Intravenous Administration Of Amino Acids Research Articles

Administration of Intravenous Amino Acids Attenuates Postoperative Hypothermia in Patients Undergoing Percutaneous Nephrolithotomy.

Amino acids attenuate hypothermia during the perioperative period by increasing thermogenesis and stimulating energy consumption. Percutaneous nephrolithotomy (PCNL) induces profound hypothermia owing to the use of large volumes of irrigating fluids. The role of amino acids in this group of surgeries for hypothermia and shivering prevention has been evaluated in this study because there is no available literature of concern. This prospective randomised controlled trial was conducted in patients undergoing PCNL. Group A received amino acids at 60 mL h-1 an hour before surgery until the end of surgery. Group C received normal saline infusion. Perioperative nasopharyngeal temperature, haemodynamics, and postoperative shivering were recorded. Although there was no significant difference in temperature in the intraoperative period, postoperative decrease in the temperature was less in the amino acid group. In the postoperative period, 2 patients in the amino acid group and 11 patients in the control group experienced shivering. Intravenous administration of amino acids attenuated postoperative hypothermia and reduced shivering in patients undergoing PCNL without any adverse effects.

Intravenous nutrients for preventing inadvertent perioperative hypothermia in adults.

Inadvertent perioperative hypothermia (a drop in core temperature to below 36°C) occurs because normal temperature regulation is disrupted during surgery, mainly because of the effects of anaesthetic drugs and exposure of the skin for prolonged periods. Many different ways of maintaining body temperature have been proposed, one of which involves administration of intravenous nutrients during the perioperative period that may reduce heat loss by increasing metabolism, thereby increasing heat production. To assess the effectiveness of preoperative or intraoperative intravenous nutrients in preventing perioperative hypothermia and its complications during surgery in adults. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; November 2015) in the Cochrane Library; MEDLINE, Ovid SP (1956 to November 2015); Embase, Ovid SP (1982 to November 2015); the Institute for Scientific Information (ISI) Web of Science (1950 to November 2015); and the Cumulative Index to Nursing and Allied Health Literature (CINAHL, EBSCO host; 1980 to November 2015), as well as the reference lists of identified articles. We also searched the Current Controlled Trials website and ClincalTrials.gov. Randomized controlled trials (RCTs) of intravenous nutrients compared with control or other interventions given to maintain normothermia in adults undergoing surgery. Two review authors extracted data and assessed risk of bias for each included trial, and a third review author checked details if necessary. We contacted some study authors to request additional information. We included 14 trials (n = 565), 13 (n = 525) of which compared intravenous administration of amino acids to a control (usually saline solution or Ringer's lactate). The remaining trial (n = 40) compared intravenous administration of fructose versus a control. We noted much variation in these trials, which used different types of surgery, variable durations of surgery, and different types of participants. Most trials were at high or unclear risk of bias owing to inappropriate or unclear randomization methods, and to unclear participant and assessor blinding. This may have influenced results, but it is unclear how results might have been influenced.No trials reported any of our prespecified primary outcomes, which were risk of hypothermia and major cardiovascular events. Therefore, we decided to analyse data related to core body temperature instead as a primary outcome. It was not possible to conduct meta-analysis of data related to amino acid infusion for the 60-minute and 120-minute time points, as we observed significant statistical heterogeneity in the results. Some trials showed that higher temperatures were associated with amino acids, but not all trials reported statistically significant results, and some trials reported the opposite result, where the amino acid group had a lower core temperature than the control group. It was possible to conduct meta-analysis for six studies (n = 249) that provided data relating to the end of surgery. Amino acids led to a statistically significant increase in core temperature in comparison to those receiving control (MD = 0.46°C 95% CI 0.33 to 0.59; I2 0.0%; random-effects; moderate quality evidence).Three trials (n = 155) reported shivering as an outcome. Meta-analysis did not show a clear effect, and so it is uncertain whether amino acids reduce the risk of shivering (RR 0.36, 95% CI 0.13 to 1.00; I2 = 93%; random-effects model; very low-quality evidence). Intravenous amino acids may keep participants up to a half-degree C warmer than the control. This difference was statistically significant at the end of surgery, but not at other time points. However, the clinical importance of this finding remains unclear. It is also unclear whether amino acids have any effect on the risk of shivering and if intravenous nutrients confer any other benefits or harms, as high-quality data about these outcomes are lacking.

