Effect of insulin on the glucose uptake of protozoa.

Insulin stimulates the glucose uptake of Tetrahymena pyriformis. This shows the presence of insulin receptors in Tetrahymena, consequently receptors may be present in a level of phylogenesis, where the natural contact between the given hormone and the cell is unnecessary and impossible.     

Sphingosine 1-phosphate increases glucose uptake through trans-activation of insulin receptor

Sphingosine 1-phosphate (S1P) is a bioactive lipid that acts through a family of G-protein-coupled receptors. Herein, we report evidence of a novel redox-based cross-talk between S1P and insulin signaling pathways. In skeletal muscle cells S1P, through engagement of its S1P₂ receptor, is found to produce a transient burst of reactive oxygen species through a calcium-dependent activation of the small GTPase Rac1. S1P-induced redox-signaling is sensed by protein tyrosine phosphatase-1B, the main negative regulator of insulin receptor phosphorylation, which undergoes oxidation and enzymatic inhibition. This redox-based inhibition of the phosphatase provokes a ligand-independent trans-phosphorylation of insulin receptor and a strong increase in glucose uptake. Our results propose a new role of S1P, recognizing the lipid as an insulin-mimetic cue and pointing at reactive oxygen species as critical regulators of the cross-talk between S1P and insulin pathways. Any possible implication of S1P-directed insulin signaling in diabetes and insulin resistance remains to be established.     

Effect of mecloqualone on the oxygen and glucose uptake by brain tissue in vitro

Resumen La mecloqualona inhibe in vitro, la respiración de cortes y homogenizados de cerebro, incrementando el consumo de glucosa; este último efecto no se produce cuando al medio de incubación se añaden 100 mM de potasio.     

Effect of vagal denervation on insulin release after oral and intravenous glucose

Zusammenfassung Perorale Glykosebelastung ergab bei vagotomierten Ratten Erhöhung des Blutglykosespiegels. Nach intravenöser Glykosezufuhr wurden niedrigere Werte von immunoreaktivem Insulin im Serum gefunden. Ebenso war der insulinogene Index bedeutend niedriger sowohl nach peroraler als auch nach intravenöser Glykosezufuhr. Vagotomie dürfte somit die glykosebedingte Insulinfreisetzung reduzieren.     

Effect of Ketamine hydrochloride on oxygen and glucose uptake by brain tissue in vitro

Resumen El clorhidrato de Ketamina (1×10^–3 M y 1×10^–4 M) incrementa el consumo de oxigeno de cortes de cerebro de rata incubados en Krebs-Ringer fosfato conteniendo 5 mM ó 100 mM de potasio. La droga no modifica el consumo de oxigeno de homogeneizado de cerebro total.     

Effect of gentamycin on insulin release and45Ca net uptake by isolated islets

Summary In isolated islets, gentamycin reduced both the⁴⁵Ca net uptake and insulin release induced by glucose, but failed to inhibit the insulin secretion provoked by the combination of Ba²⁺ and theophylline. This indicates that the inhibitory effect of gentamycin is due to a reduction of Ca²⁺ entry into B-cells instead of to a harmful effect upon the integrity of the effector system, responsible for the extrusion of the insulin containing granules.Supported by a Grant (No. 79/1872) from the São Paulo State Research Foundation (FAPESP), Brazil.     

Effect of chronic hypo and hypervitaminosis C on the brush border enzymes and the intestinal uptake of glucose and alanine

Summary Brush border sucrase and alkaline phosphatase activities are considerably enhanced in the intestine of ascorbic acid deficient guinea-pigs. Similar increase in the uptake of D-glucose and L-alanine also occurs in chronic vitamin C deficiency. However the permeability of D-glucose and L-alanine in the intestine of animals fed with large doses of vitamin C is severely depressed, with a reduction in the levels of sucrase and alkaline phosphatase activities.     

