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Intravenous infusions of glucose stimulate key lipogenic enzymes in adipose tissue of dairy cows in a dose-dependent manner

The present study was investigated whether increasing amounts of glucose supply have a stimulatory effect on the mRNA abundance and activity of key lipogenic enzymes in adipose tissue of midlactation dairy cows. Twelve Holstein-Friesian dairy cows in midlactation were cannulated in the jugular vein and infused with either a 40% glucose solution (n=6) or saline (n=6). For glucose infusion cows, the infusion dose increased by 1.25%/d relative to the initial net energy for lactation (NEL) requirement until a maximum dose equating to a surplus of 30% NEL was reached on d 24. This maximum dose was maintained until d 28 and stopped thereafter (between d 29-32). Cows in the saline infusion group received an equivalent volume of 0.9% saline solution. Samples of subcutaneous adipose tissue were taken on d 0, 8, 16, 24, and 32 when surplus glucose reached 0, 10, 20, and 30% of the NEL requirement, respectively. The mRNA abundance of fatty acid synthase, cytoplasmic acetyl- coenzyme A synthetase, cytoplasmic glycerol 3-phosphate dehydrogenase-1, and glucose 6-phosphate dehydrogenase showed linear treatment × dose interactions with increasing mRNA abundance with increasing glucose dose. The increased mRNA abundance was paralleled by a linear treatment × dose interaction for fatty acid synthase and acetyl-coenzyme A synthetase enzymatic activities. The mRNA abundance of ATP-citrate lyase showed a tendency for linear treatment × dose interaction with increasing mRNA abundance with increasing glucose dose. The mRNA abundance of all tested enzymes, as well as the activities of fatty acid synthase and acetyl-coenzyme A synthetase, correlated with plasma glucose and serum insulin levels. In a multiple regression model, the predictive value of insulin was dominant over that of glucose. In conclusion, gradual increases in glucose supply upregulate key lipogenic enzymes in adipose tissue of midlactating dairy cows with linear dose dependency. Insulin appears to be critically involved in this regulation. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved

Külföldi játékszín

több tudósokkal kiadja BajzaElőbeszéd -- Galotti Emilia / németból Lessing után Kazinczy Ferenc -- Lessing -- A gyűrű : vígjáték / németből Schröder után Bajza -- Schröde

Dietary Sodium Intake and Sweat Sodium Losses in Endurance Athletes

Dietary Sodium Intake Compared to Sodium Losses in Endurance Athletes Context: Sweat rate and sodium concentration has been investigated previously for endurance athletes; however, dietary sodium intake has not been researched. Endurance athletes who have high sweat rates may need to supplement sodium in their diet in order to maintain fluid and sodium balance. Objective: To calculate daily sodium intake for cross country runners over three consecutive days of training and compare them to sweat sodium losses during the three training sessions. Design: Observational field study Participants: Ten athletes (age = 20.5 ± 1.51, height = 173.21 ± 12.66 cm, mass = 65.51 ± 10.60kg) participated. Interventions: Sweat rate was calculated by change in body weight adjusted for fluid consumed and length of training. Sterile sweat patches were used to collect sweat samples from the forearm and low back. The patches were removed post training session, placed in sterile tubes and centrifuged. Sweat was analyzed for sodium and chloride by ion-selective electrode. Diets were analyzed using a common nutrition analysis software, ESHA. Main Outcome Measurements: Sweat rate, sweat losses, sweat sodium and chloride concentrations, daily sodium and salt (NaCl) losses, daily dietary sodiumintake, calculated NaCl intake, and body mass. Results: On all experimental days, sodium intake exceeded sodiumloss. Calculated sweat rates displayed variability that ranged from 0.19 – 1.40 L·hr-1. Mean sweat sodium concentration was 60.44 ± 27.76 mmol/L−1 (3.71 ± 1.88 g) and ranged from 1.4-6.63 grams. Conclusion: Participant body weight remained consistent (day 1= 65.61 ± 10.48 kg, day 2= 65.51 ± 10.60 kg, day 3= 65.70 ± 10.48 kg). All runners’ dietary sodium intake was greater than measured sweat sodium losses indicating that they maintained sodium and fluid balance during these three days without the need for electrolyte replacement