Effect of benzodiazepines in 5′-nucleotidase activity of rat brain

Bulletin of Experimental Biology and Medicine -     

Effect of o,p-dichlorodiphenyldichloroethane and perthane in vitro on glutathione reductase activity in the adrenals of dogs and guinea pigs

o,p-Dichlorodiphenyldichloroethane (o,p-DDD) and Perthane, when added in a concentration of 312 M to homogenate and cytoplasmic fraction of dog adrenals, activate glutathione reductase. In a concentration of 156 M, o,p-DDD and Perthane do not affect glutathione reductase activity of the dog adrenals. When given in vitro, o,p-DDD and Perthane activate glutathione reductase of the guinea pig adrenals. o,p-DDD has no effect on glutathione reductase activity of the cytoplasmic fraction of dog liver and kidney, thus confirming the high specificity of its effect on the adrenal cortex.Laboratory of Pathophysiology, Institute of Endocrinology and Metabolism, Kiev. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 2, pp. 159–161, February, 1978.     

Effect of imidazole compounds on 3′,5′-AMP phosphodiestyerase activity

The effect of 24 imidazole compounds on activity on the phosphodiesterase (3, 5-AMP phosphohydrolase; EC 3.1.4.1) from rat brain and skeletal muscles ofRana temporaria was investigated. Imidazole compounds were shown to have both an activating and an inhibitory action on the enzyme. Imidazole itself and seven of its alkyl substitution products activated phosphodiesterase. Of the inhibitors, tetrachloro-2-trifluoromethyl-benzimidazole had the strongest action on the enzyme.Group for Biophysics of Synaptic Processes, I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. (Presented by Academician S. E. Severin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 9, pp. 1055–1059, September, 1976.     

Effect of mode and schedule of administration on carcinogenic effect of N-methyl-N′-nitro-N-nitrosoguanidine in rats

Laboratory of Methods of Carcinogen Screening, Research Institute of Carcinogenesis, All-Union Oncologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Trapeznikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 109, No. 2, pp. 175–176, February, 1990.     

Renal responsiveness to parathyroid hormone in a case of nonfamilial hypophosphatemic osteomalacia

Summary Plasma immunoreactive parathyroid hormone level, urinary excretion of adenosine cyclic 3,5-monophosphate (cyclic AMP) and the sensitivity of the renal tubule to calcium infusion and to parathyroid extract were investigated in a patient with nonfamilial hypophosphatemic osteomalacia. Plasma immunoreactive parathyroid hormone concentration was normal and basal urinary excretion of cyclic AMP was increased. Renal cortical adenylate cyclase, as measured by urinary cyclic AMP excretion, was certainly as sensitive to exogenous parathyroid extract as in normal subjects. After a previous calcium infusion, a greater parathyroid-hormone-sensitive component of phosphorus transport in the kidney was present than in two control subjects. Our results indicate that in nonfamilial hypophosphatemic osteomalacia the renal tubule could be hyperresponsive to parathyroid hormone.This work was supported by a grant (n^o 20,463) from the Belgian Nationaal Fonds voor Geneeskundig Wetenschappelijk Onderzoek     

The nonselective cation channel in the basolateral membrane of rat exocrine pancreas

Nonselective Ca²⁺-sensitive cation channels in the basolateral membrane of isolated cells of the rat exocrine pancreas were investigated with the patch clamp technique. With 1.3 mmol/l Ca²⁺ on the cytosolic side, the mean openstate probabilityP _o of one channel was about 0.5. In insideout oriented cell-excised membrane patches the substances diphenylamine-2-carboxylic acid (DPC), 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) and 3,5-dichlorodiphenylamine-2-carboxylic acid (DCDPC) were applied to the cytosolic side. These compounds inhibited the nonselective cation channels by increasing the mean channel closed time (slow block). 100 mol/l of NPPB or DPC decreasedP _o from 0.5 (control conditions) to 0.2 and 0.04, respectively, whereas 100 mol/l of DCDPC blocked the channel completely. All effects were reversible. 1 mmol/l quinine also reducedP _o, but in contrast to the abov mentioned substances, it induced fast flickering. Ba²⁺ (70 mmol/l) and tetraethylammonium (TEA⁺; 20 mmol/l) had no effects. We investigated also the stilbene disulfonates 4-acetamido-4-isothiocyanatostilbene-2,2-disulfonic acid (SITS), 4,4-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS) and 4,4-dinitro-2,2-stilbenedisulfonate (DNDS). 10 mol/l SITS applied to the cytosolic side increasedP _o from 0.5 to 0.7 and with 100 mol/l SITS the channels remained nearly permanently in its open state (P _o1). A similar activation of the channels was also observed with DIDS and DNDS. These effects were poorly reversible. The stilbene disulfonates acted by increasing the channel mean open time. When the channel was inactivated by decreasing bath Ca²⁺ concentration to 0.1 mol/l, addition of 100 mol/l of SITS had no effect. Similarly, reducing bath Ca²⁺ concentration from 1.3 mmol/l in presence of 100 mol/l SITS (channels are maximally activated) to 0.1 mol/l, inactivated the channels completely. These results demonstrate, that SITS can only activate the channels in the presence of Ca²⁺. SITS had no effects, when applied to the extracellular side in outside out patches. In summary, the substances DPC, NPPB and DCDPC inhibit nonselective cation channels, where DCDPC has the most potent and NPPB the smallest effect; whereas SITS, DIDS and DNDS activate the channel when applied from the cytosolic side in the presence of Ca²⁺ ions.     

