RESUMO
Adaptive changes in energy metabolism, as reflected by pyruvate kinase and cytochrome oxidase activities, were examined during in vitro differentiation of the cultivated macrophage. Serum concentrations of tissue culture media, which directly influence endocytic activity, and ambient oxygen tension were both shown to influence pyruvate kinase and cytochrome oxidase activities. Cells maintained in high serum concentrations (30% newborn calf serum [NBCS]) exhibited a 300-400% increase in pyruvate kinase activity and a 40% increase in cytochrome oxidase activity, whereas cells maintained in low serum concentrations (2% NBCS) exhibited a lesser increase (65%) in pyruvate kinase activity and no change in cytochrome oxidase activity. Anaerobiosis resulted in additional alterations in pyruvate kinase and cytochrome oxidase activities. Cells maintained for 48-72 h under anaerobic conditions exhibited a 500-600% increase in pyruvate kinase activity and a 40% decrease in cytochrome oxidase activity. Increased pyruvate kinase activity was dependent on continued protein synthesis. Enzyme increases occurred in anaerobically cultured cells despite an overall reduction in cell protein synthesis. It is suggested that adaptive changes in pyruvate kinase and cytochrome oxidase activity resulting from alterations in either serum concentration or ambient oxygen tension are regulated by two independent mechanisms. One mechanism is aimed at providing energy for endocytic activity and the other in compensating for impaired oxidative metabolism during anaerobiosis.
Assuntos
Diferenciação Celular , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Metabolismo Energético , Macrófagos/enzimologia , Monócitos/enzimologia , Piruvato Quinase/metabolismo , Aerobiose , Anaerobiose , Animais , Células Cultivadas , Meios de Cultura , Cicloeximida/farmacologia , Masculino , Camundongos , Consumo de Oxigênio , Fagócitos/enzimologia , Biossíntese de ProteínasRESUMO
Alveolar macrophages acquired the capacity to oxidize uric acid after exposure to uricase. Presumably this resulted from intracellular incorporation of the enzyme by endocytosis. This approach may provide a general method for (i) testing regulatory biochemical mechanisms, (ii) therapeutic replacement of deficient regulatory macromolecules, and (iii) studying environmental factors that produce genetic alterations.
Assuntos
Macrófagos/enzimologia , Urato Oxidase/metabolismo , Animais , Antimicina A/farmacologia , Endocitose , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Macrófagos/fisiologia , Alvéolos Pulmonares/citologia , Coelhos , Ácido Úrico/metabolismoRESUMO
The effects of intracellular edema and dehydration on energy metabolism in alveolar macrophages were studied. Intracellular edema increased lactate production and reversibly decreased oxygen consumption. Dehydration caused no significant change in lactate production but irreversibly decreased oxygen consumption. These phenomena may be applicable to a wide variety of clinical problems including lung and brain edema.
Assuntos
Desidratação/metabolismo , Edema/metabolismo , Metabolismo Energético , Macrófagos/metabolismo , Animais , Lactatos/biossíntese , Concentração Osmolar , Consumo de Oxigênio , Alvéolos Pulmonares , CoelhosRESUMO
Saline washings obtained in vivo from the lung of young calves produce pulmonary hypertension upon intrayascular (systemic or pulmonary) injection into either the dog or the calf. This pulmonary hypertension is produced by vasoconstriction of small, precapillary pulmonary vessels. The active agent, pulmonary arterial constrictor substance, differs chemically and physiologically from other substances which have been investigated with respect to vasomotor activity in the pulmonary circulation. Although the chemical nature of the active agent is not known it appears to have a relatively large molecular weight. Whether this agent plays a role in the physiological regulation of the pulmonary circulation is not known.
Assuntos
Hipertensão Pulmonar , Artéria Pulmonar , Vasoconstritores/farmacologia , Vasoconstritores/fisiologia , Angiografia , Animais , Débito Cardíaco , Bovinos , Cães , Hemodinâmica , Circulação Pulmonar , Resistência VascularRESUMO
The effect of hypoxic exposure on various mitochondrial enzymes and on cell mitochondrial genomic content was studied in two types of mammalian cells. Hypoxia depressed the activity of six enzymes to the same degree. The kinetics of depression and of recovery during reexposure to normoxia were statistically similar for three marker enzymes. Despite the global and symmetrical decrease in enzyme activities, mitochondrial DNA remained constant. This suggests either symmetrical loss of mitochondrial enzymes from all mitochondria or complete loss of enzymes from a subpopulation of mitochondria with retention of an intact mitochondrial genome.
