[Various aspects of the existing relationship between retinal neuronal function, oxidative metabolism and the constant O2 supply by the microcirculation].

Retinal excitation implies transmembrane ion movement in the retinal neurones. In order to maintain excitability, the neurones utilize energy derived from the hydrolysis of ATP. ATP is produced in the mitochondria, which consume O2 and carbohydrates for this purpose. Thus, O2 consumption is essential for maintaining ATP in the retinal neurons and, therefore, for maintaining excitability. O2 is delivered to the retinal mitochondria by the microcirculation, where variations of the blood flow cause dramatic fluctuations in the local PO2 in the tissue. The retinal blood flow can be impaired by experimental changes in the pH of the glial cells surrounding the arterioles. According to a hypothesis, intraglial pH modulates the release of a mediator (prostaglandins) which in turn acts on the smooth musculature of the arteriole wall and thus controls vascular motility.