Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The oxygen affinity of hemoglobin and the factors determining the position of the oxygen dissociation curve were investigated in twenty-five patients with severe chronic obstructive lung disease. Patients have been separated into three groups: group I showed a normal or mild decrease of PaO2, group II a moderate fall in arterial oxygen pressure, and group III a severe hypoxia with balanced acid-base equilibrium and hypercapnia. Blood hemoglobin exhibited a significant increase in all groups, indicating an improved oxygen transport. In most patients a leftward shifting of the oxygen dissociation curve occurred. It is discussed that the tendency to left shifting is based upon alkalosis inside the red cells, evidently demonstrated in all groups studied. 2,3-diphosphoglycerate showed no close relation to evaluated oxygen affinity of hemoglobin. The evidence for an increased oxygen affinity may reveal a further compensatory mechanism in oxygen transport in patients with pulmonary disorders. Additionally the alkalosis inside the cells may counterbalance too great a right shifting of oxygen dissociation curve in vivo when severe hypoxia and hypercapnia occur.
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PMID:Oxygen affinity of haemoglobin and red cell acid-base status in patients with severe chronic obstructive lung disease. 1 84

Ten mongrel dogs (mean weight: 27 kg) awake and with an implanted femoral catheter have been maintained for three days in a controlled chamber (10% CO2 and 21% O2). Arterial blood samples, taken before admission and after one, two, four, six, 24, 48 and 72 hours of exposure, allowed to study blood gases and acid-base equilibrium. Glycemia, phosphatemia, erythrocyte concentration of glucose-6-phosphate (G-6-P), fructose-6-phosphate (F-6-P), fructose-1,6-diphosphate (F-1,6-DP), 2,3-diphosphoglycerate (2,3-DPG), pyruvate, lactate and ATP were also titrated by various enzymatic methods. In addition, nine reference subjects were studied in air (without CO2). During the hypercapnia, [H+] rapidly increases to 70 nmol/1, then progressively decreases after 24 hours, while [HCO3-] slowly rises. The glycemia stays high during the whole exposure. There is also an increase in inorganic phosphate, G-6-P and F-6-P, but during the first 24 hours only. F-1,6-DP, pyruvate and lactate remain lowered during the whole exposure. The 2,3-DPG diminishes after the sixth hour. These phenomena, related to the acidosis and probably to the phosphofructokinase inhibition don't arise in the reference subjects. However the latter present after a two and four hour-stay in the chamber a small decrease in pyruvicemia and lactacidemia.
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PMID:[Intermediates of erythrocyte glycolysis during three days hypercapnia in the dog (author's transl)]. 101 72

Hilltop (H) and Madison (M) strains of Sprague-Dawley rats exhibit strikingly different susceptibilities to the effects of chronic altitude exposure. The H rats develop greater polycythemia, hypoxemia, and pulmonary hypertension. We studied ventilation, pulmonary gas exchange, tissue oxygenation, and hematologic adaptations in the two rat strains during a 50-day exposure to a simulated altitude (HA) of 5,500 m (18,000 ft). There were no strain differences among the variables we studied under sea level (SL) conditions. Within the first 14 days of hypoxic exposure, the only significant strain differences were that erythropoietin (EPO) rose much higher and erythroid activity was greater in the H rats, even though arterial Po2 and PCo2 (Pao2 and PaCo2, respectively), renal venous PO2 (Prvo2), and ventilation (VE) were equivalent in the two strains during this time. By day 14 at HA, the H rats had significantly higher erythroid activity, hematocrit (Hct), and EPO levels, significantly lower PaO2 and PrvO2, but equivalent VE and PaCO2. These changes persisted for the remainder of the exposure, except that the Hct continued to rise and the increase was greater in H rats. Despite the greater O2-carrying capacity of H rats in the later stages of hypoxic exposure, PaO2 and PrvO2 were significantly lower in H rats. There were no strain differences at either SL or HA in ventilatory responses to hypercapnia or hypoxia, in blood O2 affinity or 2,3-diphosphoglycerate, in extrarenal production of EPO, or in EPO clearance. We conclude that early in the hypoxic exposure the H rats produce more EPO at apparently equivalent levels of hypoxia, and this is the first step in the pathogenesis of the maladaptation to HA manifest by H rats. We find no consistent evidence that differences in VE contribute to the variable susceptibility to hypoxia in the two rat strains.
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PMID:Ventilatory and hematopoietic responses to chronic hypoxia in two rat strains. 162 91