Assuntos
Citrato (si)-Sintase/metabolismo , DNA Mitocondrial/genética , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Macrófagos/enzimologia , Mitocôndrias Musculares/enzimologia , Mitocôndrias/enzimologia , Oxirredutases/metabolismo , Oxo-Ácido-Liases/metabolismo , Aerobiose , Anaerobiose , Animais , Citrato (si)-Sintase/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Hipóxia/fisiopatologia , Camundongos , Oxirredutases/genética , RatosRESUMO
Angiograms were obtained in the harbor seal, Phoca vitulina, in air and during diving. During diving there is arterial constriction of the vascular beds of muscle, skin, kidney, liver, spleen, and presumably of all vascular beds except those perfusing the brain and heart. There is sudden constriction and narrowing of muscular arteries close to their origin from the aorta. Constriction of small arterial branches is so intense that blood flow is essentially lost in all involved organs.
Assuntos
Artérias/fisiologia , Carnívoros/fisiologia , Mergulho , Angiografia , Animais , Eletrocardiografia , Frequência Cardíaca/fisiologiaRESUMO
Bradycardia associated with diving in the harbor seal has been dissociated from the arterial constrictor response by intracardiac pacing. Development of arterial constriction does not depend upon the development of bradycardia. During pacing, arterial constriction continues in the absence of bradycardia. Increases in heart rate to values greater than 120 beats per minute during a dive produce a progressive decrease in mean aortic pressure, which suggests that one major function of bradycardia is to reduce cardiac output, thus matching left ventricular output to the restricted vascular bed and decreased venous return associated with diving.
Assuntos
Artérias/fisiopatologia , Bradicardia/fisiopatologia , Caniformia/fisiologia , Mergulho , Animais , Aorta/fisiopatologia , Pressão Sanguínea , Cateterismo Cardíaco , Débito Cardíaco , Constrição , Feminino , Frequência Cardíaca , Marca-Passo ArtificialRESUMO
Cytoplasmic free NAD(+)/NADH ratios have been calculated from lactate to pyruvate ratios, and mitochondrial NAD(+)/NADH ratios, have been calculated from beta-hydroxybutyrate to acetoacetate ratios in isolated rabbit alveolar macrophages. In freshly harvested cells, assuming a pH of 7 for the two compartments, cytoplasmic NAD(+)/NADH averaged 709 +/-293 (SD), and mitochondrial NAD(+)/NADH averaged 33.2 +/-30.2, values which are significantly different. 30 min of air incubation in a relatively poorly buffered medium showed a significant reduction in calculated mitochondrial NAD(+)/NADH to 10.1 +/-4.8. 30 min of exposure of cells to a hypoxic environment (equivalent to a nonventilated, perfused alveolus) caused significant reductions of NAD(+)/NADH in both compartments. Re-exposure of hypoxic cells to air produced a change toward normal in cytoplasmic NAD(+)/NADH but did not reverse mitochondrial abnormality. Uncertainties concerning the value of cytoplasmic and mitochondrial pH under control conditions and during experimental pertubations, limit absolute interpretation of NAD(+)/NADH ratios calculated from redox pairs, but the data suggest the following: (a) separate cytoplasmic and mitochondrial compartments for NAD(+) and NADH exist in the alveolar macrophage; (b) brief periods of exposure to moderate hypoxia of the degree seen in clinical lung disease produce decreases in both cytoplasmic and mitochondrial NAD(+)/NADH; (c) the mitochondrial changes are less easily reversed than the cytoplasmic changes; (d) measurements of NAD(+)/NADH provide an early sensitive indication of biochemical abnormality; and (e) careful control of extracellular pH is required in studies involving experimental modifications of alveolar macrophage function.
