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Journal of Hypertension Mar 1992The effects of a brief period of anoxia upon myocardial distensibility and coronary vascular resistance (CVR) were evaluated in two models of pressure overload in the... (Comparative Study)
Comparative Study
OBJECTIVE
The effects of a brief period of anoxia upon myocardial distensibility and coronary vascular resistance (CVR) were evaluated in two models of pressure overload in the rat.
METHODS
A similar degree of left ventricular hypertrophy was obtained by using deoxycorticosterone acetate (DOCA)-salt treatment and abdominal aortic stenosis (AS). The study was performed using an isolated, isovolumic cardiac preparation perfused at a constant coronary flow of approximately 20 ml/min per g left ventricular weight.
RESULTS
In response to a 10-min period of anoxia, hypertrophied hearts manifested an exaggerated decrease in left ventricular diastolic chamber distensibility. Left ventricular diastolic blood pressure (DBP) rose in control, AS and DOCA-salt hearts, with no significant difference between the two hypertrophied groups. The anoxia-induced increase in left ventricular DBP correlated with the left ventricular weight: body weight ratio in all animals, but was higher in the two hypertrophied groups compared with controls when expressed per unit tissue mass. In response to anoxia, CVR increased in both groups of hypertrophied hearts and was correlated with enhanced left ventricular DBP. In addition, CVR increased in proportion to the degree of hypertrophy. Partial correlation analysis showed that this relationship depends upon the level of left ventricular DBP and disappears when this pressure is constant.
CONCLUSION
The anoxia-induced increase in myocardial stiffness is exaggerated in two different models of cardiac hypertrophy. This exaggeration is primarily related to the degree of hypertrophy and results in a more pronounced limitation of the coronary flow in hypertrophied hearts.
Topics: Analysis of Variance; Animals; Aorta, Abdominal; Cardiomegaly; Compliance; Constriction, Pathologic; Coronary Circulation; Desoxycorticosterone; Diastole; Disease Models, Animal; Heart; Heart Ventricles; Hypertension; Hypoxia; Male; Rats; Rats, Inbred Strains
PubMed: 1315819
DOI: 10.1097/00004872-199203000-00005 -
Comptes Rendus Des Seances de La... Jun 1951
Topics: Bradycardia; Humans; Hypoxia
PubMed: 14887137
DOI: No ID Found -
The American Journal of Physiology Feb 1993Most vertebrates have a very limited tolerance to anoxia. The only exceptions to this rule are found among ectothermic species, notably crucian carp (Carassius... (Comparative Study)
Comparative Study
Most vertebrates have a very limited tolerance to anoxia. The only exceptions to this rule are found among ectothermic species, notably crucian carp (Carassius carassius) and freshwater turtles. It has been assumed that the brains of these species are less sensitive to anoxia than ectothermic brains in general. However, it has not been possible to exclude that anoxia-intolerant species like rainbow trout (Oncorhynchus mykiss) die from heart failure rather than brain failure during anoxia, and that the average ectothermic brain is actually rather insensitive to anoxia. By simultaneously measuring the effect of anoxia on brain extracellular K+ activity ([K+]o), blood pressure, and heart rate in rainbow trout, we show that the rainbow trout brain rapidly loses ion homeostasis during anoxia, despite an initial increase in blood pressure. The rainbow trout brain showed a sudden transient increase in [K+]o (suggesting a rapid depolarization) after approximately 30 min of anoxia at 10 degrees C. At the same time the blood pressure was still close to the normoxic value. In a comparative experiment, crucian carp was found to maintain a low brain [K+]o for at least 6 h of anoxia. Thus the results suggest that the rainbow trout brain is anoxia-intolerant in itself, and that its ability to maintain ion gradients during anoxia is very much lower than that of crucian carp. If temperature differences are taken into account, the anoxia sensitivity of the rainbow trout brain is comparable to that of mammals.
Topics: Animals; Blood Pressure; Brain; Carps; Electrocardiography; Extracellular Space; Heart Rate; Hypoxia; Osmolar Concentration; Potassium; Trout
PubMed: 8447481
DOI: 10.1152/ajpregu.1993.264.2.R250 -
Arkhiv Patologii 1953
Topics: Arteries; Humans; Hypoxia; Lung; Pulmonary Artery
PubMed: 13051295
DOI: No ID Found -
Biochimica Et Biophysica Acta. General... Jan 2022The discovery of humanin (HN/MTRNR2) 20 years ago blazed a trail to identifying mitochondrial derived peptides with biological function. (Review)
Review
BACKGROUND
The discovery of humanin (HN/MTRNR2) 20 years ago blazed a trail to identifying mitochondrial derived peptides with biological function.