In order to study the effect of the decrease in P-Pi caused by low pH on hemoglobin-oxygen affinity, we measured P-Pi,2,3-diphosphoglycerate (2,3-DPG), and oxygen tension at 50% saturation (P50) in 36 cases with acute exacerbation of chronic respiratory failure with hypercapnia. The cases were classified into two groups by arterial blood pH values obtained on the day of admission. Group A: pH less than or equal to 7.35 and Group B: pH greater than or equal to 7.36. P50 was calculated by a modification of Severinghaus' equation developed by Yusa and Kohsaka, and it was corrected by applying the carboxy-hemoglobin (COHb) coefficient. On the day of admission (stage I), 2,3-DPG and P50 in both groups were slightly higher than in the control group. In Group A, a week after admission (stage II), these values decreased and became significantly lower than they had been at stage I. Especially 2,3-DPG in stage II was even lower than those of the control group. Approximately 14 days after admission, in stage III, it was found that these values had risen to the initial level at stage I. In Group A, similar changes were also observed for P-Pi. The value of P-Pi was low in stage II and recovered to the initial value in stage III. On the other hand, we found that the urinary excretion of phosphorus (U-Pi) increased at stage I in Group A. It was supposed that the increase in U-Pi at stage I caused a decrease in P-Pi, which caused the decrease in 2,3-DPG, in stage II.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Hemoglobin-oxygen affinity in acute exacerbation of chronic respiratory failure]. 207

The hemoglobin-oxygen dissociation curve and the relationships between the parameters of tension, saturation, capacity, affinity and concentration of oxygen in the course of respiratory failure in chronic obstructive lung diseases (COLD) were studied. The study included 141 patients divided into four basic groups according to the value of pO2 (a): patients with normoxia, mild, moderate and severe arterial hypoxia. The blood-gas status was determined using the ABL-330 and OSM-3 analyzers (Radiometer A/S, Denmark). It is concluded that: 1. Presence of normoxia (pO2 and sO2 in norm) in COLD patients does not exclude abnormalities in their arterial blood oxygen transport and increased risk of tissue hypoxia. 2. Total oxygen concentration in respiratory failure is relatively stable and "independent" from the stepwise decrease of the arterial pO2, which results from the compensatory increase of the total and effective hemoglobin. 3. There are phase fluctuations of the ctO2/pO2 dissociation curve in the reference interval, expressed in the "lowering" of P50 and p90 in mild hypoxia and the "centering" or "raising" of their values in severe hypoxia. Such fluctuations are more pronounced in the p90 than in the p50. 4. The oxygen extraction tension lowers progressively (without reaching the anaerobic threshold) and the oxygen compensation factor elevates with the pO2 (a) reduction and the arising of hypercapnia and acidemia. 5. The calculated 2,3-diphosphoglycerate (2,3-DPG) concentration values are significantly higher in hypercapnics with COHb > 1% than in those with COHb < 1%. The relationships between hypoxia, oxygen affinity, hemoglobinemia and oxygen affinity as well as the dissociation curve properties in chronic respiratory failure are discussed.
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PMID:Relationships between blood oxygen parameters in patients with chronic obstructive lung disease. 819 1