Assuntos
Citoplasma/metabolismo , Macrófagos/metabolismo , Mitocôndrias/metabolismo , NAD/metabolismo , Oxirredução , Alvéolos Pulmonares/metabolismo , Animais , Feminino , Concentração de Íons de Hidrogênio , Hipóxia/metabolismo , Técnicas In Vitro , Lactatos/metabolismo , Masculino , Perfusão , Alvéolos Pulmonares/citologia , Piruvatos/biossíntese , CoelhosRESUMO
The bioenergetic pattern of a cell clone derived from rat lung with ultrastructural and biochemical characteristics like those of type II pneumocytes (T-II-P), has been studied in a tissue culture system. During air cultivation, these cells have a high rate of aerobic and anaerobic glycolysis associated with high activities of two rate-limiting enzymes in glycolysis (pyruvate kinase [PyKi] and phosphofructokinase [PFK]). This is present despite the rates of oxygen consumption and activities of cytochrome oxidase (CyOx) similar to other lung cells. Presumably the high rate of aerobic glycolysis explains the substantial lactate production previously described in lung slices and in the intact perfused lung. Hypoxic cultivation results in a decrease in CyOx. Acute re-exposure to air does not restore the oxygen consumption to normal, presumably as a result of decreased mitochondrial O(2) utilization associated with decreased CyOx activity. As a result, hypoxically cultivated T-II-P cells have a decreased capacity for mitochondrial ATP generation in air as compared to air-cultivated cells. During hypoxia, aerobic and anaerobic glycolysis are further increased as well as the activities of PyKi and PFK. The high rate of glycolysis and high activities of PyKi and PFK in cultivated T-II-P appear to reflect intrinsic genetic regulation. The decreased CyOx activity and increased PyKi and PFK activities in hypoxic T-II-P appear to reflect alterations in enzyme biosynthesis/biodegradation regulated by O(2) availability.
Assuntos
Glicólise , Consumo de Oxigênio , Alvéolos Pulmonares/metabolismo , Animais , Linhagem Celular , Células Clonais/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Hipóxia/metabolismo , Fosfofrutoquinase-1/metabolismo , Alvéolos Pulmonares/citologia , Piruvato Quinase/metabolismo , RatosRESUMO
Previously reported changes in static lung volumes during pregnancy have been confirmed. Measurements of lung compliance (C(L)) and total pulmonary resistance (R(L)) were made in 10 women in the last trimester of pregnancy and 2 months postpartum, employing an esophageal balloon and recording spirometer. C(L) was unaffected by pregnancy, but R(L) was 50% below normal during pregnancy. Measurements of airway conductance (C(A)) were made, employing the constant pressure body plethysmograph on 14 nonpregnant and 13 pregnant women. Specific airway conductance was increased during pregnancy. Serial measurements of C(A) indicated a progressive increase beginning at about 6 months of gestation and a return to normal by 2 months postpartum. The mechanism of the increased C(A) during pregnancy is not known. It may be related to changes in bronchial smooth muscle tone and conceivably explains the tolerance of certain patients with lung resections to pregnancy.
Assuntos
Gravidez/fisiologia , Respiração/fisiologia , Adolescente , Adulto , Dispneia , Feminino , Humanos , Pletismografia , Pressão , EspirometriaRESUMO
Monoclonal antibodies were prepared against pyruvate kinase (PyKi; ATP: pyruvate phosphotransferase, EC 2.7.1.40) and used to quantitate PyKi content in L2 lung cells and WI-38 fibroblasts cultivated under hypoxic and normoxic conditions. After 96 h of hypoxic cultivation, PyKi activity was significantly increased in both cell types (L2: normoxia [Po2 = 142 torr], 0.11 +/- 0.01 [SD]; hypoxia [Po2 = 14 torr], 0.25 +/- 0.04 U/microgram DNA, P < 0.01). PyKi content increased proportionately in both cell lines (L2: normoxia, 0.44 +/- 0.13; hypoxia, 0.94 +/- 0.13 microgram enzyme protein/microgram DNA). Specific activity was not significantly different after 96 h (L2: normoxia, 261 +/- 11; hypoxia, 261 +/- 14 U/mg enzyme protein). These results indicate that regulation of glycolysis during chronic hypoxia occurs at the level of enzyme content. Chronic O2 depletion leads to either an increased rate of biosynthesis or a decreased rate of biodegradation of PyKi, causing augmented glycolytic capacity. Monoclonal antibodies provide a highly specific, convenient approach to charcterizing enzymes, as well as quantitating cellular enzyme content.
