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)

To study the relationship between proximal tubular reabsorption of bicarbonate, sodium, and chloride, the effects of changes in plasma PCO2 were examined in anesthetized dogs. Distal tubular reabsorption was inhibited by ethacrynic acid; plasma bicarbonate concentration was kept constant at 33.4 +/- 0.3 mM; glomerular filtration rate (GFR) was varied over a wide range to examine glomerulotubular balance (constant fractional reabsorption). Hypercapnia (PCO2, 112.0 +/- 2.5 mmHg) increased bicarbonate reabsorption by about 30%, and hypocapnia (PCO2, 19.8 +/- 0.6 mmHg) decreased reabsorption of bicarbonate by more than 50% and altered reabsorption of sodium, chloride, and bicarbonate in the molar ratios 2.7:1.6:1, respectively. During hypercapnia the range of glomerulotubular balance was extended to a GFR 125% of control. During hypocapnia glomerulotubular balance was present only at GFR below 50% of control; reabsorption of bicarbonate sodium, and chloride was constant at GFR exceeding 50% of control. During metabolic acidosis hypercapnia had no significant effect on reabsorption of bicarbonate, sodium, and chloride. These observations support the hypothesis that bicarbonate reabsorption is the main driving force for osmotic reabsorption of water and NaCl in the proximal tubules.
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PMID:Coupling of NaHCO3 and NaCl reabsorption in dog kidneys during changes in plasma PCO2. 42 65

Six patients with chronic obstructive pulmonary disease (COPD) (forced expiratory volume in one second, 1.01 +/- 0.08 L [mean +/- SEM] ) were given either 1 mL of 100% alcohol per kilogram of body weight in an aqueous solution or a similar volume of water in a crossover design on consecutive days. All subjects became intoxicated and the peak alcohol concentration was 137 +/- 11 mg/dL, 40 minutes after ingestion. No significant difference was found in either PaO2 or PaCO2 between the alcohol and control period. A significant decrease in arterial pH occurred following alcohol (P less than .05), and represented a mild metabolic acidosis. Alcohol ingestion resulted in an increase in oxygen consumption (P less than .05) and carbon dioxide production (P less than .05) but no change in respiratory rate. It appears that small to moderate amounts of alcohol will not cause marked changes in oxygen tension or alveolar hypoventilation in patients with severe COPD who do not have marked hypercapnia. Nevertheless, other effects of alcohol on the cardiopulmonary system and the concomitant use of sedatives have to be considered before condoning the use of alcohol.
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PMID:Moderate alcohol dose and chronic obstructive pulmonary disease: not a cause of hypoventilation. 43 97

In chronic obstructive pulmonary disease (COPD), the neuromuscular response to an acute increase in airflow produced by external flow resistive loads (FRL) is impaired. The present study compared the response to FRL of 15 subjects with airway obstruction due to asthma and that of 15 normal subjects. FRL were applied during progressive hypercapnia and isocapnic hypoxia produced by rebreathing techniques to permit the response to be assessed at the same degree of CO2 or O2 drive. The neuromuscular response to FRL was assessed from the airway occlusion pressure developed 100 msec after the onset of inspiration (P100), as well as ventilation. During control rebreathing, ventilatory responses to hypercapnia (ratio of change in minute ventilation to change in PCO2, delta VE/delta PCO2) and hypoxia (ratio of change in VE to the change in percentage of O2 saturation, delta VE/deltaSO2) were the same in asthmatic and normal subjects despite differences in the mechanics of breathing. The P100 response to hypercapnia delta P100/delta PCO2) and hypoxia (delta P100/delta SO2) as well as absolute P100 at any given degree of O2 and CO2 drive was greater during control rebreathing in asthmatics than in normal subjects (P less than 0.05). FRL values of 9 and 18 cm H2O per L per sec applied during either hypercapnia or hypoxia increased the occlusion pressure to a greater extent in asthmatics than in normal subjects. Methacholine-induced bronchoconstriction was used to test the effect of acute airway obstruction on the response to FRL. Bronchoconstriction was associated with an increase in the P100 response to hypercapnia and to FRL, despite increases in lung volume and decreases in inspiratory muscle force. We conclude that: (1) asthmatics with airway dysfunction have an increased nonchemical drive to breathe mediated at least in part by sensory receptors in the airways; (2) asthmatics with airway obstruction respond supernormally to acute changes in resistance to airflow, unlike subjects with COPD. The failure of COPD subjects with prolonged airway obstruction to respond to FRL may be due to adaptation of the sensory mechanisms that respond to changes in airway resistance.
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PMID:The respiratory neuromuscular response to hypoxia, hypercapnia, and obstruction to airflow in asthma. 48 28