Inhibition by somatostatin of adenosine-3′,5′-monophosphate stimulated hepatic ribosomal protein synthesis

Summary Somatostatin which inhibits the secretion of various pituitary and intestinal hormones has been suspected to exert these effects by inhibiting adenosine-3,5-monophosphate accumulation in the respective endocrine gland. Our results, obtained by cell free protein synthesis and by sedimentation through sucrose gradients of ribosomes, prepared from rat liver after incubation with cyclic AMP and/or somatostatin also suggest this antagonism between somatostatin and cyclic AMP. In addition, they indicate that this antagonism is not restricted to endocrine tissues.Supported by a grant (M2-2777) of the Österreichischer Fonds zur Förderung der wissenschaftlichen Forschung     

Effect of triiodothyronine on system A amino acid transport in cells of rat submandibular gland

The effect ofL-3,5,3-triiodothyronine (T₃) on -aminoisobutyric acid (AIB) transport in isolated cell suspensions of rat submandibular gland was investigated. The uptake of ATB by these cells appeared to require extracellular Na⁺ and was inhibited by ouabain (10^–3 M). Cell suspensions from thyroidectomized rats which have been given three successive doses of T₃ on alternate days (50 g/100 g BW) showed a significant increase in AIB uptake compared with cells isolated from thyroidectomized rats treated with diluent. Efflux of AIB from the cell suspension was not affected by T₃. There was no significant changes in AIB uptake 12 h after a single injection of T₃ (50 g/100 g BW). However, there was a significant 49% and 65% increase in AIB net uptake at 24 and 48 h, respectively, after T₃ treatment. Under similar conditions, the cell suspension showed a 48% increase in NaK-ATPase activity at 12 h and to a peak of 61% at 24 h. Therefore, changes in NaK-ATPase activity preceded the changes in AIB net uptake upon treatment with T₃, implying that AIB uptake is probably mediated, at least in part, by the activity of NaK-ATPase.Abbreviations AIB -Aminoisobutyric acid - HBBS Hank's buffer salt solution - T₃ triiodothyronine This study was supported by NIH grant (AM 28590) and USUHS grant CO 7623     

Cortical and subcortical electrical activity during the development of hypoxia from blood loss

It was shown previously that in some cases during the development of hypoxia polymorphic waves are replaced by synchronous standardized waves, also in the band, which have been called standardized slow complexes (SSC). In the present investigation discharges of the neuron pool were observed during SSC in the caudate nucleus, lateral and medial thalamus, hypothalamus, hippocampus, amygdaloid nucleus, and mesencephalic reticular formation. The highest firing rate of the neurons correlated (P<0.01) with the second half of the negative phase of SSC. Bursts of discharges of the neuron pool during SSC indicate that it reflects physiological processes taking place in these structures.Laboratory of Experimental Physiology of Resuscitation, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. A. Negovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 6, pp. 658–661, June, 1978.     

Activity of enzymes of adenosine metabolism in human natural killer (NK) cells during activation and inhibition of their cytotoxic activity

R. E. Kavetskii Institute for Problems in Oncology, Academy of Sciences of the Ukrainian SSSR, Kiev. Research Institute of Carcinogenesis, All-Union Oncologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. N. Trapeznikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 107, No. 4, pp. 438–440, April, 1989.     

Effect of prolonged physical exercise on fluid regulating hormones

Summary Sixteen well-trained young men performed a test marathon to study the behaviour of atrial natriuretic peptide (ANP) and its second messenger cyclic guanosine monophosphate (cGMP) in relation to changes in plasma volume (PV) and plasma proteins, arginine vasopressin (AVP), renin, aldosterone, potassium and sodium. Blood samples were drawn under standardized conditions before and immediately after the run, as well as 3 h and 31 h after the run. Directly after the run, a two-and-a-half fold increase of plasma ANP and a twofold increase of plasma cGMP level were found, whereas PV decreased significantly by 7.4%. At this time renin-, aldosterone- and AVP-secretion were much stimulated. Thirty-one hours after the run, PV was markedly greater (10%) than before the race, whereas plasma proteins had returned to pre-exercise values. The ANP and cGMP were not significantly altered compared to the pre-race values. We have concluded that ANP and the other volume-regulating hormones may play an important role during and immediately after prolonged physical exercise but not in the longer recovery period. It seems that an influx of plasma proteins into the vascular space is responsible for the increased PV at this time.     

Synchronizing action of cyclic AMP on the mitotic cycle of ehrlich's ascites carcinoma cells

The number of mitoses and of DNA-synthesizing cells in an Ehrlich's ascites carcinoma was studied during the 24 h after injection of dibutyryl cyclic 3,5-adenosine monophosphate. As a result of preprophase inhibition and, probably, of stimulation of entry of the cells into the synthetic period, a large number of cells commences mitosis simultaneously 8 h after the injection. The resulting synchronization of mitosis in the cell population of the tumor is evaluated.Department of General Biology, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 1, pp. 66–68, January, 1976.     

Effect of the dephosphorylated core of 2′,5′-oligoadenylate (2′,5′-ApApA) on electrical activity of the snail neuron

Bulletin of Experimental Biology and Medicine -