Endothelial Metabolism Research Articles

ALKALINE PHOSPHATASE ACTIVITY IN CEREBRAL BLOOD VESSELS OF SPONTANEOUSLY HYPERTENSIVE RAT : The Second Report of Enzyme Histochemical Studies of SHR Brain

Alkaline phosphatase activity in the cerebral vessel wall of SHR was examined histochemically. In the control rats, the enzyme activity was observed in the adventitia and in the endothelial cells at the bifurcation on the arterial system and capillaries, while in SHR, positive alkaline phosphatase activity appeared in the endothelial cells also of places other than branchings. This positive activity was found in the early hypertensive stage 8 week old SHR and increased with age. The relationship of alkaline phosphatase activity and increased endothelial permeability and metabolism due to hypertension was discussed.

Elimination of anions derived from glucose metabolism as substrates for the fluid pump of rabbit corneal endothelium

Corneal endothelial metabolism was studied to discover whether the cells might synthesize any anion from glucose at rates sufficient to account for the fluid pump. They do not. Lactate is synthesized at a rate of 0·1 μEq/cm 2/hr and labellein, a polyanion of about 1500 daltons, at 0·013 μEq/cm 2/hr whereas an ion driven fluid pump would require an extrusion rate of about 1 μEq/cm 2/hr. There is no evidence for gluconeogenesis from lactate in the endothelium.

WATER PERMEABILITY OF THE LIVING CORNEA.

It has been proposed that a primary water pump across the cornea might provide the means by which the epithelial or endothelial metabolism keeps the cornea unswollen and transparent. 1,2 Some data have been published which could be interpreted as evidence for a water pump acting across the endothelium. 3 The cornea's permeability to water could also influence intraocular dynamics if there were a significant net transport of water into or out of the eye by active transport or by the normal hydrostatic pressure gradient. Cogan and Kinsey measured water flux across the excised cat cornea using D 2 O as a tracer. 4,5 No attempt was made in these studies to determine whether the corneas were alive and functioning. It is quite probable that their preparations were dead, and therefore, if an active corneal water transport exists, these corneas would not have exhibited it. Potts tried to measure the