The nutrient supply of the chick visual system: responses to form and light deprivation.
Blood flow and uptake of two nutrient analogues have been studied in the neural retina, pigment epithelium and optic lobes of 5-7-day-old chicks after systemic administration of isotopically labeled compounds. The pigment epithelium accumulated the inert amino acid, alpha-aminoisobutyric acid, 6 times as effectively on a wet weight basis than did the neural retina or optic lobes. However, the neural retina was over 3 times as active in transport of deoxyglucose as was either the pigment epithelium or optic lobe. These differences could not be attributed to variations in blood flow since the penetrance of the freely diffusible antipyrine was low in the neural retina and roughly equal in the vascularized epithelium and optic lobes. Two days of unilateral eyelid suture significantly depressed blood flow and deoxyglucose uptake in the optic lobe innervated by the occluded eye. The neural retina of the eye receiving reduced light input also had a reduced level of deoxyglucose accumulation but the capacity to concentrate alpha-aminoisobutyrate was increased. The corresponding dark-adapted pigment epithelium had a major (48%) increase in the uptake of this inert amino acid. The data show that regional glucose utilization may not be directly proportional to blood flow or glucose diffusion rates. The non-vascularized neural retina possesses an unusually powerful glucose transport mechanism while the pigment epithelium has a high capacity for amino acid accumulation.
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002645:Chickens; D004292:Dominance, Cerebral / Q000502:physiology; D004734:Energy Metabolism; D005556:Form Perception / Q000502:physiology*; D010857:Pigment Epithelium of Eye / Q000502:physiology; D012160:Retina / Q000502:physiology*; D012683:Sensory Deprivation / Q000502:physiology*; D003336:Tectum Mesencephali / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*
D000596:Amino Acids; D001786:Blood Glucose