AJP - Regulatory, Integrative and Comparative Physiology, Vol 234, Issue 1 52-R60, Copyright © 1978 by American Physiological Society
Comparative aspects of brain barrier systems for nonelectrolytes
H. F. Cserr, J. D. Fenstermacher and D. P. Rall
Blood-brain and blood-CSF barriers to inulin were compared in 11 vertebrate
species. Twenty hours after systemic administration, [14C]inulin penetrated
into the central nervous system to an equivalent extent in mudpuppy,
salamander (adult and larval), red sculpin, big skate, little skate,
southern stingray, and Atlantic stingray with values for RB (dpm/g brain
divided by dpm/ml plasma) in the range 0.01- 0.04 and for RCSF (dpm/ml CSF
divided by dpm/ml plasma) from 0.02 to 0.04. These values are similar to
those reported for mammals. For dogfish, nurse shark, and lemon shark, RB
ranged from 0.04 to 0.09 and RCSF from 0.08 to 0.29 and for hagfish
RB=0.12, indicating that barrier systems to inulin are poorly developed in
sharks and possibly absent in hagfish. Analyses of radiolabeled urea and
sucrose penetration into brain and CSF revealed further differences in
shark barrier function. Brain barriers to insulin in dogfish and little
skate developed with age; in nurse shark there was no detectable change in
the inulin ratios over the weight range, 0.2-110 kg.
