RESUMEN
Ultrafiltration and gel chromatography on Sephadex G-75 have revealed no evidence of ascorbate-binding to protein components of the soluble fraction derived from a tissue homogenate of rat cerebellum. Furthermore, partition studies have failed to detect any binding of ascorbic acid to structural components of rat cerebellum, as the ascorbate content of cerebellar tissue exhibited linear dependence upon the concentration of free vitamin in the surrounding medium (0.1 M phosphate, pH 6.5). The accumulation of ascorbic acid in rat cerebellum is discussed, therefore, in terms of an elevated intracellular concentration maintained by active transport of the vitamin across cerebellar tissue membranes.
Asunto(s)
Ácido Ascórbico/farmacocinética , Cerebelo/metabolismo , Animales , Transporte Biológico Activo , Femenino , Unión Proteica , Ratas , Ratas Endogámicas , UltrafiltraciónRESUMEN
The level of ascorbic acid in the brain of growing rats was not influenced by efforts to accelerate neural activity. Treatments used to depress neural activity included thyroidectomy which produced a 13%-20% loss of ascorbic acid in cortical and cerebellar tissue and diazepam which produced a significant rise in the cerebellum. Ethanol and barbital were without effect.
Asunto(s)
Ácido Ascórbico/metabolismo , Encéfalo/fisiología , Animales , Barbital/farmacología , Encéfalo/efectos de los fármacos , Cafeína/farmacología , Diazepam/farmacología , Ambiente , Etanol/farmacología , Masculino , Ratas , TiroidectomíaRESUMEN
Ultrafiltration has been used to investigate the interaction of ascorbate with bovine serum albumin in 0.1 M sodium phosphate buffer, pH 6.5. The results are interpreted in terms of the binding of ascorbate to four equivalent and independent protein sites, governed by an intrinsic association constant of 2 600 +/- 700 M-1 at 20 degrees C, thereby providing evidence for specificity of the interaction over a range of vitamin concentration (0.08-1.5 mM) pertinent to the physiological situation.
Asunto(s)
Ácido Ascórbico/metabolismo , Albúmina Sérica Bovina/metabolismo , Animales , Sitios de Unión , Bovinos , UltrafiltraciónRESUMEN
Large amounts of ascorbic acid were readily removed from neural tissue by washing with warmed saline solutions. In areas where the original level was highest, such as cortex and cerebellum, a higher percentage was removed than from areas of lower concentration, such as pons-medulla. The residual level in both types of tissue was similar. During scurvy, the ascorbic acid retained in the guinea pig brain is more readily removed by washing than is that of the normal brain.
Asunto(s)
Ácido Ascórbico/análisis , Química Encefálica , ADN/análisis , Animales , Cerebelo/análisis , Corteza Cerebral/análisis , Cobayas , Masculino , Bulbo Raquídeo/análisis , Puente/análisis , Cloruro de SodioRESUMEN
About a fifth of the ascorbic acid is readily lost from intestinal tissue during handling procedures such as washing with saline and blotting. Further losses occur during incubation in Krebs-phosphate saline; after 10 min strips of intestine retained 80% of their original ascorbic acid content and chopped tissue only 50%. This suggests that some of the intestinal ascorbic acid is very loosely held in the tissue. The small intestine is capable to accumulating double the normal amount of ascorbic acid when animals are dosed intramuscularly and retains some ascorbic acid (0.7 to 5 microgram/mg DNA) even when the animals' body stores are depleted.