Assuntos
Anticorpos , Glicólise , Hipóxia/enzimologia , Piruvato Quinase/metabolismo , Animais , Células Cultivadas , Células Clonais/imunologia , Células Híbridas/imunologia , Isoenzimas/metabolismo , Cinética , Pulmão/metabolismo , Piruvato Quinase/imunologia , RatosRESUMO
A method is described for the measurement of total body exchangeable oxygen stores (TBO(2)). It is based on the dilution of the stable oxygen isotope, (18)O(2), by the body exchangeable oxygen stores under circumstances in which (18)O(2) steady-state equilibrium was evaluated simultaneously for both arterial and venous blood compartments. After evaluation of several simplifying assumptions, TBO(2) values in dog, normal man, and anemic patients were measured. The magnitude of the exchangeable nonlung oxygen stores was 11.0 +/- 3.1 ml/kg (SD) in 5 dogs, 11.9 +/- 2.1 ml/kg in 10 normal subjects, and 7.0 +/- 1.6 ml/kg in 8 patients with severe anemia (hematocrits of 25% or less).
Assuntos
Oxigênio/metabolismo , Anemia/fisiopatologia , Animais , Cães , Humanos , Pulmão/fisiologia , Masculino , Métodos , Oxigênio/sangue , Consumo de Oxigênio , Isótopos de Oxigênio , Técnica de Diluição de RadioisótoposRESUMO
Alveolar macrophages (AM) and peritoneal macrophages (PM) originate from common precursor cells, but function in different O2 environments. In the present studies, the impact of different O2 tensions on cell metabolism has been quantitatively determined, an enzymatic basis for these differences established, and a mechanism which regulates enzymatic differences demonstrated. O2 consumption and lactate production were compared in rabbit AM and PM in air and nitrogen. In air, AM demonstrate significantly greater O2 utilization. In nitrogen, (where glycolysis is the major source of energy provision) lactate production is two- to threefold greater in the PM. A comparison of several enzymes of energy metabolism in AM and PM indicate that one basis for the differences in cell energetics is a difference in activity of key enzymes of both the oxidative phosphorlyative and the glycolytic sequences. Exposure of cultivated AM to hypoxic conditions results in changes in the activity of these enzymes such that the AM closely resembles the PM. A key enzyme in oxidative phosphorylation (cytochrome oxidase) shows decreased activity and reaches values similar to those found in the PM. A key enzyme in glycolysis (pyruvate kinase) shows increased activity to values resembling those found in the PM. These alterations in enzyme pattern occur in isolated cell systems, suggesting that molecular O2 modifies the intrinsic cellular regulation of some enzymes of energy metabolism. Alterations in O2 tension may lead to alterations of the rate of biosynthesis and (or) the rate of biodegradation of key enzymes involved in oxidative phosphorylation and glycolysis. In turn, the alteration of enzyme patterns leads to a more suitable bioenergetic pattern as a function of O2 availability.
Assuntos
Líquido Ascítico/citologia , Metabolismo Energético , Macrófagos/metabolismo , Consumo de Oxigênio , Alvéolos Pulmonares/citologia , Animais , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Glicólise , Lactatos/metabolismo , Macrófagos/enzimologia , Camundongos , Fosforilação Oxidativa , Fosfofrutoquinase-1/metabolismo , Piruvato Quinase/metabolismo , CoelhosRESUMO
Chronic hypoxia results in increased measured activity of all of the glycolytic enzymes and is associated with an increase in glycolytic capacity. Phosphofructokinase, a rate-limiting glycolytic enzyme, was measured under normoxic and hypoxic conditions to determine the relationship between increased activity and enzyme content. Monoclonal antibodies were used to isolate pure enzyme in rat skeletal muscle cells (L8) cultured hypoxically (PO2 = 14 torr) and normoxically (PO2 = 142 torr). Phosphofructokinase content per cell in cultures maintained under chronic (96 h) hypoxic conditions was twice that of cells cultured under normoxic conditions (0.0675 +/- 0.008 (S.E.) and 0.0345 +/- 0.003 micrograms enzyme protein/microgram DNA, P less than 0.01). Phosphofructokinase activity increased proportionately (hypoxia, 0.020 +/- 0.003; normoxia, 0.010 +/- 0.001 units/microgram DNA). The specific activity (units/mg enzyme protein) of phosphofructokinase in the hypoxic (296 +/- 32) versus the normoxic (290 +/- 15) cultures was not significantly different, indicating that the increased activity was accounted for by an increase in enzyme content. Glycolytic rate appears to be regulated at the level of enzyme content.
