Effect of ethyl acetate on the transport of sodium and glucose in the hamster small intestine in vitro

5 Final Report on the Safety Assessment of Ethyl Acetate and Butyl Acetate

Ethyl and Butyl Acetate are used as solvents in nail polish, nail polish removers, basecoats, and other manicuring preparations.

Ethyl and Butyl Acetate were relatively nontoxic when administered orally, dermally, or by inhalation to rabbits, rats, mice, and guinea pigs. A nail polish containing 10% Ethyl Acetate and 25% Butyl Acetate was a moderate to severe irritant in unrinsed rabbit eyes and a mild irritant in rinsed rabbit eyes. Butyl Acetate was not a sensitizer in either mice or guinea pigs.

Ethyl and Butyl Acetate were nonmutagenic when tested by the Ames procedure, Rec-assay, and micronucleus assay. Neither compound induces mitotic aneuploidy in yeast or chromosomal aberrations in Chinese hamster fibroblasts. Butyl Acetate was not teratogenic when inhaled.

Ethyl Acetate and Butyl Acetate were mild skin irritants but not sensitizers to humans. Ethyl Acetate was neither phototoxic or photoallergenic in human tests.

It is concluded that Ethyl Acetate and Butyl Acetate are safe as cosmetic ingredients in the present practices of use and concentration.

Effect of Milk Allowance on Concentrate Intake, Ruminal Environment, and Ruminal Development in Milk-Fed Holstein Calves

The aim of the present experiment was to test the hypothesis that a barley-based concentrate would induce an acidic ruminal environment in young calves and that increased milk allowance would alleviate this condition. Eight Holstein calves ruminally cannulated at d 7 +/- 1 of age were used to study the effect of variation in barley-based starter concentrate intake induced by 4 different milk allowances (3.10, 4.84, 6.60, and 8.34 kg of milk replacer/d; 123 g of dry matter/kg of milk) on the ruminal environment, blood variables, and fore-stomach development from wk 2 to 5 of age. Twelve ruminal fluid samples were collected during a weekly 24-h sampling in 4 consecutive weeks. Blood samples were collected by venipuncture between 1200 and 1300 h on ruminal sampling days. Rumen papillae development and visceral organ mass were recorded at slaughter. A linear treatment x week effect was observed for concentrate intake, with the calves fed the lowest milk allowance having the fastest increase in concentrate intake whereby these calves reached the same ME intake in wk 5 compared with calves with the highest milk allowance. Effects on ruminal variables were dominated by week of sampling, with minor differences among treatments. Ruminal pH was below 5.5 for 5 to 13 h/d and all calves with concentrate intake above 20 g of dry matter/d were observed to have a daily ruminal pH minimum at pH 5.5 or lower. The ruminal concentration of total volatile fatty acids (VFA) increased from 71 to 133 +/- 9 mmol/L in wk 2 to 5 and was characterized by a relatively high molar proportion of propionate, increasing from 34 to 40 mol/100 mol of VFA in wk 2 to 5. In addition, the presence of ethanol and propanol as well as numerous VFA esters points to a ruminal environment with a relatively high hydrogen pressure. Plasma glucose and insulin responded to the highest milk allowance in wk 2 to 4. Plasma VFA and ketone bodies increased with the lowest milk allowance in wk 4 to 5. At slaughter, empty wet weights of the rumen + reticulum and omasum as well as mass of digesta in these compartments were found to decrease linearly and perirenal fat was found to increase linearly with milk allowance, indicating that the milk allowance changed the body composition of the calves. Lengths of ruminal papillae in the atrium and ventral ruminal sac were not affected by treatment. We concluded that the ruminal environment of young calves fed a barley-based starter concentrate was characterized by a low ruminal pH and high VFA concentration regardless of the milk allowance.

In vivo and in vitro sugar transport in frog intestine

In the frog intestine, both in vitro and in vivo, experiments were carried out in order to increase knowledge of the mechanism of sugar exit across the basolateral membrane of the enterocyte. The frog intestine was chosen because it lacks crypt cells and, consequently, any external fluid circuit mechanism during sugar transport can be avoided. Therefore, the sugar concentration in the absorbate collected on the serosal side is likely to be similar to that present underneath the basolateral membrane of the enterocyte. Under this condition, cell and absorbate sugar concentrations are similar; yet there is a concomitant net transintestinal sugar transport. Moreover, in in vivo experiments a net transintestinal sugar transport takes place even against a concentration difference. These results suggest that sugar exit across the basolateral membrane is not simply due to a chemically facilitated diffusion.

d-Glucose balance in the enterocyte of rat jejunum "in vitro"