Blood oxygen transport and tissue oxygenation were studied in 28 calves from the Belgian White and Blue breed (20 healthy and 8 hypoxaemic ones). Hypoxaemic calves were selected according to their high respiratory frequency and to their low partial oxygen pressure (PaO2) in the arterial blood. Venous and arterial blood samples were collected, and 2,3-diphosphoglycerate, adenosine triphosphate, chloride, inorganic phosphate and hemoglobin concentrations, and pH, PCO, and PO2 were determined. An oxygen equilibrium curve (OEC) was measured in standard conditions, for each animal. The arterial and venous OEC were calculated, taking body temperature, pH and PCO2 values in arterial and venous blood into account. The oxygen exchange fraction (OEF%), corresponding to the degree of blood desaturation between the arterial and the venous compartments, and the amount of oxygen released at the tissue level by 100 mL of blood (OEF Vol%) were calculated from the arterial and venous OEC combined with the PO2 and hemoglobin concentration. In hypoxaemic calves investigated in this study, the hemoglobin oxygen affinity, measured under standard conditions, was not modified. On the contrary, in vivo acidosis and hypercapnia induced a decrease in the hemoglobin oxygen affinity in arterial blood, which combined to the decrease in PaO2 led to a reduced hemoglobin saturation degree in the arterial compartment. However, this did not impair the oxygen exchange fraction (OEF%), since the hemoglobin saturation degree in venous blood was also diminished.
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PMID:Blood oxygen binding in hypoxaemic calves. 1205 79

Semi-fossorial ground squirrels face challenges to respiratory gas transport associated with the chronic hypoxia and hypercapnia of underground burrows, and such challenges are compounded in species that are native to high altitude. During hibernation, such species must also contend with vicissitudes of blood gas concentrations and plasma pH caused by episodic breathing. Here, we report an analysis of hemoglobin (Hb) function in six species of marmotine ground squirrels with different altitudinal distributions. Regardless of their native altitude, all species have high Hb-O2 affinities, mainly due to suppressed sensitivities to allosteric effectors [2,3-diphosphoglycerate (DPG) and chloride ions]. This suppressed anion sensitivity is surprising given that all canonical anion-binding sites are conserved. Two sciurid species, the golden-mantled and thirteen-lined ground squirrel, have Hb-O2 affinities that are characterized by high pH sensitivity and low thermal sensitivity relative to the Hbs of humans and other mammals. The pronounced Bohr effect is surprising in light of highly unusual amino acid substitutions at the C-termini that are known to abolish the Bohr effect in human HbA. Taken together, the high O2 affinity of sciurid Hbs suggests an enhanced capacity for pulmonary O2 loading under hypoxic and hypercapnic conditions, while the large Bohr effect should help to ensure efficient O2 unloading in tissue capillaries. In spite of the relatively low thermal sensitivities of the sciurid Hbs, our results indicate that the effect of hypothermia on Hb oxygenation is the main factor contributing to the increased blood-O2 affinity in hibernating ground squirrels.
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PMID:Hemoglobin function and allosteric regulation in semi-fossorial rodents (family Sciuridae) with different altitudinal ranges. 2417 89

Inhabiting deep and sealed subterranean burrows, mole rats exhibit a remarkable suite of specializations, including eusociality (living in colonies with single breeding queens), extraordinary longevity, cancer immunity and poikilothermy, and extreme tolerance of hypoxia and hypercapnia. With little information available on adjustments in haemoglobin (Hb) function that may mitigate the impact of exogenous and endogenous constraints on the uptake and internal transport of O2, we measured haematological characteristics, as well as Hb-O2 binding affinity and sensitivity to pH (Bohr effect), CO2, temperature and 2,3-diphosphoglycerate (DPG, the major allosteric modulator of Hb-O2 affinity in red blood cells) in four social and two solitary species of African mole rats (family Bathyergidae) originating from different biomes and soil types across Central and Southern Africa. We found no consistent patterns in haematocrit (Hct) and blood and red cell DPG and Hb concentrations or in intrinsic Hb-O2 affinity and its sensitivity to pH and DPG that correlate with burrowing, sociality and soil type. However, the results reveal low specific (pH independent) effects of CO2 on Hb-O2 affinity compared with humans that predictably safeguard pulmonary loading under hypoxic and hypercapnic burrow conditions. The O2 binding characteristics are discussed in relation to available information on the primary structure of Hbs from adult and developmental stages of mammals subjected to hypoxia and hypercapnia and the molecular mechanisms underlying functional variation in rodent Hbs.
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PMID:O2 binding and CO2 sensitivity in haemoglobins of subterranean African mole rats. 2885 19