitic cirrhotic rats

The effect of angiotensin II (AII) on systemic and regional haemodynamics was studied in 18 control and 18 cirrhotic, non-ascitic conscious rats (CCl4/phenobarbital model). Cirrhotic rats were found to retain sodium and to have normal plasma renin and plasma aldosterone concentrations when compared with control animals. Cirrhotic rats showed an enhanced cardiac output (34.4 +/- 0.5 vs. 27.5 +/- 2.0 ml/min in controls) and decreased peripheral resistances (2.96 +/- 0.25 vs. 3.95 +/- 0.31 mm Hg/min/100 g/ml in controls) under basal conditions. When AII was administered cardiac output decreased by 10.7 +/- 1.2% in cirrhotic rats, whereas it increased in control animals (11.2 +/- 2%, p less than 0.005). The AII-induced increase in arterial pressure was lower in cirrhotic than in control rats. The renal blood supply was particularly impaired by AII in cirrhotics, with a maintained flow to other organs (muscle, testes). It is concluded that the response to AII is disturbed in rats with hepatic cirrhosis even in a stage without ascites and with plasma renin and aldosterone concentrations similar to those of control animals.     

Effects of bivalent cations on post-rest adaptation in guinea-pig heart muscle

In isolated papillary muscles of guinea-pig hearts, the inotropic effects of bivalent cations, Ca2+, Ba2+, Sr2+, and Ni2+, were investigated during post-rest adaptation in order to study their individual action on excitation-contraction coupling. Upon exposure to each cation studied, the force of contraction was transiently enhanced, whereas the steady state force was influenced differently: it increased with Ca2+, Ba2+ and Sr2+ and was depressed by Ni2+. The transmembrane action potentials (measured at 90% repolarization) were slightly prolonged by Sr2+ and even more by Ba2+, and were shortened by Ca2+ and Ni2+. After 10 min rest, the post-rest contractions consisted of a late peak (PII) that was enhanced in high Ca2+-solution an by Sr2+. Ni2+ and Ba2+ depressed PII and during adaptation to pre-rest controls an early peak of contraction (PI) prevailed. There was no simple relation between post-rest adaptation of force and the duration of action potential in the presence of the bivalent cations tested. During post-rest adaptation the two components of contraction can be separated. The results are interpreted in terms of a model of excitation-contraction coupling which derives Ca ions for contractile activation from two sources: transmembrane calcium influx and calcium release from cellular stores. From the different effects on post-rest adaptation it is concluded that the individual cations influence excitation-contraction coupling more specifically and not merely by "screening-off" the negative surface charges.     

Inconsistent sodium current records derived on Ranvier nodes with a commercially available potential clamp device according to Nonner

We tried to reproduce some basic implications of the Hodgkin-Huxley-Frankenhaeuser formalism by measuring sodium currents in single myelinated nerve fibres with a commercially available version of the potential clamp device according to Nonner. The following contradictory observations were made: 1. The potential dependence of the time to peak sodium currents showed a discontinuity around the sodium equilibrium potential. 2. Defining the sodium permeability PNa by the constant field equation and fitting the peak PNa-voltage relation by a sigmoid function we obtained unbelievable high values of PNa at rest. 3. Testing PNa as calculated by the constant field equation by so-called "sodium tail current" experiments we obtained instantaneous changes of PNa. Summing up, neither the kinetics of sodium currents nor the constant field concept as tested with the equipment used seem to agree satisfactorily with the standard data of sodium currents in Ranvier nodes.     

Phosphoglycerides and derivatives in Taenia crassiceps examined by 31P NMR spectroscopy

Examination of the larval stage of the tapeworm, Taenia crassiceps, by 31P NMR spectroscopy revealed the presence of a major phosphoglyceride component. However, using saturation transfer, no exchange between glycerophosphorylcholine and phosphoglyceride or any other NMR-detectable phosphorus metabolites was detected.