Assuntos
Hipóxia/enzimologia , Músculos/enzimologia , Fosfofrutoquinase-1/metabolismo , Animais , Anticorpos Anti-Idiotípicos/análise , Anticorpos Monoclonais , Células Cultivadas , Ensaio de Imunoadsorção Enzimática , Fosfofrutoquinase-1/imunologia , Radioimunoensaio , RatosRESUMO
Hyperoxic exposure in vitro of two lung-derived cell types (the epithelial-derived L2 cells and WI-38 fibroblasts) inhibits cellular replication, produces striking morphologic changes and may result in cell death; these effects have been observed consistently in other cell types. Hyperoxic exposure of L2 cells is associated with an increase in cellular cyclic AMP content (cellular cyclic AMP content 454 +/- 115 fmol/micrograms DNA in cells exposed to pO2 677 Torr for 96 h compared to 136 +/- 17 fmol/microgram DNA in air-grown cells). Hyperoxic exposure of WI-38 fibroblasts is not associated with increased cyclic AMP content. Although cultivation of L2 cells in the presence of exogenous dibutyryl cyclic AMP does inhibit replication and produce morphologic alterations, similar effects are produced by sodium butyrate alone. Hyperoxic exposure alters cyclic AMP metabolism in some cell types, but the structural and functional alterations observed in L2 cells and WI-38 fibroblasts following hyperoxic exposure are not produced by changes in cellular cyclic AMP content.
Assuntos
AMP Cíclico/metabolismo , Pulmão/fisiologia , Anaerobiose , Animais , Bucladesina/farmacologia , Divisão Celular/efeitos dos fármacos , Linhagem Celular , AMP Cíclico/farmacologia , Epitélio/fisiologia , Fibroblastos/fisiologia , Humanos , Pulmão/efeitos dos fármacos , Pressão , RatosRESUMO
The rate of biosynthesis of pyruvate kinase (ATP:pyruvate 2-O-phosphotransferase, EC 2.7.1.40) was compared in cells maintained under normoxic or hypoxic conditions. L8 cells (a myoblast cell line) were pulse-labeled with [3H]leucine and incorporation of radioactivity into pyruvate kinase was measured after quantitative affinity separation with anti-pyruvate kinase monoclonal antibody. During chronic hypoxia there is an increased rate of biosynthesis of pyruvate kinase leading to an increase in enzyme content and augmented glycolytic capacity. An inhibitor of the electron transport chain, antimycin A, was used to determine whether changes in pyruvate kinase content occurring during hypoxia are a result of reduction in molecular oxygen directly or an indirect consequence of oxygen depletion. Pyruvate kinase activity increased during chronic antimycin A exposure under normoxic conditions. The increase was quantitatively accounted for by an increase in cellular pyruvate kinase enzyme content. This suggested that decreases in the levels of molecular O2 are not the direct stimulus for the increased content of pyruvate kinase. It is more likely that the increased pyruvate kinase content results from depressed rates of electron transport through the mitochondrial electron transport chain.
Assuntos
Hipóxia/enzimologia , Piruvato Quinase/biossíntese , Animais , Antimicina A/farmacologia , Células Cultivadas , Transporte de Elétrons/efeitos dos fármacos , Glicólise , Camundongos , Mitocôndrias/metabolismoRESUMO
The ultimate cause of the clinical abnormalities associated with changes in oxygen supply and oxygen utilization is the development of abnormal tissue oxygen metabolism. Until now, there has been no satisfactory term to describe abnormal tissue oxygen metabolism. We propose the term "dysoxia" to fill this gap. There are a number of causes of dysoxia. One of the most interesting is that form of dysoxia related to abnormal mitochondrial structure and function. In this group of disorders, there is abnormal tissue oxygen metabolism, although oxygen supply is normal. Another interesting cause of dysoxia is exposure to high oxygen concentrations. High oxygen concentrations are involved in producing abnormal tissue oxygen metabolism under a number of different circumstances. The concept underlying dysoxia provides a unified approach to a large and important group of disorders involving most branches of clinical medicine.
