scholarly journals Effect of Acute Arterial Hypo- and Hypertension on Cerebrocortical NAD/NADH Redox State and Vascular Volume

1982 ◽  
Vol 2 (2) ◽  
pp. 209-219 ◽  
Author(s):  
Eörs Dóra ◽  
Arisztid G. B. Kovách
Keyword(s):  
Redox State ◽  
Arterial Hypotension ◽  
Minor Role ◽  
Vascular Volume ◽  
Fluorescence Measurements ◽  
Arterial Blood ◽  
Nadh Fluorescence ◽  
Alpha Receptors ◽  
A Minor ◽  
Nadh Redox State

The effects of stepwise arterial hypotension (MABP: 80, 60, 40 mm Hg) and moderate arterial hypo- and hypertension (MABP: 80, 150–160 mm Hg) on cerebrocortical vascular volume and NAD/NADH redox state were studied in anaesthetized cats, The vascular volume and NADH fluorescence measurements were performed on closed skull preparations using a microscope fluororeflectometer. To determine the possible role of adrenergic alpha-receptors in the autoregulatory adjustment of cerebrocortical vascular volume, some of the animals were pretreated with intra-arterially infused phenoxybenzamine (1 mg/kg), It was found that longlasting stepwise arterial hypotension leads to a gradual increase in cerebrocortical vascular volume and NADH fluorescence, Though the cerebrocortical arteries dilatated considerably at 80 mm Hg, sustained for 30 min, the NAD/NADH redox state failed to be reoxidized but was shifted to a more reduced state. This finding suggests that some factor other than tissue hypoxia is responsible for the dilatation of cerebrocortical vessels during moderate arterial hypotension. When the arterial blood pressure was restored following stepwise arterial hypotension, the cerebrocortical vascular volume did not decrease and the NAD/NADH redox state remained reduced, showing that the autoregulatory capability of the vessels was lost and the tissue metabolism was irreversibly altered. During a 5-min duration of moderate arterial hypo- and hypertension, biphasic changes were obtained in cerebrocortical vascular volume while the NAD/NADH redox state was shifted to a more reduced and oxidized state. Since the dilatation and the constriction of the cerebrocortical vessels during arterial hypo- and hypertension lagged by 40–80 s behind the redox state alterations, it is suggested that the myogenic mechanism has a minor role in CBF autoregulation. Phenoxybenzamine (PBZ) dilatated the cerebrocortical vessels, indicating the existence of an active alpha-receptor-mediated vasoconstrictory tone. Since the extent of autoregulatory vascular volume changes was not affected by PBZ pretreatment, the involvement of adrenergic alpha-receptors in the autoregulation of CBF can be excluded, at least for cats.

Control hof the hyperglycemic response to hemorrhage in cats

1982 ◽  
Vol 60 (12) ◽  
pp. 1618-1623 ◽  
Author(s):  
W. Wayne Lautt ◽  
Peter D. Dwan ◽  
Rajiva R. Singh
Keyword(s):  
Sympathetic Nerves ◽  
Minor Role ◽  
Hepatic Glycogen ◽  
Hormonal Changes ◽  
Direct Stimulation ◽  
Glucose Levels ◽  
Arterial Blood ◽  
Blood Glucose Levels ◽  
6 Hydroxydopamine ◽  
A Minor

Rapid hemorrhage to 50 mmHg (1 mmHg = 133.322 Pa) mean arterial blood pressure led to a rise in blood glucose levels that reached a level of 500 mg% by 15 min and was then maintained with minor decreases for the full period of hemorrhage (90 min). From changes in hepatic glycogen levels it is estimated that glucose from 3.1 g of glycogen was released per kilogram of body weight over the 90-min period of hemorrhage. Bilateral adrenalectomy or hepatic denervation did not reduce the hyperglycemic response significantly although adrenalectomy tended to produce a lesser response. Removal of the adrenals and the hepatic nerves (surgically or selective hepatic sympathectomy using 6-hydroxydopamine) eliminated all but a very small hyperglycemic response which was of slow onset. Thus, the hyperglycemic response to hemorrhage is controlled by a redundant control system wherein either the adrenals or the hepatic sympathetic nerves can produce the response but elimination of both systems eliminates the response. The minor hyperglycemia that occurred with both systems eliminated shows that other hormonal changes known to occur during hemorrhage play, at most, a minor role in the direct stimulation of glycogenosis during hemorrhage.

