Blood Carbonic Anhydrase Activity Research Articles

Relationship between zinc content and carbonic anhydrase activity in blood of anemic pregnant women in Turkey.

Carbonic anhydrase (CA) in pregnancy plays an important part in gaseous exchange across the placenta. The aim of our study was to determine the relationship between zinc content and the CA activity in blood of anemic and normal pregnant women in their third trimester, in Turkey. The patients with hemoglobin values below 11 g/dL were accepted as anemic. CA enzyme activity and zinc levels in erythrocyte of anemic and non-anemic pregnant women were carried out in 27 non-anemic pregnant women and 31 anemic pregnant women. Mean corpuscular volume (MCV) levels of the participants were also tested. Zinc levels were lower in the anemic group compared to the non-anemic group (P = 0.049). Total CA enzyme activity was also lower in the anemic group (P = 0.044). MCV levels were found to be lower in the anemic group (P = 0.007). The decrease in these values was statistically significant (P < 0.05). This is the first study to evaluate the zinc content in red blood cells of anemic pregnant women in the third trimester and its relationship with carbonic anhydrase activity. CA isoenzymes to work healthily, providing iron and zinc supports is important for fetal development.

Carbonic anhydrase, obstructive sleep apnea and hypertension: Effects of intervention.

Whole blood carbonic anhydrase activity (CAa) is increased in patients with obstructive sleep apnea (OSA). Our study investigated the influence of positive airway pressure (PAP) or CA inhibitor acetazolamide (ACT) therapy on CAa, OSA and blood pressure. Thirty-three OSA patients (21 hypertensive, body mass index (BMI) 37±7kg/m2 and apnea-hypopnea index (AHI) of 47±31 events/hr) were followed-up after PAP treatment (compliance, 4.7±1.5hr/day; duration, median 6 [IQR 6,6] months) (Cohort A). A second OSA Cohort (B) contained nine hypertensive patients (BMI, 29±4kg/m2 ; AHI, 39±20 events/hr) with 2-week treatment of ACT, PAP or ACT+PAP in an open crossover study. CAa was assessed at baseline and at the end of each treatment period. In Cohort A, baseline CAa was higher in hypertensive, compared with normotensive, patients (1,033±204 versus 861±201 units, p=.028). PAP treatment reduced systolic/diastolic blood pressure but not CAa (-9±11/-5±7mmHg and -20±289 units, p<.001, <.001 and .70). In Cohort B, blood pressure was reduced in both ACT-treated groups (-10±10/-5±7mmHg, p=.043 and .019; and -5±5/-13±13mmHg, p<.001 and .009). AHI was reduced in both groups: ACT only, -17±9 events/hr p=.001; and ACT+PAP, -39±19 events/hr, p<.001. PAP did not change CAa (p=.98) but activity tended to decrease after ACT with or without PAP (p=.081 and .056). CAa is elevated in hypertensive OSA patients. Long-term PAP reduced blood pressure without affecting CAa. ACT reduced blood pressure and CAa. Increased CAa may constitute a physiological characteristic in OSA, contributing to comorbid hypertension.

Comparison of blood carbonic anhydrase activity of athletes performing interval and continuous running exercise at high altitude

The effects of high-intensity interval and continuous exercise on erythrocytes carbonic anhydrase (CA, EC 4.2.1.1) activity levels were scarcely investigated up until now. Here we present a study focused on the CA activity from erythrocytes of athletes experiencing interval and continuous training for 6 weeks, during cold weather and at high altitude (> 1600 m). We observed a 50% increase in the blood CA activity at the second week after initiation of the training in both interval and continuos running groups, whereas the control group did not experience any variation in the enzyme activity levels. In the trained individuals a mild decrease in their body mass, BMI and an increased were also observed. The CA activity returned at the basal values after 4–6 weeks after the training started, probably proving that a metabolic compensation occurred without the need of an enhanced enzyme activity. The unexpected 50% rise of activity for an enzyme which acts as a very efficient catalyst for CO2 hydration/bicarbonate dehydration, such as the blood CA, deserves further investigations for better understanding the physiologic basis of this phenomenon.

The effects of elevated carbon dioxide and temperature levels on tilapia (Oreochromis mossambicus): Respiratory enzymes, blood pH and hematological parameters.

