Glutamine-enriched enteral diet increases renal arginine production

Arginine (Arg) is generated in the kidney by the conversion of circulating citrulline. The most important source for circulating citrulline is the metabolism of glutamine (Gln) by the gut. In this study, we investigated the influence of an enteral diet enriched with Gln on renal Arg synthesis in the rat. Rats were fed a 12.5% Gln-enriched diet or an isocaloric, isonitrogenous control diet for 14 days. Kidney plasma flow and arterial and renal venous plasma levels of a number of amino acids were measured, and kidney amino acid fluxes were calculated. Compared with the control diet, Gln enrichment resulted in significantly higher arterial plasma levels of circulating citrulline (30%, p <.0001) and Arg (31%, p <.0005). The uptake of circulating citrulline and the subsequent production of Arg by the kidneys were significantly higher in the Gln-enriched group (40% and 38%, respectively) and showed an equimolar relationship in both the control (r = .84, p <.0001) and the Gln-enriched group (r = .83, p <.0001). The findings indicate that enteral Gln supplementation caused significantly increased arterial plasma levels of Arg as a result of increased renal Arg production from circulating citrulline. Considering the multiple important biologic properties of Arg, the reported beneficial effects of Gln in catabolic states might be explained in part by increased renal Arg productio

Glutamine-enriched enteral diet increases splanchnic blood flow in the rat

The hemodynamic consequences of glutamine (Gln)-enriched nutrition have not been investigated. This study investigates the effects of a Gln-enriched enteral diet on organ blood flows and systemic hemodynamics. Male Fischer 344 rats (n = 24) were randomized to a group that received a 12.5% (wt/wt) Gln-enriched enteral diet or an isonitrogenous isocaloric control diet for 14 days. Blood flow measurements were performed at day 16 using 46Sc-labeled microspheres. In the Gln-enriched group, higher organ blood flows were measured in the stomach (51%), the pancreas (35%), small intestine (32%), and colon (55%), compared with controls. No differences were found in systemic hemodynamic parameters between the control and Gln-supplemented groups. A possible role for nitric oxide in this splanchnic vasodilation was investigated. Daily urinary nitrate excretion was measured during the study but showed no significant differences between the control and Gln-fed animals. No differences were found in plasma levels of the vasodilating hormone glucagon between the groups. These results show that a Gln-enriched enteral diet increased splanchnic blood flow, which was not mediated by pancreatic glucagon or increased nitric oxide production as determined by urinary nitrate excretio

An Empirical Analysis of Liquidity and Its Determinants in the German Intraday Market for Electricity

This paper presents a theoretical and empirical analysis of liquidity in the German intraday market for electricity. Two models that aim at explaining intraday liquidity are developed. The first model considers the fundamental merit-order and intraday adjustment needs as the drivers of liquidity in a perfectly competitive market. The second model relaxes the assumption of perfect competition in the intraday market and assumes that the trading behavior of profit maximizing market participants influences the liquidity provision. The relevance of commonly used liquidity indicators like the bid ask-spread, resiliency, market depth, price variance, delay and search costs as well as trading volume and the number of trades are analyzed with respect to both models of liquidity. The empirical findings indicate that liquidity in the German intraday market can be explained by the trading model while the purely fundamental model is rejected