Journal of Applied Physiology, Vol 42, Issue 6 941-945, Copyright © 1977 by American Physiological Society
Effect of osmolality on red blood cell viscosity and transit through the lung
R. M. Effros, R. S. Chang and P. Silverman
The mean transit times of labeled red blood cells and albumin were compared
in eight isolated rabbit lungs perfused with physiological albumin
solutions. The osmolality of these solutions was adjusted by altering the
concentration of sodium chloride. The ratios of the mean transit times of
injected red blood cells to those of albumin increased as perfusion
osmolality increased from hypotonic to isotonic and from isotonic to
hypertonic levels. This change occurred despite a decline in pulmonary
vascular resistance and red blood cell size as osmolality was increased.
Red blood cell viscosity (determined with a cone-plate viscometer)
increased with osmolality and it was concluded that this change of
viscosity impaired the relative rate of red blood cell transit through the
lungs. Passage of red blood cells through rigid homoporous membranes
appeared to be related primarily to red cell size rather than vascosity.
These observations suggest that both red blood cell viscosity and capillary
distensibility play an important role in determining the velocity of red
blood cells through the capillaries.