Oreochromis mossambicus were exposed to two different temperature and carbon dioxide partial pressure levels for about two weeks, as the ambient (Control; 25°C, 3.3mg/L CO2), high CO2 (25°C, 14mg/L CO2), high temperature (30°C, 3mg/L CO2) and combined (30°C, 14.1mg/L CO2) groups. No mortality was observed during the experiments. As a result of the study, elevated CO2 concentrations cause negative effects on the hematological parameters. At the end of the study, while the blood Carbonic Anhydrase (CA) activity, in the high CO2 group (25°C, 14mg/L CO2), statistically increased at the 7th day compared to the control group, it decreased at the 14th day (p<0.05). In addition, the blood CA activity, in the combined (30°C, 14.1mg/L CO2) group, showed a decrease at the 14th day compared to the control group (p<0.05). At the end of study, unlike the blood CA activity, gill, liver and kidney CA activity showed an increase in the tissues compared to the control groups (p<0.05). Furthermore, the Na(+), K(+)-ATPase activities were stimulated significantly in the gills in both high CO2 and temperature groups at day 7, but it showed a significant amount of inhibition at the 14th day compared to the control groups. Overall, increasing carbon dioxide concentration in different temperatures has negative effects on the hematological parameters and respiratory enzyme of the tilapia fish. In addition, it is observed that the fish survive at negative conditions with adaptation mechanisms.

Increased Carbonic Anhydrase Activity is Associated with Sleep Apnea Severity and Related Hypoxemia.

The catalytic function of the enzyme carbonic anhydrase (CA) plays a fundamental role in carbon dioxide (CO2), proton (H(+)), and bicarbonate (HCO3(-)) homeostasis. Hypoxia and tissue acidosis have been proposed to increase physiological CA activity in various compartments of the body. We hypothesized that CA activity in blood is upregulated in patients with obstructive sleep apnea (OSA). Cross-sectional analysis of a sleep clinic cohort. Sleep laboratory at a university hospital. Seventy referred patients with suspected OSA (48 males, age 54 ± 13 y, apnea-hypopnea index (AHI) median [interquartile range] 21 [8-41] n/h). N/A. In-laboratory cardiorespiratory polygraphy was used to assess OSA. CA activity was determined by an in vitro assay that quantifies the pH change reflecting the conversion of CO2 and H2O to HCO3(-) and H(+). CA activity was positively associated with AHI and 4% oxygen desaturation index (ODI4) (Spearman correlation r = 0.44 and 0.47, both P < 0.001). The associations (CA activity versus logAHI and CA versus logODI4) were independent of sex, age, body mass index, presleep oxygen saturation, nocturnal oxygen saturation, hypertension status, and use of diuretic medication in two generalized linear models (P = 0.007 and 0.011, respectively). Sitting diastolic blood pressure was associated with CA activity after adjustment of sex, age, body mass index, mean oxygen saturation, and AHI (P = 0.046). Carbonic anhydrase (CA) activity increased with apnea-hypopnea index and related nocturnal hypoxemia measures in patients with obstructive sleep apnea (OSA). Altered CA activity may constitute a component that modulates respiratory control and hemodynamic regulation in patients with OSA.

Subcellular distribution and characterization of gill carbonic anhydrase and evidence for a plasma carbonic anhydrase inhibitor in Antarctic fish.

This main purpose of this study was to examine the subcellular distribution and isozyme characteristics of branchial carbonic anhydrase (CA) in Chaenocephalus aceratus, an Antarctic icefish that lacks erythrocytes. The Antarctic fish, Notothenia coriiceps, which possesses erythrocytes, was also studied for comparative purposes. The gills of both species were found to have measurable activity of CA. N. coriiceps also had normal levels of blood CA activity. In contrast, the icefish, C. aceratus, lacked blood CA activity, but was found to possess an endogenous plasma CA inhibitor. The large majority of branchial CA in the gills of these species was located in the cytoplasmic fraction whereas less than 3% was associated with the membrane fraction. In both species, CA from the cytoplasmic gill fraction and membrane fraction differed markedly in terms of their sensitivity to the plasma CA inhibitor from C. aceratus. In addition, treatment with the cleaving enzyme phosphatidylinositol-specific phospholipase C indicated that CA from the branchial membrane fraction of both species is anchored to the membrane via a phosphatidylinositol-glycan linkage. Taken together, these results provide evidence for a CA IV-like isozyme in the gills of Antarctic fish. At present, the functional significance of this membrane-bound CA is unknown, but the relative amount of this isozyme appeared to be greater in the gills of C aceratus, the species that lacked erythrocytes.