Assuntos
Mitocôndrias/metabolismo , Consumo de Oxigênio , Criança , Pré-Escolar , Cianetos/intoxicação , Dinitrofenóis/intoxicação , Edema/metabolismo , Transporte de Elétrons , Humanos , Hipertireoidismo/metabolismo , Hipotireoidismo/metabolismo , Hipóxia/etiologia , Recém-Nascido , Ferro/intoxicação , Síndrome dos Cabelos Torcidos/metabolismo , Músculos/metabolismo , Oxigênio/efeitos adversos , Oxigênio/intoxicação , Síndrome de Reye/metabolismo , Salicilatos/intoxicaçãoRESUMO
Massive cyanide poisoning occurred in a 21-year-old man who had ingested 600 mg of potassium cyanide. The clinical course was marked by acute pulmonary edema and lactic acidosis. Because the poison was unidentified until nine hours after ingestion, the patient received only supported treatment which included diuresis, oxygen, bicarbonate, and assisted ventilation. A review of the literature shows that many case reports are poorly documented and do not provide a firm basis for evaluating therapy. To our knowledge, only four patients, including ours, have had blood levels of cyanide measured. In the absence of a suitable history, diagnosis of cyanide poisoning is difficult. A simple chemical test which can be performed on gastric aspirate is available. Hydroxocobalamin may be used as a nontoxic specific antidote. Nonspecific supportive therapy is of great importance.
Assuntos
Acidose/induzido quimicamente , Cianetos/intoxicação , Edema Pulmonar/induzido quimicamente , Adulto , Antídotos/uso terapêutico , Bicarbonatos/uso terapêutico , Diurese , Humanos , Hidroxocobalamina/uso terapêutico , Lactatos/sangue , Masculino , Oxigenoterapia , Cloreto de Potássio/uso terapêuticoRESUMO
A 76-year-old man had small bowel obstruction and organic small bowel disease following a series of bizarre massive gustatory insults that involved food, medications, and mega-mineral-vitamin supplements. Intestinal obstruction required partial small bowel resection. The dietary indiscretions resulted in severe enteritis (indiscretion enteritis). The sequence has been termed a Rabelaisian syndrome after the great French writer and physician, Francois Rabelais, who vividly described bizarre gustatory habits. Gut injury may result from unwise oral intake of various foods and mineral supplements.
Assuntos
Enterite/etiologia , Comportamento Alimentar , Obstrução Intestinal/etiologia , Idoso , Enterite/cirurgia , França , História do Século XVI , Humanos , Ileíte/etiologia , Obstrução Intestinal/complicações , Obstrução Intestinal/cirurgia , Doenças do Jejuno/etiologia , Literatura Moderna , Masculino , Medicina na LiteraturaRESUMO
Chronic thromboembolic occlusion of the left pulmonary artery in a 36 year old woman is described, and similar cases reported in the past 15 years are discussed. On review, this disease remains a rare entity. In the majority of cases, the etiology is thrombophlebitis and acute pulmonary embolism. Associated cardiopulmonary disease is uncommon. The most common presenting symptom is unexplained dyspnea, and the majority of patients have past histories of hemoptysis. Acute cardiovascular collapse is distinctly rare. Most physical signs and laboratory tests are normal or nonspecific. The perfusion lung scan, although nonspecific, is the best screening test. Antemortem diagnosis, with rare exception, is established by pulmonary angiography. Eleven patients have been operated on: thromboembolectomy in nine, saphenous vein graft in one and pneumonectomy in one. Operative mortality was 36 per cent (four of 11), definite improvement was seen in 46 per cent (five of 11), and 18 per cent (two of 11) survived the operation with no improvement. The role of medical therapy in this disease is considered.