scholarly journals Effect of the Organic Calcium Antagonist D-600 on Cerebrocortical Vascular and Redox Responses Evoked by Adenosine, Anoxia, and Epilepsy

1983 ◽  
Vol 3 (1) ◽  
pp. 51-61 ◽  
Author(s):  
Arisztid G. B. Kovách ◽  
Eörs Dóra ◽  
Sándor Szedlacsek ◽  
Ákos Koller
Keyword(s):  
Calcium Ions ◽  
Calcium Antagonists ◽  
Redox State ◽  
Brain Cortex ◽  
Calcium Influx ◽  
Epileptic Seizures ◽  
Metabolic Effects ◽  
Minor Role ◽  
The Brain ◽  
Nadh Redox State

The purpose of this study was to investigate the role of calcium ions in cerebrocortical vasodilatation and oxidized and reduced nicotinamide adenine dinucleotide (NAD/NADH) redox responses evoked by adenosine, anoxia, and epileptic seizures. The brain cortex of chloralose-anaesthetized cats was treated locally with gallopamil-hydrochloride (D-600) and verapamil (Isoptin®). These organic calcium antagonists decrease the inward movement of calcium ions into vascular smooth muscle cells. Cerebrocortical vascular volume (CVV) and NADH fluorescence were measured in vivo by fluororeflectometry. Adenosine and calcium antagonists were dissolved in artificial cerebrospinal fluid (mock CSF) and applied topically to the brain cortex by superfusion. Adenosine (10−8 to 10−3 M) resulted in concentration-dependent increases in CVV. The NAD/NADH redox state was not altered below adenosine concentrations of 10−5 M. However, in the concentration range of 10−5 to 10−3 M, significant NAD reduction was obtained. Both calcium antagonists increased CVV markedly, but did not bring about significant changes in NAD/NADH ratio and local electrical activity of the exposed brain cortex. D-600 (2 × 10−6 M) increased CVV as much as did 10−4 M adenosine, but it failed to diminish the vascular and metabolic effects of the adenosine. D-600 (2 × 10−4 M) resulted in an increase in CVV approximately 2.5 times greater than that caused by 10−4 M adenosine alone. However, the adenosine-induced CVV response was inhibited by only about 70%, compared with the control response. After pretreating the brain cortex with 2 × 10−3 M D-600, adenosine had no effects on CVV and NAD/NADH redox state; the NAD reduction accompanying anoxia and epileptic seizures was considerably diminished. These results suggest that the inhibition of transmembrane calcium influx could have a minor role in the vasodilatatory mechanism of adenosine. Since the vascular effect of adenosine vanished only at very high concentration of D-600, which might also inhibit the release of calcium from intracellular binding sites, it is presumed that adenosine dilates the cerebrocortical vessels by interacting with intracellular calcium-sequestrating mechanisms. Furthermore, since adenosine had a marked NAD reducing effect and since it is well known that it increases the activity of adenylate cyclase and phosphorylase enzymes, accumulation of 3′,5′-cyclic adenosine monophosphate (cAMP) and substrate mobilization might be involved also in the vasodilatatory mechanism of adenosine. Our results concerning the inhibitory effect of D-600 on epilepsy- and anoxia-induced cerebrocortical NAD reduction unambiguously demonstrate the significance of calcium fluxes in glycogen and glucose metabolism under these conditions.

Intrapulmonary Co2 receptors and ventilatory response to lung Co2 loading

1982 ◽  
Vol 52 (5) ◽  
pp. 1272-1277 ◽  
Author(s):  
R. D. Tallman ◽  
F. S. Grodins
Keyword(s):  
Venous Blood ◽  
Co2 Flux ◽  
Minor Role ◽  
Arterial Blood Gas ◽  
Co2 Partial Pressure ◽  
Blood Oxygenator ◽  
Arterial Blood ◽  
Significant Difference ◽  
Pattern Determination ◽  
A Minor

