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

The calculation of lateral stability with free controls

The discussion of the structural methods for obtaining lateral stability discloses the remarkable influence of the constant fuselage and wing proportions to the yawing moments. For the effectiveness of modifications in vertical tail surfaces and tail length, these quotas - little observed heretofore, in this connection - are decisive. This also applies to the amount of dihedral of the wing with regard to the roll stability of the complete wing already existing without angle of the dihedral

Supplemental data and calculations of the lateral stability of airplanes

In connection with the DVL Report 272 on the theory of the lateral stability of airplanes, the formal results are here amplified in some respects and their technical significance again briefly explained. Three numerical examples show how model tests for checking the lateral stability are to be evaluated and supplemented, if necessary, and how the stability limits depend on the design of the airplane and on the conditions of flight

Technical details in the structural development of Rohrbach seaplanes

The recent trial flights and acceptance tests of the Rohrbach "Romar," the largest seaplane in the world, have yielded results fully confirming the principles followed in its development. Its take-off weight of 19,000 kg, its beating the world record for raising the greatest useful load to 2000 m by almost 2500 kg and its remarkable showing in the seaworthiness tests are the results of intelligent researches, the guiding principles of which are briefly set forth in this article

Butyrate Permeation across the Isolated Ovine Reticulum Epithelium

We hypothesized that, due to the high pH of this compartment, the reticulum epithelium displays particular features in the transport of short-chain fatty acids (SCFA). Ovine reticulum epithelium was incubated in Ussing chambers using a bicarbonate-free buffer solution containing butyrate (20 mmol L−1). p-hydroxymercuribenzoic acid (pHMB), 5-(N-Ethyl-N-isopropyl)amiloride (EIPA), or ouabain were added to the buffer solution as inhibitors of monocarboxylate transporters, sodium-proton-exchangers, or the Na+/K+-ATPase, respectively. The short-circuit current (Isc) and transepithelial conductance (Gt) were monitored continuously while the flux rates of 14C-labelled butyrate were measured in the mucosal-to-serosal (Jmsbut) or serosal-to-mucosal direction (Jsmbut). Under control conditions, the mean values of Isc and Gt amounted to 2.54 ± 0.46 µEq cm−2 h−1 and 6.02 ± 3.3 mS cm−2, respectively. Jmsbut was 2.1 ± 1.01 µmol cm−2 h−1 on average and about twice as high as Jsmbut. Incubation with ouabain reduced Jmsbut, while Jsmbut was not affected. The serosal addition of EIPA did not affect Jmsbut but reduced Jsmbut by about 10%. The addition of pHMB to the mucosal or serosal solution reduced Jmsbut but had no effect on Jsmbut. Mucosally applied pHMB provoked a transient increase in the Isc. The serosal pHMB sharply reduced Isc. Our results demonstrate that butyrate can be effectively transported across the reticulum epithelium. The mechanisms involved in this absorption differ from those known from the rumen epithelium

Butyrate Protects Porcine Colon Epithelium from Hypoxia-Induced Damage on a Functional Level

The large intestinal epithelium is confronted with the necessity to adapt quickly to varying levels of oxygenation. In contrast to other tissues, it meets this requirement successfully and remains unharmed during (limited) hypoxic periods. The large intestine is also the site of bacterial fermentation producing short-chain fatty acids (SCFA). Amongst these SCFA, butyrate has been reported to ameliorate many pathological conditions. Thus, we hypothesized that butyrate protects the colonocytes from hypoxic damage. We used isolated porcine colon epithelium mounted in Ussing chambers, incubated it with or without butyrate and simulated hypoxia by changing the gassing regime to test this hypothesis. We found an increase in transepithelial conductance and a decrease in short-circuit current across the epithelia when simulating hypoxia for more than 30 min. Incubation with 50 mM butyrate significantly ameliorated these changes to the epithelial integrity. In order to characterize the protective mechanism, we compared the effects of butyrate to those of iso-butyrate and propionate. These two SCFAs exerted similar effects to butyrate. Therefore, we propose that the protective effect of butyrate on colon epithelium under hypoxia is not (only) based on its nutritive function, but rather on the intracellular signaling effects of SCFA