Effect of intrathecal meperidine and intravenous amino acid infusion in reducing intraoperative shivering during spinal anesthesia: A prospective randomized trial

BackgroundThis is a prospective randomized double blind study to compare the efficacy of intravenous amino acid infusion versus meperidine added to intrathecal hyperbaric bupivacaine in reducing intraoperative shivering in parturient undergoing elective cesarean section under spinal anesthesia.MethodsSixty patients were randomly allocated into two groups. Group (A) (Amino-acid) (n = 30) who received 2 ml of 0.5% hyperbaric bupivacaine and ½ ml normal saline 0.9% (total volume 2.5 ml) intrathecal with intravenous administration of amino acids (Aminoven 5%, Fresenius Kabi), infused at rate 3 ml/kg/h with the start of spinal anesthesia and throughout the operation. Group (M) (meperidine) (n = 30) who received 2 ml of 0.5% hyperbaric bupivacaine with 10 mg meperidine in ½ ml volume (total volume 2.5 ml) intrathecal with intravenous administration of normal saline 0.9% at 3 ml/kg/h with the start of spinal anesthesia.ResultsGroup (A) showed significantly higher core temperature from 20 to 60 min than group (M) (p < 0.001), also the amino acid group (group A) had a significantly higher skin temperature from 10 to 60 min during surgery, and lower shivering score than group (M) (p < 0.05), during spinal anesthesia in parturients undergoing cesarean section.ConclusionAmino acids infusion decreased the incidence of shivering, increased peripheral and core temperature than intrathecal meperidine, which seems a safer alternative, more effective with lesser side effects than intrathecal meperidine in parturients undergoing cesarean section under spinal anesthesia.

Adaptive regulation of amino acid metabolism on early parenteral lipid and high-dose amino acid administration in VLBW infants – A randomized, controlled trial

An anabolic state can be achieved upon intravenous amino acid administration during the immediate postnatal phase despite a low energy intake. The optimal dosing of amino acid and energy intake has yet to be established. The aim was to quantify the efficacy of early initiation of parenteral lipids and increased amounts of amino acids on metabolism and protein accretion in very low birth weight infants. 28 very low birth weight infants were randomized to receive parenteral nutrition with glucose and either 2.4gamino acids/(kg·d) (control group), 2.4gamino acids/(kg·d) plus 2-3glipid/(kg·d) (AA+lipid group), or 3.6gamino acids/(kg·d) plus 2-3glipid/(kg·d) (high AA+lipid group) from birth onward. On postnatal day 2, we performed a stable isotope study with [1-(13)C]phenylalanine, [ring-D4]tyrosine, [U-(13)C6,(15)N]leucine, and [methyl-D3]α-ketoisocaproic acid to quantify intermediate amino acid metabolism. The addition of lipids only had no effect on phenylalanine metabolism, whereas the addition of both lipids and additional amino acids increased the amount of phenylalanine used for protein synthesis. In addition, high amino acid intake significantly increased the rate of hydroxylation of phenylalanine to tyrosine, increasing the availability of tyrosine for protein synthesis. However, it also increased urea concentrations. Increasing energy intake from 40 to 60kcal/(kg·d) did not increase protein efficiency as measured by phenylalanine kinetics. The leucine data were difficult to interpret due to the wide range of results and inconsistency in the data between the phenylalanine and leucine models. High amino acid and energy intakes from birth onwards result in a more anabolic state in very low birth weight infants, but at the expense of higher urea concentrations, which reflects a higher amino acid oxidation. Long-term outcome data should reveal whether this policy deserves routine implementation. This trial was registered at www.trialregister.nl, trial number NTR1445, name Nutritional Intervention for Preterm Infants-2.

