scholarly journals Red blood cell carbonic anhydrase mediates oxygen delivery via the Root effect in red drum

2020 ◽  
Vol 223 (22) ◽  
pp. jeb232991
Author(s):  
Angelina M. Dichiera ◽  
Andrew J. Esbaugh

ABSTRACTOxygen (O2) and carbon dioxide (CO2) transport are tightly coupled in many fishes as a result of the presence of Root effect hemoglobins (Hb), whereby reduced pH reduces O2 binding even at high O2 tensions. Red blood cell carbonic anhydrase (RBC CA) activity limits the rate of intracellular acidification, yet its role in O2 delivery has been downplayed. We developed an in vitro assay to manipulate RBC CA activity while measuring Hb-O2 offloading following a physiologically relevant CO2-induced acidification. RBC CA activity in red drum (Sciaenops ocellatus) was inhibited with ethoxzolamide by 53.7±0.5%, which prompted a significant reduction in O2 offloading rate by 54.3±5.4% (P=0.0206, two-tailed paired t-test; n=7). Conversely, a 2.03-fold increase in RBC CA activity prompted a 2.14-fold increase in O2 offloading rate (P<0.001, two-tailed paired t-test; n=8). This approximately 1:1 relationship between RBC CA activity and Hb-O2 offloading rate coincided with a similar allometric scaling exponent for RBC CA activity and maximum metabolic rate. Together, our data suggest that RBC CA is rate limiting for O2 delivery in red drum.

1995 ◽  
Vol 198 (1) ◽  
pp. 31-38 ◽  
Author(s):  
J Lessard ◽  
A Val ◽  
S Aota ◽  
D Randall

Carbonic anhydrase (CA) is absent from the plasma of vertebrates. In vitro, CA in fish plasma will short-circuit the effect of catecholamines, which is to increase red blood cell (RBC) pH and volume, both of which enhance the affinity of hemoglobin for O2. CA was infused into trout for a period of 6 h and injected after 48 h, during which the animal was submitted to deep hypoxia (PO2=30&shy;35 mmHg; 4.0&shy;4.7 kPa). O2 content, lactate content, catecholamine levels, hematocrit, hemoglobin concentration and pHi were similar to those in the saline-infused control group. In contrast, cell volume was significantly higher and pHe, total CO2 content and organic phosphate levels were significantly lower than in the control group. The concentration of CA was not high enough completely to short-circuit the increase in pHi and red blood cell volume caused by catecholamines. The lower pHe in the CA-infused animals could enhance the activity of the Na+/H+ pump, which would keep the nucleotide triphosphate levels low. pH is a balance between acid loading at the muscle and acid excretion at the gills or the kidneys; we cannot distinguish between which of these resulted in a decrease of plasma pH. In conclusion, CA in plasma did not cause the expected reduction in blood oxygen content but did have a marked effect on plasma total CO2 content.


1971 ◽  
Vol 10 (04) ◽  
pp. 299-304
Author(s):  
József Takó ◽  
János Fischer ◽  
Jusztina Juhász ◽  
Ilona Sztraka ◽  
István Kapus ◽  
...  

SummaryThe results of thyroid function tests have been compared with data on the thyroxine-binding capacity of plasma proteins in hyper-, hypo- and euthyroid cases, the latter including women taking oral contraceptives (Infecundin). It was found that there exists a significant correlation of exponential nature between the in vitro red blood cell 125I-triiodothyronine uptake (RCU) and the free thyroxine-binding capacity of the thyroxine-inding globulin (TBG).


2011 ◽  
Vol 1 (2) ◽  
pp. 173-181
Author(s):  
Laurence Guyonneau-Harmand ◽  
Luc Douay

Author(s):  
Adam Attila Matrai ◽  
Gabor Varga ◽  
Bence Tanczos ◽  
Barbara Barath ◽  
Adam Varga ◽  
...  

BACKGROUND: The effects of temperature on micro-rheological variables have not been completely revealed yet. OBJECTIVE: To investigate micro-rheological effects of heat treatment in human, rat, dog, and porcine blood samples. METHODS: Red blood cell (RBC) - buffer suspensions were prepared and immersed in a 37, 40, and 43°C heat-controlled water bath for 10 minutes. Deformability, as well as mechanical stability of RBCs were measured in ektacytometer. These tests were also examined in whole blood samples at various temperatures, gradually between 37 and 45°C in the ektacytometer. RESULTS: RBC deformability significantly worsened in the samples treated at 40 and 43°C degrees, more expressed in human, porcine, rat, and in smaller degree in canine samples. The way of heating (incubation vs. ektacytometer temperation) and the composition of the sample (RBC-PBS suspension or whole blood) resulted in the different magnitude of RBC deformability deterioration. Heating affected RBC membrane (mechanical) stability, showing controversial alterations. CONCLUSION: Significant changes occur in RBC deformability by increasing temperature, showing inter-species differences. The magnitude of alterations is depending on the way of heating and the composition of the sample. The results may contribute to better understanding the micro-rheological deterioration in hyperthermia or fever.


PLoS ONE ◽  
2015 ◽  
Vol 10 (8) ◽  
pp. e0136885 ◽  
Author(s):  
Stéphane Kerbrat ◽  
Benoit Vingert ◽  
Marie-Pierre Junier ◽  
Flavia Castellano ◽  
François Renault-Mihara ◽  
...  

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