SCOPE
Humanin is associated with pro-survival, cytoprotective, anti-inflammatory, and anti-oxidative properties and may play a role in reducing neurodegenerative and metabolic disease progression. Although the role of humanin in vitro and in vivo laboratory models is well characterized, the regulation of humanin in natural models that encounter lethal cytotoxic and oxidative insults, as part of their natural history, require immediate research. In this review, we discuss the conservation of humanin-homologues across champion hibernators, anoxia and freeze-tolerant vertebrates and postulate on the putative roles of humanin in non-model species.
SIGNIFICANCE
We hope characterization of humanin in animals that are naturally immune to cellular insults, that are otherwise lethal for non-tolerant species, will elucidate key biomarkers and cytoprotective pathways with therapeutic potential and help differentiate pro-survival mechanisms from cellular consequences of stress.
Topics: Animals; Cold-Shock Response; Hibernation; Humans; Hypoxia; Intracellular Signaling Peptides and Proteins; Nervous System Physiological Phenomena; Stress, Physiological
PubMed: 34626747
DOI: 10.1016/j.bbagen.2021.130022 -
A.M.A. Archives of Otolaryngology Jul 1954
Topics: Humans; Hypoxia; Trachea; Tracheotomy
PubMed: 13170890
DOI: 10.1001/archotol.1954.00720010004001 -
The American Journal of Physiology Dec 1996The turtle heart provides a model system to study the effects of anoxia on protein synthesis without the potentially confounding factor of contractile failure and...
The turtle heart provides a model system to study the effects of anoxia on protein synthesis without the potentially confounding factor of contractile failure and decreased ATP levels. Protein synthesis, as measured by 3H-labeled phenylalanine incorporation, was studied under conditions of normoxia and anoxia in isolated perfused turtle [Trachemys (= Pseudemys) scripta elegans] hearts at 15 degrees C. Heart rate, cardiac output, and ventricular pressure development were unaffected by 2 or 3 h of anoxia. Despite the anoxia, energy levels in the heart were presumably still high, since contractility was maintained. RNA content of ventricle decreased after anoxic perfusion. Rates of total protein synthesis rates in ventricle were threefold lower under anoxia than under normoxia. These findings suggest that the total level of RNA is one determinant of protein synthesis. Incorporation of label into protein extracted from mitochondria was also assessed. The ratio of mitochondrial to whole ventricular protein synthesis was significantly lower after anoxia, revealing preferential control mechanisms under anoxia between the synthesis of total cellular protein and protein destined for mitochondria. Isolated mitochondria were still coupled after 2 or 3 h of anoxia. In effect, the mitochondria enter into a state of hypometabolism in terms of rates of ATP synthesis and protein synthesis, but functional integrity is maintained. The decrease in protein synthesis in general and mitochondrial protein synthesis in particular may represent an adaptation to allow the partitioning of the available energy resources toward mechanical function during anoxia.
Topics: Animals; Enzymes; Female; Heart; Heart Ventricles; Hypoxia; Male; Mitochondria, Heart; Myocardium; Oxygen Consumption; Phenylalanine; Protein Biosynthesis; RNA; Turtles
PubMed: 8997367
DOI: 10.1152/ajpregu.1996.271.6.R1660 -
Journal of Neuroscience Methods May 2011Neonatal anoxia is a worldwide clinical problem that has serious and lasting consequences. The diversity of models does not allow complete reproducibility, so a...