Behcet's Disease (Syndrome) with Myalgia and Its Response to Intravenous Amino Acids: A Case Series

To present a case series of patients with refractory Behçet's disease who presented with myalgia and with signs such as mouth and genital ulcerations and skin lesions and were treated with intravenous amino acids. Case series of patients with Behçet's Disease who presented to a clinical practice devoted to Pain Medicine and Neurology between 2000 and 2009 for treatment of myalgia. All patients were treated with prednisone 60 mg by mouth daily for exacerbations of their disease. When this failed, eleven patients received intravenous administration of amino acids (Procalamine). Ten of eleven patients had a complete resolution of their Behçet's exacerbation, including myalgia; their painful ulcers became painless and began to heal with the infusion of amino acids for 2-5 days. Physicians treating myalgia should observe for signs of Behçet's disease, such as oral and genital ulcerations, and consider intravenous amino acids if steroids are not effective.

Effects of Two Different Doses of Amino Acid Supplementation on Growth and Blood Amino Acid Levels in Premature Neonates Admitted to the Neonatal Intensive Care Unit: A Randomized, Controlled Trial

OBJECTIVES. The goal was to measure the effects of 2 distinct strategies for parenteral nutrition on neonatal growth and blood amino acid profiles. METHODS. In a multicenter trial (n = 11 sites), we randomly allocated premature (23–29 weeks and 6 days of gestation) neonates to 1 of 2 approaches to intravenous amino acid administration. In one group, amino acid supplementation was started at 1.0 g/kg per day and advanced by 0.5 g/kg per day to a maximum of 2.5 g/kg per day (2.5 g/kg per day group). The other group received amino acids starting at 1.5 g/kg per day and advancing by 1.0 g/kg per day to a maximum of 3.5 g/kg per day (3.5 g/kg per day group). Filter paper blood spots were obtained from each infant on the day of random assignment and on days 7 and 28 of age, to monitor blood amino acid levels. RESULTS. We enrolled 122 neonates (64 in the 3.5 g/kg per day group and 58 in the 2.5 g/kg per day group). There were no differences in demographic or baseline characteristics between the 2 treatment groups. There was no significant difference in growth by day 28 after birth (median weight gain: 12.9 and 11.4 g/kg per day for the 3.5 and 2.5 g/kg per day groups, respectively), and the incidences of secondary morbidities were similar in the 2 groups. On day 7, blood levels of several amino acids and the serum urea nitrogen level were higher in the 3.5 g/kg per day group, compared with the 2.5 g/kg per day group; none of the amino acid levels were lower. CONCLUSIONS. Higher doses of amino acid supplementation did not improve neonatal growth and were associated with increased blood amino acid and urea nitrogen levels.

The influence of amino-acid supplementation, gestational age and time on thyroxine levels in premature neonates

Newborn screening laboratories vary in the values that are used to define congenital hypothyroidism. Defining congenital hypothyroidism is particularly complex in premature neonates because prematurely born infants often have a low free thyroxine value and low or normal TSH value, termed as transient hypothyroxinemia of prematurity. In a multicenter (n=11 sites) trial, we randomly allocated premature neonates with a gestational age of 23 to 29 and 6/7 weeks to one of two parenteral nutrition approaches. The primary objective of our trial was to measure the effect of two distinct strategies of parenteral nutrition on neonatal growth and blood amino acids. A protocol defined secondary aim of our clinical trial was the evaluation of the influence of gestational age, time and the degree of amino-acid supplementation on total thyroxine levels. We hypothesized that an increase of amino-acid supplementation would be associated with the normalization of serum amino acids and that this would improve thyroxine synthesis. Premature neonates (23 to 29 and 6/7 weeks) were randomly allocated to one of two approaches to intravenous amino-acid administration. In one group, amino-acid supplementation started at 1.0 g kg(-1) per day and advanced by 0.5 g kg(-1) per day to a maximum of 2.5 g kg(-1) per day (2.5 group). The other group received amino acids at 1.5 g kg(-1) per day and advanced by 1.0 g kg(-1) per day to a maximum of 3.5 g kg(-1) per day (3.5 group). Filter paper blood spots were obtained on the day of randomization, and on days 7 and 28 of age to monitor laboratory values. Enrollment included 122 neonates, 64 in the 3.5 group and 58 in the 2.5 group. There were no differences in demographics or baseline characteristics between the two treatment groups. There were no significant differences in thyroid levels at baseline, on days 7 and 28 between the two treatment groups. Growth was similar in both groups. It was noted that thyroxine levels changed over time and that the changes with time were greatest in the most preterm neonates. The degree of amino-acid supplementation does not influence thyroxine levels and both time from birth and gestational age do influence thyroxine levels.