To study pulmonary transvascular filtration of fluid and the normal adaptive response of newborn animals to excessive water in the lungs, we measured lung lymph flow, pulmonary vascular pressures, and the concentration of protein in lymph and plasma of nine unanesthetized 1- to 3-wk-old lambs, before, during, and after a rapid iv infusion of isotonic saline, 130-250 ml/kg.hr for 3-4 hr. During infusions, lung vascular pressures increased, the transvascular gradient of protein osmotic pressure decreased, and there was a 2- to 5-fold increase of lung lymph flow. When infusions stopped, lymph flow decreased, as the concentration of protein in plasma increased and pulmonary vascular pressures decreased to new steady-state levels. The concentration of protein in lymph did not change for several hours after the infusions. Body weight increased by 28% and extravascular lung water content was 19% above normal after saline; these changes were associated with mild tachypnea, hypercarbia, and hypoxemia. Sections of lung from these lambs had prominent cuffs of fluid surrounding large blood vessels.
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PMID:Lung fluid balance in awake newborn lambs with pulmonary edema from rapid intravenous infusion of isotonic saline. 50 55

The kinetics of erythropoiesis in 5--6 month old Salmo salar L. was correlated to 4 combinations of environmental PO2 and pH/PCO2. Given single doses of 55Fe at the start of continuous flow bioassays, the incorporation was examined in circulating red blood cells (RBC) by autoradiography on blood smears. The proportions of immature, labelled immature and labelled mature erythrocytes were calculated on samples taken at intervals up to 52 days. Compared to control fish kept at a PO2 corresponding to 90% air saturation and pH/PCO2 at 7.6/8 pH unit/mmHg, oxygen depletion to 50% air saturation stimulated the proliferation of RBC stem cells and enhanced RBC maturation. Ceteris paribus, sustained hypercapnia at a PCO2 in a respiratory water raised to 23 mm Hg (pH 7.1--7.2), stimulated proliferation but did not affect the output of mature RBC. Simultaneously lowered PO2 and raised PCO2 to the levels mentioned above obviously stressed the fish, as the effect of lowered PO2 per se was not manifested. Radioactivity was traced to all electrophoretically separable protein fractions from RBC hemolysates. The relevance of blood physiological criteria for probing the fitness or well being of fish in environmental respiratory stress conditions has been discussed.
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PMID:Autoradiography on erythrokinesis and multihemoglobins in juvenile Salmo salar L. at various respiratory gas regimes. 56 21

The effects of hypoxia and hypercapnia on the electric activity of cerebral vesicles have been studied in 48 unrestrained eels placed in water in a soundproof location. 1. Hypoxia (PwO2 less than 5 torr) was well endured for 8 hours after which sharp bursts appeared, rapidly followed by cerebral death. 2. Hypercapnia (PwCO2 congruent to 14 torr) gave an amplitude decrease in cerebral activity beginning with the first hour, and after 8 hours there was an appearance of slow waves which progressively invaded the recording while the latency of average VER increased. 3. The large resistance of eels to hypoxia, is discussed in relation to the importance of anaerobic glycolysis in fish. The effects of hypercapnia on cerebral electric activity in eels are comparable to those observed in mammals and may be due to metabolic and electrolytic modification in CRL and in nervous cells.
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PMID:[Electrical activity of the brain of the eel (Anguilla anguilla L.) subjected to hypoxia and hypercapnia]. 61 48