Neonatal anoxia is a worldwide clinical problem that has serious and lasting consequences. The diversity of models does not allow complete reproducibility, so a standardized model is needed. In this study, we developed a rat model of neonatal anoxia that utilizes a semi-hermetic system suitable for oxygen deprivation. The validity of this model was confirmed using pulse oximetry, arterial gasometry, observation of skin color and behavior and analysis of Fos immunoreactivity in brain regions that function in respiratory control. For these experiments, 87 male albino neonate rats (Rattus norvegicus, lineage Wistar) aged approximate 30 postnatal hours were divided into anoxia and control groups. The pups were kept in an euthanasia polycarbonate chamber at 36±1 °C, with continuous 100% nitrogen gas flow at 3 L/min and 101.7 kPa for 25 min. The peripheral arterial oxygen saturation of the anoxia group decreased 75% from its initial value. Decreased pH and partial pressure of oxygen and increased partial pressure of carbon dioxide were observed in this group, indicating metabolic acidosis, hypoxia and hypercapnia, respectively. Analysis of neuronal activation showed Fos immunoreactivity in the solitary tract nucleus, the lateral reticular nucleus and the area postrema, confirming that those conditions activated areas related to respiratory control in the nervous system. Therefore, the proposed model of neonatal anoxia allows standardization and precise control of the anoxic condition, which should be of great value in indentifying both the mechanisms underlying neonatal anoxia and novel therapeutic strategies to combat or prevent this widespread public health problem.
Topics: Animals; Animals, Newborn; Arteries; Blood Gas Analysis; Disease Models, Animal; Hemoglobins; Hypoxia; Male; Motor Activity; Oncogene Proteins v-fos; Oxygen; Partial Pressure; Rats; Rats, Wistar; Respiration; Reticular Formation; Skin
PubMed: 21439321
DOI: 10.1016/j.jneumeth.2011.03.009 -
The American Journal of Physiology Dec 1992To investigate mechanisms of cerebral anoxia tolerance, cerebrocortical intracellular calcium ([Ca2+]i) and pH (pHi) regulation were compared in turtles (Trachemys...
To investigate mechanisms of cerebral anoxia tolerance, cerebrocortical intracellular calcium ([Ca2+]i) and pH (pHi) regulation were compared in turtles (Trachemys scripta) and laboratory rats. [Ca2+]i and pHi in living 200 to 300-microns-thick cortical brain slices were measured with the fluorescent indicators fura-2/acetoxymethyl ester (AM) and 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein during exposure to anoxia. Within 5 min, [Ca2+]i increased to > 1,000 nM in rat brain slices exposed to anoxia but [Ca2+]i was normal even after 5 h of anoxia in turtles. ATP levels remained normal in anoxic turtle brain but fell rapidly in rats. During anoxia, pHi fell by 0.25 +/- 0.08 pH units in rats but only 0.10 +/- 0.04 in turtles (P < 0.05). Inhibition of glycolysis in anoxic turtle brain with iodoacetate resulted in large increases in [Ca2+]i but prior exposure of slices to anoxia resulted in greatly attenuated calcium entry. The reduction in calcium flux was greater with increasing exposure to anoxia, suggesting progressive arrest of calcium channel activity. Tolerance of cerebral anoxia in turtles may be related to anaerobic ATP production, arrest of calcium channels, and attenuation of changes in pHi.
Topics: Adenosine Triphosphate; Animals; Brain; Calcium; Hydrogen-Ion Concentration; Hypoxia; Intracellular Membranes; Rats; Rats, Sprague-Dawley; Turtles
PubMed: 1481942
DOI: 10.1152/ajpregu.1992.263.6.R1298 -
Food Chemistry Aug 2017The effects of short-term anoxia exposure for 16h on physicochemical changes of 'Phulae' pineapple fruit stored at ambient temperature (25±2°C) were investigated. The...
The effects of short-term anoxia exposure for 16h on physicochemical changes of 'Phulae' pineapple fruit stored at ambient temperature (25±2°C) were investigated. The respiratory rate of the fruit was induced by the anoxia treatment. However, it retarded the increase in moisture loss and maintained both flesh and pulp colour by inhibiting polyphenol oxidase (PPO) activity of the both tissues. The anoxia exposure delayed the increase in total sugar content and enhanced total ascorbic acid content during storage. The half-cut pineapple fruit showed that the anoxia exposure completely inhibited internal transparency of the flesh tissue adjacent to core during the storage. In conclusion, the short-term anoxia exposure for 16h maintained postharvest quality, retarded physiological disorder and enhanced nutritional values of the pineapple fruit stored at ambient temperature (25±2°C).
Topics: Ananas; Food Storage; Fruit; Hypoxia
PubMed: 28317739
DOI: 10.1016/j.foodchem.2017.02.028