PMID- 27777410
OWN - NLM
STAT- MEDLINE
DCOM- 20180430
LR  - 20181113
IS  - 2045-2322 (Electronic)
IS  - 2045-2322 (Linking)
VI  - 6
DP  - 2016 Oct 25
TI  - Red blood cell thickness is evolutionarily constrained by slow, 
      hemoglobin-restricted diffusion in cytoplasm.
PG  - 36018
LID - 10.1038/srep36018 [doi]
LID - 36018
AB  - During capillary transit, red blood cells (RBCs) must exchange large quantities 
      of CO(2) and O(2) in typically less than one second, but the degree to which this 
      is rate-limited by diffusion through cytoplasm is not known. Gas diffusivity is 
      intuitively assumed to be fast and this would imply that the intracellular 
      path-length, defined by RBC shape, is not a factor that could meaningfully 
      compromise physiology. Here, we evaluated CO(2) diffusivity (D(CO2)) in RBCs and 
      related our results to cell shape. D(CO2) inside RBCs was determined by 
      fluorescence imaging of [H(+)] dynamics in cells under superfusion. This method 
      is based on the principle that H(+) diffusion is facilitated by CO(2)/HCO(3)(-) 
      buffer and thus provides a read-out of D(CO2). By imaging the spread of H(+) ions 
      from a photochemically-activated source (6-nitroveratraldehyde), D(CO2) in human 
      RBCs was calculated to be only 5% of the rate in water. Measurements on RBCs 
      containing different hemoglobin concentrations demonstrated a halving of D(CO2) 
      with every 75 g/L increase in mean corpuscular hemoglobin concentration (MCHC). 
      Thus, to compensate for highly-restricted cytoplasmic diffusion, RBC thickness 
      must be reduced as appropriate for its MCHC. This can explain the inverse 
      relationship between MCHC and RBC thickness determined from >250 animal species.
FAU - Richardson, Sarah L
AU  - Richardson SL
AD  - Department of Physiology, Anatomy and Genetics, Oxford OX1 3PT, European Union, 
      United Kingdom.
FAU - Swietach, Pawel
AU  - Swietach P
AD  - Department of Physiology, Anatomy and Genetics, Oxford OX1 3PT, European Union, 
      United Kingdom.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20161025
PL  - England
TA  - Sci Rep
JT  - Scientific reports
JID - 101563288
RN  - 0 (Bicarbonates)
RN  - 0 (Hemoglobins)
RN  - 142M471B3J (Carbon Dioxide)
RN  - S88TT14065 (Oxygen)
SB  - IM
MH  - Animals
MH  - Bicarbonates/*blood
MH  - Biological Transport
MH  - Camelids, New World
MH  - Carbon Dioxide/*blood
MH  - Cell Shape/physiology
MH  - Chickens
MH  - Diffusion
MH  - Erythrocyte Indices/*physiology
MH  - Erythrocytes/*physiology
MH  - Hemoglobins/metabolism
MH  - Humans
MH  - Oxygen/blood
MH  - Pulmonary Gas Exchange/*physiology
MH  - Xenopus laevis
PMC - PMC5078773
EDAT- 2016/10/26 06:00
MHDA- 2018/05/01 06:00
PMCR- 2016/10/25
CRDT- 2016/10/26 06:00
PHST- 2016/06/22 00:00 [received]
PHST- 2016/10/11 00:00 [accepted]
PHST- 2016/10/26 06:00 [pubmed]
PHST- 2018/05/01 06:00 [medline]
PHST- 2016/10/26 06:00 [entrez]
PHST- 2016/10/25 00:00 [pmc-release]
AID - srep36018 [pii]
AID - 10.1038/srep36018 [doi]
PST - epublish
SO  - Sci Rep. 2016 Oct 25;6:36018. doi: 10.1038/srep36018.