Effects of Two Different Doses of Amino Acid Supplementation on Growth and Blood Amino Acid Levels in Premature Neonates Admitted to the Neonatal Intensive Care Unit: A Randomized, Controlled Trial

The goal was to measure the effects of 2 distinct strategies for parenteral nutrition on neonatal growth and blood amino acid profiles. In a multicenter trial (n = 11 sites), we randomly allocated premature (23-29 weeks and 6 days of gestation) neonates to 1 of 2 approaches to intravenous amino acid administration. In one group, amino acid supplementation was started at 1.0 g/kg per day and advanced by 0.5 g/kg per day to a maximum of 2.5 g/kg per day (2.5 g/kg per day group). The other group received amino acids starting at 1.5 g/kg per day and advancing by 1.0 g/kg per day to a maximum of 3.5 g/kg per day (3.5 g/kg per day group). Filter paper blood spots were obtained from each infant on the day of random assignment and on days 7 and 28 of age, to monitor blood amino acid levels. We enrolled 122 neonates (64 in the 3.5 g/kg per day group and 58 in the 2.5 g/kg per day group). There were no differences in demographic or baseline characteristics between the 2 treatment groups. There was no significant difference in growth by day 28 after birth (median weight gain: 12.9 and 11.4 g/kg per day for the 3.5 and 2.5 g/kg per day groups, respectively), and the incidences of secondary morbidities were similar in the 2 groups. On day 7, blood levels of several amino acids and the serum urea nitrogen level were higher in the 3.5 g/kg per day group, compared with the 2.5 g/kg per day group; none of the amino acid levels were lower. Higher doses of amino acid supplementation did not improve neonatal growth and were associated with increased blood amino acid and urea nitrogen levels.

Renal response to an acute protein challenge in pregnant women with borderline hypertension

The renal reserve (RR), assessed after an oral protein challenge or the intravenous administration of amino acids, is still present in healthy pregnant women (NP), although resting glomerular filtration rate (GFR) and renal plasma flow (RPF) increase progressively throughout normal gestation. No studies have addressed this issue in hypertensive gravidas; the aim of this trial was to evaluate renal response to an acute protein load (PL) in NP and pregnant women with borderline hypertension (HP). Five NP, eight HP and eight healthy non-pregnant women (CG) were evaluated. After fasting overnight, all subjects received an oral water load (20 mL/kg of body weight), the urinary output was then replaced orally with equal volumes of water. After two 30 min periods, an 80 g PL was provided. Creatinine clearance (CCr) was measured every 30 min from 1 h before and for 4 h following PL. Participants remained recumbent during the study, bladder emptiness was assessed by ultrasound immediately after each micturition. Baseline CCr was taken as the average of two 30 min periods before PL and peak Ccr as the maximal CCr recorded thereafter. The groups were similar with regard to age, weight or gestation age. Baseline CCr (NP: 118.5+/-6.0, HP: 127.4+/-6.7 and CG: 99.8+/-2.9 mL/min, P=0.004 (CG vs NP and HP), increased after PL to NP: 223.5+/-9.8 to HP: 178.5+/-13 and to CG: 149.1+/-4.0 mL/min, P<0.0004 (CG vs HP, CG vs NP and NP vs HP)). Peak minus baseline CCr was 97.3+/-10.1; 46.3+/-12.7 and 48.3+/-4.8 for NP, HP and CG, respectively (P<0.006 HP vs CG and NP). The peak CCr was obtained significantly earlier in both pregnant groups (Period 3) compared with the healthy non-pregnant women (Period 5) (P=0.02). The fractional proximal reabsorption of sodium (FPRNa+) at peak CCr was similar in the groups (NP: 0.74+/-0.01 HP: 0.78+/-0.02 and CG: 0.74+/-0.03, P=not significant (NS)) as was the distal delivery of sodium (DDNa+) (NP: 5.8+/-0.5; HP: 4.1+/-0.5 and CG: 4.3+/-0.4 meq/min, P=NS). Fractional excretion of urea (%) increased from 91.4+/-5.5 to 105.5+/-9.8%; 80.7+/-8.0 to 97.3+/-9.8; and 44.4+/-7.8 to 86.0+/-7.1 in NP, HP and CG, respectively (P=NS). There was a trend towards a poorer maternal and fetal outcome in the HP group. Mid-term borderline HP failed to increase CCr as much as NP did after a protein challenge, suggesting altered functional response of the nephron or lessened sensitivity of renal vasculature to additional vasodilator stimuli. These results support the interest of additional prospective studies with a larger number of patients to confirm these findings and evaluate the value of RR tests as predictors of outcome of pregnancies at risk.