The influence of the prevailing PaCO2 on the water-retaining effects of sustained elevations in ADH was assessed by administering vasopressin (5 U in oil, twice daily) and a fixed water intake to dogs with eucapnia (n, 7), chronic hypercapnia (n, 6), and chronic hypocapnia (n, 8). Although water excretion initially fell to a similar extent in all three groups, cumulative water retention by day 4 of vasopressin administration was 77 mg/kg in the hypocapnic group, 46 ml/kg in the eucapnic group, and only 14 ml/kg in the hypercapnic group. These differences were reflected in a marked disparity in the degree of hyposmolality of body fluids, plasma osmolality falling by day 4 to an average value of 223, 237, and 268 mosmol/kg in the hypocapnic, eucapnic, and hypercapnic animals, respectively. In a separate group of dogs, water deprivation and water loading studies revealed that sustained hypercapnia does not affect the maximal concentrating or diluting ability of the kidney. We conclude, therefore, that the striking influence of the prevailing PaCO2 on the water-retaining effects of administered vasopressin cannot be ascribed to an altered responsiveness of the nephron per se, but that this influence reflects an alteration in the ease with which the kidney can escape from the antidiuretic effects of this substance.
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PMID:Influence of steady-state PaCO2 on escape from ADH-induced water retention in the dog. 64 65

In rats, the phenomenon of considerable increase in resistance to acute hypoxia observed after 2-hour stay under conditions of gradually increasing concentration of CO2, decreasing concentration of O2, ANd external cooling at 2--3 degrees seems to be based mainly on changes in concentration of CO2 (ACCORDINGLY, PCO2 and other forms of CO2 in the blood). The high resistance to acute hypoxia develops as well after subcutaneous or i.v. administration of 1.0 ml of water solution (169.2 mg/200 g) NaHCO2, (NH4)2SO4, MgSO4, MnSO4, and ZnSO4 (in proportion: 35 : 5 : 2 : 0.15 : 0.15, resp.) or after 1-hour effect of increased hypercapnia and hypoxia without cooling.
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PMID:[Role of CO2 fixation in increasing the body's resistance to acute hypoxia]. 72 Jun 76

The influence of continuous positive airway pressure (CPAP) and positive end-expiratory pressure (PEEP) on mortality and complication rates in severe hyaline membrane disease (HMD) was evaluated in a randomized, prospective study. Patients were admitted to the study if the Po2 was less than 50 mm Hg with FiO2 greater than 0.6. Twenty-four patients in each of three weight groups were equally divided between treatment and control groups. The treatment regimen included CPAP (6 to 14 cm H2O) for spontaneously breathing patients and PEEP for patients requiring mechanical ventilation for apnea or hypercapnia (Pco2 greater than 65 mm Hg). Control patients received oxygen and were mechanically ventilated if they had apnea, hypercapnia, or Po2 less than 50 mm Hg with FiO2 greater than 0.8. Oxygenation improved after the start of CPAP or PEEP; however, Pco2 rose after CPAP was initiated. There was no significant difference between treatment and control groups in mortality, requirement for mechanical ventilation, or incidence of pulmonary sequelae. The incidence of pulmonary air-leak was increased with Peep. the findings suggest that CPAP and PEEP have not significantly altered the outcome of HMD.
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PMID:Is continuous transpulmonary pressure better than conventional respiratory management of hyaline membrane disease? A controlled study. 79 89

The effect of moderate hypercapnia on right-thoracic duct lymph flow, pulmonary hemodynamics, and lung water content was studied in seven 2- to 5-wk-old dogs and eleven adult dogs anesthetized with pentobarbital, paralyzed with succinylcholine, and maintained on intermittent positive-pressure ventilation. Following a 30-min control period in which arterial pH and blood gases were maintained within normal limits, the dogs were ventilated with 3-14% CO2 for 30 min; they were then returned to control conditions fro a 30-min recovery period. Hypercapnia was associated with a significant increase in lymph flow rate in both pups and adult dogs (P less than 0.05) and a significant increase in pulmonary artery and pulmonary artery wedge pressures in adult dogs (P less than 0.05). These data suggest that hypercapnia may increase the net flow of water out of the pulmonary vascular bed.
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PMID:Hypercapnia and right-duct lymph flow in pups and adult dogs. 84 77


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