Stopped-flow studies of carbon dioxide hydration and bicarbonate dehydration in water and water-d2. Acid-base and metal ion catalysis

1977 ◽  
Vol 99 (20) ◽  
pp. 6537-6543 ◽  
Author(s):  
Y. Pocker ◽  
D. W. Bjorkquist
Keyword(s):  
Carbon Dioxide ◽  
Metal Ion ◽  
Stopped Flow ◽  
Acid Base ◽  
Metal Ion Catalysis

Does gill boundary layer carbonic anhydrase contribute to carbon dioxide excretion: a comparison between dogfish (Squalus acanthias) and rainbow trout (Oncorhynchus mykiss)

1999 ◽  
Vol 202 (6) ◽  
pp. 749-756 ◽  
Author(s):  
S.F. Perry ◽  
K.M. Gilmour ◽  
N.J. Bernier ◽  
C.M. Wood
Keyword(s):  
Carbon Dioxide ◽  
Boundary Layer ◽  
Rainbow Trout ◽  
Carbonic Anhydrase ◽  
Carbonic Anhydrase Activity ◽  
Squalus Acanthias ◽  
Stopped Flow ◽  
Acid Base ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Co2 Excretion

In vivo experiments were conducted on spiny dogfish (Squalus acanthias) and rainbow trout (Oncorhynchus mykiss) in sea water to determine the potential role of externally oriented or gill boundary layer carbonic anhydrase in carbon dioxide excretion. This was accomplished by assessing pH changes in expired water using a stopped-flow apparatus. In dogfish, expired water was in acid-base disequilibrium as indicated by a pronounced acidification (delta pH=−0.11+/−0.01; N=22; mean +/− s.e.m.) during the period of stopped flow; inspired water, however, was in acid-base equilibrium (delta pH=−0.002+/−0.01; N=22). The acid-base disequilibrium in expired water was abolished (delta pH=−0.005+/−0.01; N=6) by the addition of bovine carbonic anhydrase (5 mg l-1) to the external medium. Addition of the carbonic anhydrase inhibitor acetazolamide (1 mmol l-1) to the water significantly reduced the magnitude of the pH disequilibrium (from −0.133+/−0.03 to −0.063+/−0.02; N=4). However, after correcting for the increased buffering capacity of the water caused by acetazolamide, the acid-base disequilibrium during stopped flow was unaffected by this treatment (control delta [H+]=99.8+/−22.8 micromol l-1; acetazolamide delta [H+]=81.3+/−21.5 micromol l-1). In rainbow trout, expired water displayed an acid-base disequilibrium (delta pH=0.09+/−0.01; N=6) that also was abolished by the application of external carbonic anhydrase (delta pH=0.02+/−0.01).The origin of the expired water acid-base disequilibrium was investigated further in dogfish. Intravascular injection of acetazolamide (40 mg kg-1) to inhibit internal carbonic anhydrase activity non-specifically and thus CO2 excretion significantly diminished the extent of the expired water disequilibrium pH after 30 min (from −0.123+/−0.01 to −0.065+/−0.01; N=6). Selective inhibition of extracellular carbonic anhydrase activity using a low intravascular dose (1.3 mg kg-1) of the inhibitor benzolamide caused a significant reduction in the acid-base disequilibrium after 5 min (from −0.11+/−0.01 to −0.07+/−0. 01; N=14). These results demonstrate that the expired water acid-base disequilibrium originates, at least in part, from excretory CO2 and that extracellular carbonic anhydrase in dogfish may have a significant role in carbon dioxide excretion. However, externally oriented carbonic anhydrase (if present in dogfish) plays no role in catalysing the hydration of the excretory CO2 in water flowing over the gills and thus is unlikely to facilitate CO2 excretion.

Acid-base-catalyzed hydration of acetaldehyde. Buffer and metal ion catalysis

1967 ◽  
Vol 71 (10) ◽  
pp. 3113-3120 ◽  
Author(s):  
Yeshayau Pocker ◽  
John E. Meany
Keyword(s):  
Metal Ion ◽  
Acid Base ◽  
Metal Ion Catalysis

scholarly journals Contrast‐enhanced ultrasound imaging can be used to evaluate fetal cerebral perfusion: potential implications for fetal surgery

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Kendall M. Lawrence ◽  
Barbara E. Coons ◽  
Anush Sridharan ◽  
Avery C. Rossidis ◽  
Marcus G. Davey ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Cerebral Perfusion ◽  
Fetal Surgery ◽  
Time Dependent ◽  
Contrast Enhanced Ultrasound ◽  
Acid Base ◽  
Fetal Sheep ◽  
Contrast Enhanced ◽  
Support Device ◽  
Acid Base Status

Abstract Background Fetal surgery is increasingly performed to correct congenital defects. Currently, fetal brain perfusion cannot be assessed intra-operatively. The purpose of this study was to determine if contrast-enhanced ultrasound (CEUS) could be used to monitor fetal cerebral perfusion during fetal surgery and if parameters correlate with fetal hemodynamics or acid/base status. Methods Cannulated fetal sheep were insufflated with carbon dioxide gas in an extra-uterine support device and in utero to mimic fetal surgery. Fetal heart rate, mean arterial pressure, and arterial blood gases were serially measured. CEUS examinations of the brain were performed and time-dependent metrics were quantified to evaluate perfusion. The relationships between measured parameters were determined with mixed linear effects models or two-way repeated measures analysis of variance. Results 6 fetal sheep (113 ± 5 days) insufflated at multiple time-points (n = 20 experiments) in an extra-uterine support device demonstrated significant correlations between time-dependent perfusion parameters and fetal pH and carbon dioxide levels. In utero, 4 insufflated fetuses (105 ± 1 days) developed hypercarbic acidosis and had reductions in cerebral perfusion parameters compared to age-matched controls (n = 3). There was no significant relationship between cerebral perfusion parameters and fetal hemodynamics. Conclusions CEUS-derived cerebral perfusion parameters can be measured during simulated fetal surgery and strongly correlate with fetal acid/base status.

Metal Ion Catalysis in the Hydrolysis of Potassium Ethyl Oxalate

Nature ◽  
1964 ◽  
Vol 204 (4964) ◽  
pp. 1189-1190
Author(s):  
ROBERT W. HAY ◽  
NEIL J. WALKER
Keyword(s):  
Metal Ion ◽  
Metal Ion Catalysis ◽  
Hydrolysis Of
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