Intravenous administration of amino acids during anesthesia stimulates muscle protein synthesis and heat accumulation in the body

The aim of this study was to determine the contribution of protein synthesis to the prevention of anesthesia-induced hypothermia by intravenous administration of an amino acid (AA) mixture. We examined changes in intraperitoneal temperature (Tcore), rates of protein synthesis (Ks) and the phosphorylation states of translation initiation regulators and their upstream signaling components in skeletal muscle of conscious (Nor) and propofol-anesthetized (Ane) rats after intravenous administration of a balanced AA mixture or saline (Sal). Compared with Sal administration, AA markedly attenuated the decrease in the Tcore of rats during anesthesia, while Tcore in the Nor-AA group became slightly elevated during treatment. Stimulation of muscle protein synthesis resulting from AA administration was observed in each case, but Ks in the Ane-AA group remained lower than in the Nor-Sal group. Administration of AA during anesthesia significantly increased plasma insulin to levels approximately 6-fold greater than the Nor-AA group and enhanced phosphorylation of 4E-BP1, S6K1, PKB and mTOR, relative to all other groups and treatments. These results suggest that AA administration during anesthesia stimulates muscle protein synthesis via insulin-mTOR–dependent activation of translation initiation regulators caused by markedly elevated insulin and thereby facilitates thermal accumulation in the body.

Intravenous administration of amino acids during anesthesia stimulates muscle protein synthesis and heat accumulation in the body

The present study was conducted to determine the contribution of muscle protein synthesis to the prevention of anesthesia-induced hypothermia by intravenous administration of an amino acid (AA) mixture. We examined the changes of intraperitoneal temperature (Tcore) and the rates of protein synthesis (K(s)) and the phosphorylation states of translation initiation regulators and their upstream signaling components in skeletal muscle in conscious (Nor) or propofol-anesthetized (Ane) rats after a 3-h intravenous administration of a balanced AA mixture or saline (Sal). Compared with Sal administration, the AA mixture administration markedly attenuated the decrease in Tcore in rats during anesthesia, whereas Tcore in the Nor-AA group became slightly elevated during treatment. Stimulation of muscle protein synthesis resulting from AA administration was observed in each case, although K(s) remained lower in the Ane-AA group than in the Nor-Sal group. AA administration during anesthesia significantly increased insulin concentrations to levels approximately 6-fold greater than in the Nor-AA group and enhanced phosphorylation of eukaryotic initiation factor 4E-binding protein-1 (4E-BP1) and ribosomal protein S6 protein kinase relative to all other groups and treatments. The alterations in the Ane-AA group were accompanied by hyperphosphorylation of protein kinase B and the mammalian target of rapamycin (mTOR). These results suggest that administration of an AA mixture during anesthesia stimulates muscle protein synthesis via insulin-mTOR-dependent activation of translation initiation regulators caused by markedly elevated insulin and, thereby, facilitates thermal accumulation in the body.