The possible role of intrapulmonary CO2 receptors (IPC) in arterial CO2 partial pressure (PaCO2) homeostasis was investigated by comparing the arterial blood gas and ventilatory responses to CO2 loading via the inspired gas and via the venous blood. Adult male Pekin ducks were decerebrated 1 wk prior to an experiment. Venous CO2 loading was accomplished with a venovenous extracorporeal blood circuit that included a silicone-membrane blood oxygenator. The protocol randomized four states: control (no loading), venous CO2 loading, inspired CO2 loading, and venous CO2 unloading. Intravenous and inspired loading both resulted in hypercapnic hyperpnea. Comparison of the ventilatory sensitivity (delta VE/delta PaCO2) showed no significant difference between the two loading regimes. Likewise, venous CO2 unloading led to a significant hypocapnic hypopnea. Sensitivity to changes in PaCO2 could explain the response of ventilation under these conditions. The ventilatory pattern, however, was differentially sensitive to the route of CO2 loading; inspired CO2 resulted in slower deeper breathing than venous loading. It is concluded that IPC play a minor role in adjusting ventilation to match changes in pulmonary CO2 flux but rather are involved in pattern determination.

scholarly journals Effect of Topically Administered Epinephrine, Norepinephrine, and Acetylcholine on Cerebrocortical Circulation and the NAD/NADH Redox State

1983 ◽  
Vol 3 (2) ◽  
pp. 161-169 ◽  
Author(s):  
Eörs Dóra ◽  
Arisztid G. B. Kovách
Keyword(s):  
Redox State ◽  
Synaptic Cleft ◽  
Nadh Oxidation ◽  
Tissue Respiration ◽  
Pial Arteries ◽  
Cranial Window ◽  
Pial Vessels ◽  
Nadh Fluorescence ◽  
The Brain ◽  
Nadh Redox State

We investigated the effects of topically administered catecholamines and acetylcholine (ACh) on the cerebrocortical microcirculation and NAD/NADH redox state in chloralose-anesthetized cats. NADH fluorescence of the brain cortex and the volume of small intracortical vessels were measured by fluororeflectometry, and in most of the experiments the pial vessels were photographed simultaneously through a cranial window. Cerebrocortical vascular volume (CVV) and the diameter of the pial vessels were decreased, and NADH was oxidized by concentrations of epinephrine and norepinephrine as low as 3 × 10−8 M. Pial veins constricted approximately twice as much as pial arteries. ACh dilatated pial arteries, slightly constricted pial veins, and increased CVV, but had no effect on the NAD/NADH redox state. Since pial and intracortical vessels were constricted markedly by catecholamines, and since these vascular reactions appeared at a lower concentration than is presumed to occur in the synaptic cleft, our results support the regulating role of these substances in cerebral circulation. NADH oxidation, obtained with catecholamines, was interpreted to be due to enhanced tissue respiration. The finding that ACh dilatated pial arteries and increased CVV, but failed to influence the NAD/NADH redox state, might indicate that the brain cortices of normal animals are bioenergetically nonhypoxic. If cortical microregions where the oxygen tension is close to zero were biochemically hypoxic, NADH oxidation should have occurred during ACh administration.

The Effect of Path Length and Display Size on Memory for Spatial Information

2012 ◽  
Vol 59 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Katherine Guérard ◽  
Sébastien Tremblay
Keyword(s):  
Path Length ◽  
Potential Role ◽  
Spatial Information ◽  
Recall Performance ◽  
Minor Role ◽  
Length Effect ◽  
Serial Memory ◽  
Fixed Reference ◽  
A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

Use of Different Tissue Thromboplastins in the Control of Anticoagulant-Therapy

1958 ◽  
Vol 02 (05/06) ◽  
pp. 462-480 ◽  
Author(s):  
Marc Verstraete ◽  
Patricia A. Clark ◽  
Irving S. Wright
Keyword(s):  
Prothrombin Time ◽  
Anticoagulant Therapy ◽  
Factor Vii ◽  
Rabbit Brain ◽  
Minor Role ◽  
Rabbit Lung ◽  
Coagulation Mechanism ◽  
Time Test ◽  
The One ◽  
A Minor

SummaryAn analysis of the results of prothrombin time tests with different types of thromboplastins sheds some light on the problem why the administration of coumarin is difficult to standardize in different centers. Our present ideas on the subject, based on experimental data may be summarized as follows.Several factors of the clotting mechanism are influenced by coumarin derivatives. The action of some of these factors is by-passed in the 1-stage prothrombin time test. The decrease of the prothrombin and factor VII levels may be evaluated in the 1-stage prothrombin time determination (Quick-test). The prolongation of the prothrombin times are, however, predominantly due to the decrease of factor VII activity, the prothrombin content remaining around 50 per cent of normal during an adequate anticoagulant therapy. It is unlikely that this degree of depression of prothrombin is of major significance in interfering with the coagulation mechanism in the protection against thromboembolism. It may, however, play a minor role, which has yet to be evaluated quantitatively. An exact evaluation of factor VII is, therefore, important for the guidance of anticoagulant therapy and the method of choice is the one which is most sensitive to changes in factor VII concentration. The 1-stage prothrombin time test with a rabbit lung thromboplastin seems the most suitable method because rabbit brain preparations exhibit a factor VII-like activity that is not present in rabbit lung preparations.