Carbonic anhydrase and red blood cell anion exchange in the neotenic aquatic salamander, Necturus maculosus.

Carbonic anhydrase (CA) activity in blood and other tissues and red blood cell (rbc) anion exchange were measured in the mud puppy, Necturus maculosus, in order to gain insight into the strategy for CO2 transport used by these neotenic salamanders and to further explore evolutionary relationships between rbc CA activity and anion exchange in nonmammalian vertebrates. CA activity was detectable in all of the tissues examined, but CA activity in blood was much lower than that in most vertebrates. There was no indication, however, that additional CA had been incorporated into the membrane fraction of other tissues to compensate for this low blood CA activity. In further contrast to most other animals, low levels of CA activity were also detectable in mud puppy plasma. Preliminary characterization of the rbc CA indicated that the Type II, fast-turnover enzyme was indeed present, but that there are a very low number of active sites in mud puppy rbc's. Further experiments showed that the rbc's were highly permeable to anions and that the relative rate of anion flux could be inhibited by 4, 4-diisothiocyanostilbene-2,2-disulphonic acid. Thus, the process of CO2 transport in the blood of mud puppies probably involves components of the Jacobs-Stewart cycle, as in most other vertebrates.

Carbonic anhydrase activity in blood of early sheep fetuses

1. 1. The level of carbonic anhydrase activity in the red cells was measured in sheep fetuses at different times after conception: 39, 56, 77, 90 and 140 days, the last being close to full term. Measurements were also made on blood from four of the mothers. 2. 2. There was a low level of the enzyme present in the 39 day fetuses (0.037 enzyme units (E.U.)/100 μg Hb) and its increase up to 90 days of gestation (0.19 E.U./100 μg Hb) had a form approximating exponential. 3. 3. The earliest levels were only 11% of the full term levels and only 4% of the adult levels previously reported. 4. 4. Even the earliest samples were of blood that was fetal rather than embryonic but these results are the earliest carbonic anhydrase activities reported in this mammal.

Changes in carbonic anhydrase activity in coho salmon smolts resulting from physical training and transfer into seawater

1. 1. Carbonic anhydrase (CA) activity was measured in blood and in gill tissue of coho salmon smolts during chronic exercise and subsequent transfer into seawater. 2. 2. The mean level of CA activity was higher in blood than gill tissue in both freshwater and seawater. 3. 3. CA activity in gill tissue increased significantly after the smolts had adapted to seawater. 4. 4. CA activity in blood decreased significantly in the group of fish given the highest exercise level after they had adapted to seawater. 5. 5. There were no significant differences in CA activity in gill tissue between control and exercise groups in either freshwater or seawater.

An investigation of the carbonic anhydrase inhibitor in eel plasma

1. 1. Carbonic anhydrase activity in blood and gill from freshwater and seawater acclimated European eels, Anguilla anguilla has been determined. 2. 2. Plasma from freshwater and seawater eels possess a potent inhibitor of erythrocytic carbonic anhydrase, in agreement with previous investigations on freshwater fish. 3. 3. The plasma inhibitor is equally effective against gill and gut carbonic anhydrase from the eel. Although not as potent, the eel inhibitor is also effective against CA from rainbow trout. The inhibitor was without effect on bovine-CA. 4. 4. The inhibitor is heat-PCA- and trypsin-labile. It is also non-dialyzable and insensitive to concanavalin A. Using gel filtration, the inhibitor appears to be a fairly small molecular weight protein approximately 10,000–30,000.

Comparison of carbonic anhydrase activity and other haematological values of two eutherian and three Australian marsupial mammals

1. 1. Carbonic anhydrase activity and 2,3-diphosphoglycerate (2,3-DPG) concentration were determined in whole blood from humans ( Homo sapiens), rabbits ( Oryctolagus cuniculus), eastern grey kangaroos ( Macropus giganteus), pademelons ( Thylogale billardierii) and brush-tailed possums ( Trichosurus vulpecula). 2. 2. Marsupial blood carbonic anhydrase activity increased as species body size decreased. 3. 3. T. billardierii haemoglobin was found to have a polymorphism which may be the same (β2 = histidine or glutamine) as that of M. giganteus. 4. 4. The concentration of 2,3-DPG in the red cells of T. billardierii was approximately equal to that of the haemoglobin tetramer. Levels of 2,3-DPG in the other species were similar to those previously reported.