Pragmatic Approach to In-Hospital Nutrition in High-Risk Neonates

Extremely low birth weight infants may experience periods of moderate to severe undernutrition during the acute phase of their respiratory problems. This undernutrition contributes to early growth deficits in these patients and may have long-lasting effects, including poor neurodevelopmental outcome. Early postnatal intravenous amino-acid administration and early enteral feeding strategies will minimize the interruption of nutrient intake that occurs with premature birth. These two strategies will prevent intracellular energy failure, allow the administration of more non-protein energy, as well as enhance overall nutritional health, as evidenced by less postnatal weight loss and earlier return to birth weight, and improved overall postnatal growth and outcome.

Rapid intravenous administration of amino acids prevents biliary sludge induced by total parenteral nutrition in humans

The aim of this study was to evaluate whether daily rapid intravenous administration of amino acids (IVAA) prevented the formation of biliary sludge in humans receiving long-term total parenteral nutrition (TPN). Thirty adult patients receiving TPN for more than 28 consecutive days were studied. They were randomized to receive either saline solution (placebo) intravenously (15 patients) or 6.9% branched chain amino acid (BCAA)-enriched amino acid (15 synthetic amino acids; Freamine HBC) solution given by administration rapid intravenous (15 patients). The groups were similar with respect to age, sex, diagnosis, liver function test results, amylase levels, TPN time, and time of study. All patients underwent weekly ultrasound studies. Volume and emptying studies of the gallbladder in response to the study drug were performed after 1 week. As a result, none of the patients receiving rapid IVAA had sludge, whereas 11 of the 15 patients receiving placebo had sludge (P < 0.01). Results of emptying studies showed significant contraction of the gallbladder in those in the rapid IVAA group, but not in the placebo group. Consequently, the data suggest that rapid IVAA given daily prevents TPN-induced stasis and sludge in the gallbladder. We conclude that rapid IVAA should be used as routine prophylaxis against biliary sludge and formation of gallstones in patients receiving long-term TPN.

The effects of intravenous administration of amino acids and glucose on the milk production of dairy cows consuming diets based on grass silage

Two experiments, using intravenous infusion of nutrients, were carried out with the aim of separating milk production responses due to the provision of amino acids as precursors of milk protein synthesis from those due to the provision of amino acids as glucose precursors. Diets were based on grass silage of restricted fermentation and barley‐based supplements because it has been suggested that these diets might provide insufficient glucose precursors to meet the needs of lactose synthesis. The silages used in the experiments were of similar lactic acid contents [62 and 63 g kg–1 dry matter (DM)] but of different water‐soluble carbohydrate (WSC) contents (206 and 20 g kg–1 DM in Experiments 1 and 2 respectively). In Experiment 1, four dairy cows were given the following treatments in a 4 × 4 Latin square arrangement with periods of 10 d: (1) basal diet (Basal), (2) Basal plus jugular infusion of 182 g d–1 of amino acids simulating casein (TAA), (3) Basal plus 101 g d–1 of essential amino acids (EAA), being the essential amino acid component of the TAA treatment and (4) Basal plus 101 g d–1 of essential amino acids plus 50 g d–1 of glucose (EAA + G), being the glucose equivalent of the non‐essential amino acid component of treatment TAA. All infusions increased (P &lt; 0·05) the concentration of milk protein compared with Basal but only for TAA was the increase in the yield of milk protein statistically significant (P &lt; 0·05), amounting to 68 g d–1. Both TAA and EAA reduced (P &lt; 0·05) the concentration of milk fat. There was no difference between EAA and EAA + G treatments.In Experiment 2, five dairy cows were given the following treatments in a 5 × 5 Latin square design with periods of 7 d: (1) basal diet (Basal), (2) Basal plus 182 g d–1 of amino acids simulating casein (TAA), (3) Basal plus 182 g d–1 of non‐essential amino acids as in casein (NEAA), (4) Basal plus 100 g d–1 of glucose (G100) and (5) basal plus 230 g d–1 of glucose (G230). G100 supplied the glucose equivalent of NEAA whereas G230 supplied the caloric equivalent of NEAA. Again, only for TAA was the increase in yield of milk protein statistically significant (P &lt; 0·05), amounting to 83 g d–1. Neither glucose treatment caused any statistically significant (P &gt; 0·05) effect on the yield of milk protein nor the yield of milk lactose.It is concluded that, in both experiments, the primary nutritional limitation on milk protein output was the supply of amino acids as precursors of milk protein, there being no evidence to support a primary limitation due to glucose supply.