Produktivkraft als Versprechen

2016 ◽  
Vol 46 (185) ◽  
pp. 621-638 ◽  
Author(s):  
Christian Siefkes
Keyword(s):  
Private Consumption ◽  
Minor Role ◽  
Progressive Reduction ◽  
Internal Forces ◽  
A Minor

The ‘Fragment on Machines’ from Marx’s Grundrisse is often cited as an argument that the internal forces of capitalism will lead to its doom. But the argument that the progressive reduction of labor must doom capitalism lacks a proper foundation, as a comparison with the ‘Schemes of Reproduction’ given in Capital II shows. The latter, however, aren’t fully convincing either. In reality, more depends on the private consumption of capitalists than either model recognizes. Ultimately, most can be made of the ‘Fragment on Machines’ by reading it not as an exposure of capitalism’s internal contractions, but as a discussion of a possible communist future where labor (or work) will play but a minor role.

Effects of Myo-inositol Alone and in Combination with Seleno-Lmethionine on Cadmium-Induced Testicular Damage in Mice

2019 ◽  
Vol 12 (4) ◽  
pp. 311-323 ◽  
Author(s):  
Salvatore Benvenga ◽  
Antonio Micali ◽  
Giovanni Pallio ◽  
Roberto Vita ◽  
Consuelo Malta ◽  
...  
Keyword(s):  
Structural Changes ◽  
Natural Antioxidants ◽  
Minor Role ◽  
Positive Role ◽  
Testosterone Levels ◽  
Tnf Α ◽  
Testicular Lesions ◽  
A Minor ◽  
Immunohistochemical Analyses

Background: Cadmium (Cd) impairs gametogenesis and damages the blood-testis barrier. Objective: As the primary mechanism of Cd-induced damage is oxidative stress, the effects of two natural antioxidants, myo-inositol (MI) and seleno-L-methionine (Se), were evaluated in mice testes. Methods: Eighty-four male C57 BL/6J mice were divided into twelve groups: 0.9% NaCl (vehicle; 1 ml/kg/day i.p.); Se (0.2 mg/kg/day per os); Se (0.4 mg/kg/day per os); MI (360 mg/kg/day per os); MI plus Se (0.2 mg/kg/day); MI plus Se (0.4 mg/kg/day); CdCl2 (2 mg/kg/day i.p.) plus vehicle; CdCl2 plus MI; CdCl2 plus Se (0.2 mg/kg/day); CdCl2 plus Se (0.4 mg/kg/day); CdCl2 plus MI plus Se (0.2 mg/kg/day); and CdCl2 plus MI plus Se (0.4 mg/kg/day). After 14 days, testes were processed for biochemical, structural and immunohistochemical analyses. Results: CdCl2 increased iNOS and TNF-α expression and Malondialdehyde (MDA) levels, lowered glutathione (GSH) and testosterone, induced testicular lesions, and almost eliminated claudin-11 immunoreactivity. Se administration at 0.2 or 0.4 mg/kg significantly reduced iNOS and TNF-α expression, maintained GSH, MDA and testosterone levels, structural changes and low claudin-11 immunoreactivity. MI alone or associated with Se at 0.2 or 0.4 mg/kg significantly reduced iNOS and TNF-α expression and MDA levels, increased GSH and testosterone levels, ameliorated structural organization and increased claudin-11 patches number. Conclusion: We demonstrated a protective effect of MI, a minor role of Se and an evident positive role of the association between MI and Se on Cd-induced damages of the testis. MI alone or associated with Se might protect testes in subjects exposed to toxicants, at least to those with behavior similar to Cd.

Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

1985 ◽  
Vol 50 (3) ◽  
pp. 581-599 ◽  
Author(s):  
Petr Vaňura ◽  
Emanuel Makrlík
Keyword(s):  
Stability Constants ◽  
Organic Phase ◽  
Equilibrium Constants ◽  
Minor Role ◽  
Nitrobenzene Solution ◽  
Ligand Structure ◽  
Stability Constants Of Complexes ◽  
Separation Factors ◽  
The Stability ◽  
A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

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