Carbonic anhydrase (acetazolamide-sensitive esterase) activity in the blood, gill and kidney of the thermally acclimated rainbow trout, Salmo gairdneri.

1. Gill, kidney and blood levels of acetazolamide-sensitive esterase (carbonic anhydrase) activity were estimated at acclimation temperature and at a common temperature (25 degrees C) in rainbow trout acclimated to 2, 10 and 18 degrees C. Plasma levels of sodium, potassium and chloride were also examined for possible acclimatory variations. 2. Plasma sodium and chloride levels, and the sodium:chloride ratio were unaffected by thermal acclimation; potassium concentrations were significantly elevated at 18 degrees C. 3. Significant, but modest changes in renal and branchial carbonic anhydrase activity were observed under physiologically realistic incubation temperature conditions. Blood carbonic anhydrase activity was sharply elevated at higher acclimation temperatures. 4. The data are discussed in relation to the hypothesis that carbonic anhydrase in this relatively stenothermal freshwater salmonid, through its intimate association with the coupled HCO-3/CL- and H+ +NH+4/Na+ exchange systems may provide for relatively thermostable basal rates of sodium and chloride uptake from the medium and recovery from urine. The renal, and more notably the branchial (Na+/K+)-stimulated ATPase systems, and erythrocytic carbonic anhydrase may then serve primarily as high-temperature amplifiers of sodium and chloride recruitment respectively.

Carbonic anhydrase in flounder erythrocytes

1. 1. The blood carbonic anhydrase activity of the starry flounder was found to be approximately 40 enzyme units per milliliter of blood. These findings are in contrast with previously published reports on the absence of carbonic anhydrase activity in flounder blood. 2. 2. Carbonic anhydrase in the blood of Rainbow trout is not found exclusively in the cytosol, as in mammalian erythrocytes. It is suggested that the major portion of erythrocytic carbonic anhydrase is associated with the plasma membrane. 3. 3. The applicability of previous assay methods are discussed.

MECHANISM OF ACTION OF ALDOSTERONE IN ADRENALECTOMIZED

Effects of cycloheximide and aldosterone, alone or in combination, on kidney, liver and blood carbonic anhydrase activity, kidney Na+-K+-ATPase activity and on urinary excretion of sodium were investigated using normal and adrenalectomized mice to clarify the significance of above enzymes as a mediator of action of aldosterone on sodium excretion.1. In normal mice, cycloheximide decreased kidney and blood carbonic anhydrase activity. The inhibition rates are parallel with the increase of doses and the maximum effect was observed at 4 hr after treatment. Liver carbonic anhydrase and kidney ATPase activities were not affected by cycloheximide.2. In adrenalectomized mice, combined administration of cycloheximide inhibited the aldosterone-induced increase of kidney carbonic anhydrase activity and decrease of urinary excretion of 22Na. Kidney ATPase activity was unaltered in above condition.3. In adrenalectomized mice, single injection of cycloheximide did not affect the enzyme activity and sodium excretion.

Blood carbonic anhydrase activity in the newborn.

Erythrocyte carbonic anhydrase activity was measured in 7 adults, 12 mature newborn infants, 12 preterm low birthweight infants, 9 `dysmature9 infants, 33 infants with the respiratory distress syndrome (RDS), and 5 infants who had received intrauterine transfusions. The mean level of enzyme activity in infants with RDS was 3·6% of normal adult level, 21% of the mean level in mature infants, and 30% of the mean level in dysmature infants. There was, however, no significant difference between the mean enzyme activity found in infants with RDS and in low birthweight, preterm infants without RDS. In 3 of the 5 infants treated by intrauterine transfusion RDS developed while the carbonic anhydrase activity was up to adult levels. It is unlikely that the very low enzyme levels found in premature infants have any aetiological relation to the development of RDS, and there is no indication for treatment by exchange transfusion.

Carbonic anhydrase isoenzymes in infants with respiratory distress syndrome.