Issues in the Nutritional Support of the Ventilated Baby

Extremely low birth weight (ELBW) premature infants who populate intensive care nurseries today often receive such overriding attention to their acute respiratory illness that appropriate attention to certain other adjunctive needs; adequate nutrition is often delayed. The outcome for these ELBW infants may be influenced by the intensity and length of the period of less-than-adequate nutrition. This article discusses initial fluid therapy, early postnatal intravenous amino acid administration, choice of energy substrate, and initiation and advancement of enteral feedings.

Response of phenylalanine and leucine kinetics to branched chain- enriched amino acids and insulin in patients with cirrhosis

BACKGROUND & AIMS: We tested the effects of branched chain-enriched, aromatic-deficient amino acids with insulin to correct the altered protein turnover as well as phenylalanine (Phe) and leucine (Leu) rate of appearance in compensated cirrhotics and controls. METHODS: Phe and Leu tracers were infused both before and following intravenous amino acid administration with insulin and euglycemic clamp. RESULTS: In cirrhosis, fasting whole-body protein synthesis and protein degradation were normal; Phe rate of appearance was greater (P<0.05), whereas Leu rate of appearance/Phe rate of appearance ratio was approximately 35% less than in controls (P<0.001). Following the infusion, protein synthesis did not increase (+1% +/ 5% [NS] vs. +21% +/- 5% [P<0.05] in controls); protein degradation was more suppressed, whereas protein balance increased normally. Total Phe rate of appearance (0.91 +/- 0.13 micromol x kg-1 x min-1) and Leu/Phe disposal ratio (3.53 +/- 0.36) were nearly normalized (fasting controls, 0.68 +/- 0.07 micromol x kg-1 x min-1 and 2.87 +/- 0.14 micromol x kg-1 x min-1, respectively; P>0.05). However, Leu/Phe endogenous rate of appearance ration remained approximately 50% less (1.56 +/- 0.31 vs. 2.87 +/- 0.14; P<0.004) than in controls. CONCLUSIONS: Following this combined infusion in cirrhosis, net protein deposition increased normally despite a blunted response of protein synthesis. Phe and Leu to Phe peripheral disposal were near normalized; however, the exaggerated endogenous Phe production was not corrected entirely. (Gastroenterology 1996 Jul;111(1):127-37)

Dietary Supplementation of L-Arginine Ameliorates Renal Hypertrophy in Rats Fed a High-Protein Diet

Ingestion of a high-protein diet or intravenous administration of amino acids is associated with an increase in glomerular filtration rate (GFR). It can also lead to renal hypertrophy, and, if sustained, may cause glomerular sclerosis. L-Arginine administration ameliorates the progression of renal disease in rats with subtotal nephrectomy and prevents the increase in GFR observed in rats with experimental diabetes. The present study examines the potential effect(s) of L-arginine administration (1%) in the drinking water on the renal hypertrophy that occurs in rats fed a high-protein diet for 1 month. Four groups of female Sprague-Dawley rats, six in each group, were studied (95 +/- 1 g). Groups 1 and 2 were fed a low-protein diet (12% casein, 0.504% L-arginine); Group 1 was given tap water, whereas Group 2 was given tap water supplemented with L-arginine. Groups 3 and 4 were fed a high-protein diet (40% casein, 1.68% L-arginine); Group 3 was given tap water, whereas Group 4 was given tap water supplemented with L-arginine. The rats had free access to food and water during the study period. The kidney weight and the kidney to body weight ratio of rats of Group 3 were significantly greater than in the other groups of rats. Renal hypertrophy was prevented in the rats of Group 4. The excretion of orotic acid in the urine, an index of L-arginine deficiency, was significantly greater in rats of Group 3 than in rats of Group 4. Thus, the renal hypertrophy that occurs in rats fed a high-protein diet was decreased in rats given L-arginine supplementation in the drinking water. This effect was associated with less excretion of orotic acid in the urine in rats given L-arginine. A relative deficiency of L-arginine may occur during high-protein feeding that may shunt nitrogen metabolism from the urea cycle to the orotic acid pathway.

