Hansen A J, Lund-Andersen H, Crone C
Acta Physiol Scand. 1977 Dec;101(4):438-45. doi: 10.1111/j.1748-1716.1977.tb06027.x.
The K+-permeability of the blood-brain barrier at the capillary level was estimated from determinations of brain extracellular K+-concentration in response to an isotonic bolus containing KCl injected into the carotid artery. A very low permeability appeared from the fact that the extracellular K+-concentration--measured by aid of K+-sensitive microelectrodes--remained unchanged during the passage of the bolus. An upper limit for the blood-brain barrier K+-permeability in the rat was estimated to be 2.8 X 10(-7) cm. with s-1.
