phosphorus-radioisotopes and Starvation

A single administration of 2-allyl-2-isopropylacetamide, a porphyrinogenic drug, enhanced the 32P-labelling of nucleoplasmic as well as cytoplasmic poly(A)-containing RNA in rat liver. The synthesis of total microsomal RNA is only marginally increased under these conditions. The drug enhances the labelling of a variety of cytoplasmic poly(A)-containing RNA species, and this effect is counteracted by the simultaneous administration of haemin. 2-Allyl-2-isopropylacetamide also enhanced the release of RNA from the nucleus to the cytoplasm.

Topics: Acetamides; Allylisopropylacetamide; Animals; Biological Transport; Cell Nucleus; Cytoplasm; Electrophoresis, Polyacrylamide Gel; Hemin; Liver; Male; Microsomes, Liver; Phosphorus Radioisotopes; Poly A; Rats; RNA; Starvation

Topics: Alanine; Aminoisobutyric Acids; Animals; Bucladesine; Carbon Dioxide; Carbon Radioisotopes; Chromatography, Ion Exchange; Epinephrine; Fatty Acids, Nonesterified; Gluconeogenesis; Glycolysis; Kidney Tubules; Lactates; Liver; Male; Organ Specificity; Parathyroid Hormone; Phosphorus Radioisotopes; Starvation

Topics: Animals; Dose-Response Relationship, Drug; Freeze Drying; Gluconeogenesis; Guanosine Triphosphate; In Vitro Techniques; Kidney; Kidney Cortex; Kidney Tubules; Loop of Henle; Male; Nephrons; Organ Size; Phosphoenolpyruvate Carboxykinase (GTP); Phosphorus Radioisotopes; Rats; Starvation

1. Adenylate cyclase activity and patterns of insulin release in response to various concentrations of glucose were determined in islets of Langerhans isolated from starving, fed, or glucose-loaded rats. 2. Basal and glucagon-stimulated activities of adenylate cyclase were lower in islets from starved than from fed rats. The minimum glucose concentration required for stimulation of insulin secretion was higher, whereas the maximum secretory response to glucose was lower, in islets from starved than from fed rats. 3. Adenylate cyclase activity in islets of Langerhans obtained from fed rats loaded with glucose by intermittent intravenous or intraperitoneal injections over 5h was significantly higher than that seen in islets from normal fed rats. Islets obtained from glucose-loaded rats required a lower glucose concentration for stimulation of insulin secretion and attained a higher maximal response to glucose stimulation than those derived from fed rats. 4. Incubation in vitro of islets isolated from normal fed rats, for periods of 1 to 24h in the presence of high concentrations of glucose resulted in an activation of adenylate cyclase that occurred progressively from 2 to 7h and which was maintained during 24h of incubation. The increase of adenylate cyclase activity in isolated islets incubated for 4h in the presence of glucose was not prevented by addition of cycloheximide or actinomycin D. Galactose or 2-deoxyglucose was ineffective in increasing adenylate cyclase activity, and pyruvate (20mm) was less effective than glucose. 5. It is suggested that glucose or a glucose metabolite may exert long-term effects on islet cell adenylate cyclase.

Topics: Adenylyl Cyclases; Animals; Culture Techniques; Cycloheximide; Dactinomycin; Diet; Drug Interactions; Female; Galactose; Glucose; Insulin; Insulin Secretion; Islets of Langerhans; Mice; Phosphorus Radioisotopes; Pyruvates; Rats; Starvation; Theophylline