Hyperammonemic Encephalopathy due to Intravenous Amino Acid Administration in a Patient with Renal Insufficiency

Hyperammonemic Encephalopathy due to Intravenous Amino Acid Administration in a Patient with Renal Insufficiency

Increased energy expenditure after intravenous administration of amino acids.

Nutrient-induced thermogenesis (NIT) after parenteral administration of amino acids (AAs) was investigated in rats and compared with result obtained with intragastric administration. Resting energy expenditure was measured with a new type of open-circuit indirect calorimeter. The NIT increased shortly after parenteral AAs administration and reached a steady state in 30 minutes. The change in resting energy expenditure (the increment of resting energy expenditure over preinfusion baseline values) showed a significant relationship not only with the amount of infused AAs but also with the AA concentration in the portal vein. Furthermore, the increase in plasma AA concentrations in the portal vein was proportional to the amount of the particular AA infused. This relationship held true over the entire range tested. NIT with parenteral infusion (11% to 12%) was lower than that with intragastric infusion (20% to 23%). Plasma insulin, corticosterone, and glucagon levels increased after both parenteral and intragastric AAs administration, but the two methods did not show any significant differences in hormonal changes. The plasma aminogram of the portal vein after intragastric infusion was compared with that after parenteral infusion. Total plasma AA concentration and the levels of glutamine, lysine, arginine, glutamate, aspartate, and histidine were lower but the level of isoleucine was higher after intragastric infusion. On the basis of these results, it is believed that parenteral administration of AAs can induce thermogenesis, which may be regulated by the intraportal AA concentration. Considering the remarkable decrease in glutamine in the portal vein after intragastric infusion, the cost of intestinal metabolism may predominantly contribute to the NIT resulting from intragastric infusion.

Single-nephron responses to systemic administration of amino acids in dogs

It has been suggested that the tubuloglomerular feedback (TGF) system is responsible for renal vasodilation during systemic infusion of amino acid solutions. We evaluated the effect of intravenous administration of amino acids (serine, alanine, proline, and glycine; total dose of 0.075 mmol of amino acids.kg body wt-1.min-1) on whole kidney and single-nephron hemodynamics in pentobarbital sodium-anesthetized dogs. At spontaneous renal arterial pressure (RAP; 125.4 +/- 4.7 mmHg), measurements of single-nephron function obtained during tubular blockade, stop-flow pressure (SFP; 48.2 +/- 2.0 vs. 58.9 +/- 2.3 mmHg, P less than 0.01), and proximally determined single-nephron glomerular filtration rate (SNGFR-TPC; 73.9 +/- 7.0 vs. 93.4 +/- 7.6 nl/min, P less than 0.01) increased in parallel to the increases of outer cortical blood flow (OCBF; 15.4 +/- 1.1 vs. 19.1 +/- 1.5 units, P less than 0.05), renal blood flow (RBF; 4.60 +/- 0.18 vs. 5.73 +/- 0.22 ml.min-1.g kidney wt-1, P less than 0.01), and glomerular filtration rate (GFR; 0.885 +/- 0.034 vs. 1.116 +/- 0.034 ml.min-1.g kidney wt-1, P less than 0.01). Free-flow tubular fluid-to-plasma inulin ratios, determined from late proximal recollections during saline (control) and amino acid infusions failed to provide evidence for altered proximal reabsorption rate (1.63 +/- 0.12 vs. 1.58 +/- 0.17 during amino acids, NS). At reduced RAP (92.6 +/- 1.9 mmHg), where it is presumed that TGF-mediated vasodilation is already near maximal, the vasodilatory response to amino acid infusion was intact and single-nephron parameters measured during tubular blockade increased to the same extent as OCBF, RBF, and GFR.(ABSTRACT TRUNCATED AT 250 WORDS)