L.F. Medeiros

The special behavior of equine erythrocytes connected with the methemoglobin regulation

Erythrocytes from thoroughbred horses were submitted to total (80-90%) and partial (25-40%) oxidation of hemoglobin by sodium nitrite. The ability of these cells to reduce methemoglobin to hemoglobin in the presence of either glucose, glucose plus methylene blue or lactate was investigated. The results were compared with those ones obtained for human erythrocytes. Under total oxidation: the horse erythrocytes need longer incubation time with glucose or glucose plus methylene blue than human erythrocytes for reducing the methemoglobin; methylene blue did not enhance methemoglobin reduction in the equine erythrocytes, as occurred in human erythrocytes; for horses, lactate was a more efficient substrate in promoting methemoglobin reduction. The reduction of methemoglobin by equine erythrocytes under partial oxidation was very quick in any of the incubation media. The results can explain the incongruity between the previously reported inability of equine erythrocytes to reduce methemoglobin and the lack of methemoglobinemias in equine veterinary practice.

Glycolytic and hexosemonophosphate enzyme activities in the lantern muscles of the sea urchins, Arbacia lixula (Linn.), Echinometra lucunter (Linn.) and Lytechinus variegatus (Lamarck)

Abstract 1. 1. Activities of nine glycolytic and related enzymes were measured in lantern muscle extracts of the echinoids Arbacia lixula, Echinometra lucunter and Lytechinus variegatus . 2. 2. The specific activities of these enzymes were comparatively low, being often the highest in L. variegatus and the lowest in A. lixula . The major differences referred to HK, PGK and G-6-PDH activities. 3. 3. Noticeable differences in LDH activities were recorded in comparison with other invertebrate muscles. The implications of these results are discussed.

Effects of hexachlorophene on the metabolism of glucose and glutamate in rat brain.

Abstract 1. Rats were treated with a single i.p. dose (15 mg/kg) of hexachlorophene (HCP). 2. HCP decreased the activity of HK, PGK, LDH, and elicited a minor depression of GPI and PK. 3. A significant increase in PFK, GDH, Asp-T and Ala-T activities was observed after HCP. 4. An increase in brain glucose content was observed, whereas concentration of blood glucose remained unaltered.

Histometric study of age related changes in the thoracic aorta of Callus gallus (Linnaeus, 1758).

SummaryThe authors have studied the quantitative variations of elastic and collagenous fibers, muscle cells and cellular population in the mesarteria of the middle portion of the thoracic aorta of Gallus gallus from 1 day to 36 months of age. A histometric method has been employed, using an integrating eyepiece I (Zeiss Oberkochen) for the countings.The results obtained show that the concentration of elastic fibers increases from the first to the 30th day of age, decreasing from this point until 36 months while that of the collagenous fibers increases during the first and second period. The muscular tissue increases its concentration from the 30th day to 36th month, while the cellular population decreases from the 15th to 30th day, then remaining, stable until 36 months. From the variations pointed out here for the different elements studied between 30 days and 36 months of age, only those of the eollagenous fibers were linear with age.

Erythrocytes of thoroughbred horses in the after-birth hemolytic physiological process

Abstract 1. 1. The values of the erythrogram from the umbilical cord of newborn foals with 30–40 min (1 day), 3, 7, 30 days and adult thoroughbred horses were determined. 2. 2. Polycythemia was higher for umbilical cord than for one day animals. 3. 3. A physiological hemolysis took place just after birth, reaching its peak on the third day when a destruction of about 50% of erythrocytes occurred. 4. 4. The erythrocyte of thoroughbred horses is an excellent biological model for the studies of metabolical adaptations of the hemolytic physiological post-natal process.

Patterns of mid-to-term placental enzymes in rats treated with magnesium sulphate

1. Pregnant rats were injected daily with 150 mg/kg b.w. of magnesium sulphate (MgSO4) starting at the 5th day gestation and sacrificed at the 13th, 15th, 19th or the 21st day of pregnancy. 2. The profiles of LDH, G-6-PD, HK and Ala-T activities in mid-to-term placentae were not changed by the drug. 3. Placental PK was strongly activated by MgSO4 in 13-19 day pregnant rats, whereas Asp-T was more severely depressed at the final phase of pregnancy. 4. Although mild to moderate changes in the flow of substrates should be predictable by the results, it seems unlikely that these could account for the reported deleterious effects of MgSO4 on rat offsprings.

Inhibition of erythrocyte glycolysis associated with tranylcypromine (maoinhibitor) administration in rabbits: Pyruvate kinase deficiency

Abstract 1. 1. Rabbits were treated with two doses (40 mg/kg each dose) of tranylcypromine at 24 hr interval. 2. 2. Tranylcypromine affects the activity of GPI, PK, and LDH of red cells, whereas HK levels remain unaltered. 3. 3. The inhibition of PK activity was corrected in vitro by FDP.

Colostrum ingestion and age connected with physiological variations upon the electropherogram of newborn thoroughbred horses

Abstract 1. 1. The electropherogram of thoroughbred horses of different ages has been studied. 2. 2. The total protein and beta globulin increased over a period of 48 hr, while albumin increased over 24 hr. 3. 3. The amount of alpha globulin decreased over a period of 5 hr and then rose up to 24 hr. 4. 4. Gamma globulin was absent at birth and appeared after colostrum ingestion, rising over a period of 7 days.

Maternal and fetal liver enzymes of mid-to-term pregnant rats chronically treated with magnesium sulphate

1. Pregnant rats were injected daily with 150 mg/kg body weight magnesium sulphate (MgSO4) starting at the 5th day of gestation and sacrificed at the 13th, 15th, 19th or 21st day of pregnancy. 2. Maternal liver enzymes of glycolysis (HK, PFK, PK, LDH), pentose shunt pathway (G-6-PD) and glutamate metabolism (Ala-T, Asp-T) were unaltered by the treatment. 3. Fetal liver PK, LDH, G-6-PD, Ala-T and Asp-T activities were strongly activated by MgSO4 to levels in some instances as high or even higher than those found in the adult rat liver. 4. Results support recent evidence that MgSO4 induces precocious maturation of certain morphofunctional features of the fetal rat liver. 5. Data presented herein cannot account for the strong deleterious effects of the drug on rat pregnancy. Instead, such effects would be better explained by the direct cell toxicity of MgSO4.

Glycolytic intermediates and glutathione levels of erythrocyte: Comparisons between erythrocytes of humans and thoroughbred horses

Abstract 1. 1. 2,3-DPG, ATP, ADP, AMP and GSH content of red cells of horses are compared with the levels in human red blood cells. 2. 2. Horses showed lower values for these intermediates in terms of numbers of erythrocytes. 3. 3. If the values are considered in terms of MCV and MCH, the amount of 2,3 DPG and GSH from horses are more than those from human cells whilst the adenosine phosphates remain at lower values.