Blood obtained from umbilical cords of 106 preterm infants was analyzed for carbonic anhydrase (CA) activity. Carbonic anhydrase isoenzymes were measured in red blood cells from five adults, eight full-term newborn infants, and 16 premature infants. Carbonic anhydrase activity increased progressively with gestation. Infants with respiratory distress syndrome (RDS) had lower cord blood CA activity than infants without RDS. Carbonic anhydrase B (CA-B), carbonic anhydrase C (CA-C), and total carbonic anhydrase protein (CA-B + CA-C) were highest in adults, then full-term newborns, premature newborns without RDS, and infants with RDS. The ratio of CA-B/CA-C was the same for all newborn groups and lower than the adult ratio. All enzyme activity in newborns could be accounted for by CA-B and CA-C. No inhibitors or abnormal enzymes were present. Importance of findings to RDS pathogenesis is discussed.

Carbonic anhydrase isonenzymes in infants with respiratory distress syndrome

Carbonic anhydrase (CA), a zinc metalloenzyme existing in several isoenzymic forms, is involved in CO2 transport at the cellular and pulmonary levels. Previously we reported (N. Engl. J. Med. 277:1t57, 1967) that infants with respiratory distress syndrome (RDS) had lower cord blood CA activity than infants without RDS. The present study includes a larger number of premature infants (104) to distinguish between the low CA due to immaturity or to RDS. Cord red blood cell CA activity increased with gestational age but at all stages of maturity infants with RDS had lower CA activity than similar infants without RDS (p ~ 0.05 for all gestational age groups). CA isoenzymes B and C (CA-B and CA-C) increased with maturation but were lower in infants with than without RDS (p ~ 0.05). Specific activities (enzyme activity/enzyme protein) of CA-B and CA-C were the same for infants with RDS, normal infants, and adults indicating that the low CA activity in infants with RDS is not due to CA inhibitors or abnormal types of CA but to diminished enzyme protein. Total red blood cell zinc was the same for all newborn infants but the ratio, red blood cell zinc/CA protein, was higher for infants with RDS (p ~ 0.05) than any others. This could be due to either: (a) inability to incorporate zinc into CA molecule, (b) an abnormal zinc metalloprotein, or (c) a defect in CA protein synthesis after zinc incorporation into CA precursor. COValENT. Carbonic anhydrase activity was measured using the carbon dioxide hydration reaction; isoenzymes of carbonic anhydrase were identified by immunochemical techniques. Carbonic anhydrase activity is not inhibited by elevated Pco~ or by acidosis. The relationship between carbonic anhydrase activity and the age of the red cell is unknown. As a group, newborn infants with R D S who died had lower carbonic anhydrase activity than infants who survived. However, deaths were more frequent in infants of shorter gestational age, who were the infants who also had lower carbonic anhydrase activity. Within given gestational age periods the number of infants who died was too small to permit statistical comparison. In older children with elevation of Pco2, decreased carbonic anhydrase activity has not been demonstrated.

CARBONIC ANHYDRASE IN THE PREMATURE

Carbonic anhydrase activity was measured in the blood of premature and full-term infants to determine if the arterial-alveolar carbon dioxide gradient was related to low levels of carbonic anhydrase. The time at which levels in these infants approached the adult was studied as well. The study demonstrates that CO2 gradients do not correlate with blood carbonic anhydrase activity, and minimal or no activity can be associated with a small gradient. An increase in the carbonic anhydrase activity-produced by transfusion did not significantly change the CO2 gradient. Premature infants approach adult levels of activity in 6 to 7 months.

Blood carbonic anhydrase activity and zinc concentration in infants with respiratory-distress syndrome.

CARBONIC anhydrase is a zinc metalloenzyme that reversibly catalyzes the hydration of carbon dioxide to bicarbonate and hydrogen ions according to the following equation1: The enzyme is found in red blood cells, kidney, gastric mucosa and, to a lesser extent, the central nervous system, lungs, pancreas and salivary glands.2 Roughton3 and, more recently, Enns4 have discussed the importance of this enzyme for the physiologic transport of carbon dioxide. Earlier investigators found less carbonic anhydrase activity in the blood obtained from newborn infants than from adults, and an even lower enzyme activity in blood obtained from premature infants5 6 7 8 and fetuses. . . .

BLOOD CARBONIC ANHYDRASE ACTIVITY-A POSSIBLE ROLE IN THE PRODUCTION OF ACID-BASE IMBALANCE IN CHILDREN AND INFANTS.

1. Blood carbonic anhydrase activity was estimated in individuals belonging to four age groups. Our results show that the level of activity in adults is significantly higher than in the newborn. 2. A theory was proposed as to the clinical significance of very low carbonic anhydrase levels in premature babies, the newborn, and very young infants.