Effect of steviol and its structural analogues on glucose production and oxygen uptake in rat renal tubules

Summary The effect of several natural products ofStevia rebaudiana on glucose production and oxygen uptake in rat renal cortical tubules was investigated. Steviol, isosteviol and glucosilsteviol decreased glucose production and inhibited oxygen uptake. The sweet principle stevioside, and steviolbioside, however, were without effect on gluconeogenesis and oxygen uptake.     

Effect of steviol and its structural analogues on glucose production and oxygen uptake in rat renal tubules

The effect of several natural products of Stevia rebaudiana on glucose production and oxygen uptake in rat renal cortical tubules was investigated. Steviol, isosteviol and glucosilsteviol decreased glucose production and inhibited oxygen uptake. The sweet principle stevioside, and steviolbioside, however, were without effect on gluconeogenesis and oxygen uptake.     

Effect of chronic hypo and hypervitaminosis C on the brush border enzymes and the intestinal uptake of glucose and alanine.

Brush border sucrase and alkaline phosphatase activities are considerably enhanced in the intestine of ascorbic acid deficient guinea-pigs. Similar increase in the uptake of D-glucose and L-alanine also occurs in chronic vitamin C deficiency. However the permeability of D-glucose and L-alanine in the intestine of animals fed with large doses of vitamin C is severely depressed, with a reduction in the levels of sucrase and alkaline phosphatase activities.     

Action of insulinin vitro on the glucose uptake of the spinal cord of the rat

Résumé La moelle épinière ne paraît pas sensible à l'insulinein vitro si elle provient d'un animal décapité alors qu'elle l'est de façon significative (P < 0,01) si l'animal était anesthésié avec un mélange de CO₂/O₂ à 50%.

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Preliminary communication.     

Some thoughts on the importance of insulin in the regulation of the blood glucose level

Insulin can influence rates of glucose utilization by muscle and possibly other tissues via both direct and indirect effects. It can control the rate of fatty acid mobilization from adipose tissue and the rate of fatty acid oxidation in muscle, and the latter inhibits glucose utilization and oxidation. Insulin may influence the levels of insulin-like growth factors I and II, both of which have effects on rates of glucose utilization by muscle. The intertissue cycle between glucose and lactate — the Cori cycle, which is influenced by insulin — may provide another novel mechanism for control of blood glucose. How far other anti-insulin hormones affect these processes is not clear.     

Effect of hyperkalemia on insulin secretion

Summary The effect of hyperkalemia on insulin secretion remains undefined. We evaluated portal and peripheral insulin levels in anesthetized dogs after infusions of KCl. The mean maximal increase in peripheral plasma potassium at infusion rates of 0.2 mEq/kg/h was 0.68±0.20 mEq/l. There were no significant increases in either portal or peripheral insulin levels. In contrast, in six dogs whose plasma potassium concentration increased in each case by more than 2.0 mEq/l (infusion rate of 0.5 mEq/kg/h), portal insulin levels increased fivefold (p<0.05). We conclude that only marked increases in plasma potassium concentration stimulate pancreatic insulin secretion.     

Effect of hyperkalemia on insulin secretion

The effect of hyperkalemia on insulin secretion remains undefined. We evaluated portal and peripheral insulin levels in anesthetized dogs after infusions of KCl. The mean maximal increase in peripheral plasma potassium at infusion rates of 0.2 mEq/kg/h was 0.68 +/- 0.20 mEq/l. There were no significant increases in either portal or peripheral insulin levels. In contrast, in six dogs whose plasma potassium concentration increased in each case by more than 2.0 mEq/l (infusion rate of 0.5 mEq/kg/h), portal insulin levels increased fivefold (p less than 0.05). We concluded that only marked increases in plasma potassium concentration stimulate pancreatic insulin secretion.     

Influence ofin vitro added thyroxin upon the glucose uptake of the rat diaphragm

Résumé 1^o La consommation de glucose du diaphragme isolé de rat incubé dans la solution deKrebs-Henseleit glucosée est constamment accrue par la thyroxine ajoutée au milieu.2^o La concentration optima pour ces déterminations était de 10^–7 à 10^–6 de thyroxine.