An everted sac of male albino rat jejunum (Wistar strain) incubated "in vitro" in used. Net d-glucose and Na+ transport together with d-glucose concentration in the emerging fluid [5], or in ths serosal fluid, and in the enterocytes are determined. Cell d-glucose concentration does not change significantly in a range between 20-200 mumoles or between 50-500 mumoles of net d-glucose transepithelial transport, depending on the experimental conditions. As far as cellular d-glucose and Na+ concentration is concerned, the enterocyte behaves as an homeostatic system. The mechanism involved in d-glucose extrusion is extensively discussed. Two hypothesis seem to be possible. First, the mechanism is an active metabolically dependent one, just as it is for sodium transport. Second, the metabolic activity favours d-glucose facilitated permeability through the basolateral membrane in such a way as to maintain a constant relationship between d-glucose and Na-extrusion, notwithstanding the fact that d-glucose concentration gradient across the basolateral membrane lowers by increasing Na and glucose extrusion rate.

Hyperglycemia and net transintestinal glucose and sodium transport in the rat

Hyperglycemia produced by intravenous infusion of glucose cause, in the everted jejunum of rat, an increase of net transintestinal transport of glucose, Na and water without modifying their cell concentration. The concentration of glucose in the fluid pouring out at the serosal side is higher than the calculated intracellular concentration, especially in the experiments in which the serosal compartment is initially empty. This fact could be explained by the possible existence of an active extrusion mechanism in the basolateral membrane of the enterocyte.

Tubular extrusion of D-glucose in the isolated rabbit kidney perfused in vitro

The extrusion mechanism of d-glucose by tubular cells was investigated in isolated rabbit kidneys perfused with normal or hyperglicemic blood, added with 14C-inulin, by relating the values of the ratio between the intracellular and extracellular glucose concentration (Gi/Ge) in the cortical tissue to the respective plasma concentration Gp (= Ge). The apparent extracellular space was calculated in each experiment from the kinetics of the 14C-inulin efflux from cortical slices excised at the end of the perfusion period (mean value = 20.7 +/- 1.7 of the total vol.). The total intra and extracellular amount of glucose was measured in two contiguous slices excised from the cortex. The total water was expressed by the difference between the fresh and dry weight of the slice, the intracellular water by the difference between the total and extracellular water. From these volumes the respective apparent glucose concentrations could be found. The Gi/Ge values tend to 1, that is to a uniform intra and extracellular distribution of glucose, only at high plasma glucose levels. These results do not seem to be in agreement with a D-glucose transfer from the cell to the subepithelial spaces down a concentration gradient.

The calculated glucose concentration profile in the intercellular spaces of everted jejunum of rat

On the basis of experimental data from isolated and everted rat jejunum and on extension of Diamond and Bossert's mathematical model, the glucose concentration in the intercellular spaces has been calculated and has been found higher (less than 2 mM) than that present in the serosal space.

Water absorption and swelling in the rat small intestine in vitro

Net mucosal-to-serosal water transport and water retention within the tissue were simultaneously measured in the isolated, everted rat jejunum and ileum along with time. The swelling of the epithelium (delta w/DW-delta w/DW-delta v/DW) precedes the absorption of fluid and then it remains contant throughout the experiment. The water uptake, determined as a weight increase, (delta w/DW) and the net water transport determined as a serosal volume increase (delta v/DW) were higher in Krebs-Ringer-bicarbonate than in a Krebs-Ringer-phosphate medium. In the jejunum glucose markedly stimulated both the tissue retention and net transport of water, but such effect was not seen in the ileum. Replacement of chloride with sulphate in the medium diminishes both water transport and retention, but both were markedly stimulated by the addition of glucose to such medium. As a conclusion it seems that during water transport the epithelial layer swells and the swelling increases when the amount of water transported is increased.

Effects of serosally added sugars on the transepithelial electrical properties of the perfused goldfish intestine

1. A study has been made of the effect of serosally added sugars on the transmural potential difference and electrical resistance of the perfused goldfish intestine. 2. Addition of glucose at the serosal side resulted in a decrease of the transmural potential difference independent of the presence or absence of glucose at the mucosal side. The transepithelial resistance did not change. 3. The serosal glucose effect persisted in the presence of phlorizin at the mucosal side. 4. With the activity transported non-metabolized glucose analogue 3-oxy-methylglucose the same effects were observed as with glucose. 5. Replacement of NaCl by cholineCl, RbCl or LiCl at both sides of the intestine had a diminishing effect on the glucose evoked potentials and on the transepithelial conductance. 6. Phlorizin in concentrations lower than 10(-4) M, at the serosal side did not influence neither the mucosal nor the serosal glucose effects. 7. Ouabain at the serosal side inhibited the serosal glucose effect and decreased the transepithelial conductance. 8. The results support the concept that sugar transport at the serosal side of the epithelial cell has features in common with the sodium-dependent sugar transport mechanism at the mucosal side.