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PubMed1999

Determination of the maximum steady state of lactate (MLSS) in saliva: an alternative to blood lactate determination.

Based on previous research which shows parallelism between the saliva and blood lactate response during incremental exercise, we hypothesized that a "maximum salivary lactate steady state" (saliva-MLSS) might exist. Thus, the aim of the present investigation was to establish 1) which lower limit for the increase in salivary lactate concentration during a constant workload (i.e., from the 10th to the 20th min) test could be used to determine the saliva-MLSS and 2) if the exercise intensity corresponding to the saliva-MLSS is identical to that evoking the (blood) MLSS. Twelve male amateur athletes of mean ( +/- SD) age 24 +/- 5 year were selected for the study. Based on the results of a previous maximal cycle ergometer test for lactate threshold (LT) determination, each subject performed consecutive constant workload tests of 20-min duration on separate days for MLSS determination. Blood and saliva (25 microl) samples were collected at 0, 10, and 20 min during the tests for lactate determination. A Student's t-test for paired data demonstrated that a salivary lactate increase of 0.8 mM corresponded to the saliva-MLSS. At this value, indeed, no significant differences were observed between the mean V(.)O(2) and W values corresponding to the MLSS and the saliva-MLSS. In conclusion, the present findings indicate that 0.8 mM is the lower limit for the increase in saliva lactate concentration during a constant load test and thus is that which might be used as a reference to determine saliva-MLSS. Furthermore, saliva-MLSS might be used as an alternative to MLSS determination in blood samples.

Adult↗
PubMed1993

Effect of epidermal growth factor/transforming growth factor alpha on lactate production in porcine Sertoli cells: glucose transport and lactate dehydrogenase isozymes as potential sites of action.

Germ cell development is dependent upon the delivery of essential nutriments such as lactate originating from Sertoli cells. Lactate production is under the systemic control but probably also under a local control exerted via certain growth factors. By using a model of porcine cultured Sertoli cells, we have characterized the action of epidermal growth factor (EGF) on lactate production and further delineated the potential biochemical mechanisms involved in the EGF action. EGF stimulated lactate production in a time and dose dependent manner with a half-maximal (ED50) and maximal effects, respectively with 3.8 (0.6 x 10(-9) M) and 22 ng/ml of EGF. Lactate formation involves several biochemical steps among which the glucose substrate uptake and transport system as well as the lactate dehydrogenase (LDH) activity appear to play key roles. We report here that EGF increased the uptake of glucose evaluated through that of 2-deoxy-D-glucose (2-DOG), a non-metabolizable glucose analog. Such an increase in glucose substrate uptake occurs both after a long term (48 h) and a short term treatment (ED50 = 6.4 ng/ml, 1.1 x 10(-9) M EGF). Moreover, EGF was also able to enhance the activity of the Sertoli cell LDH. The maximal effect of the growth factor on LDH activity was observed after a long term (24 h) treatment with an ED50 of 7 ng/ml (1.2 x 10(-9) M).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Specific changes in lactate levels, lactate dehydrogenase patterns and cytochrome b559 in Dictyostelium discoideum caused by queuine.

Higher eukaryotes contain tRNA transglycosylases that incorporate the guanine derivative queuine from the nutritional environment into specific tRNAs by exchange with guanine at position 34. Alterations in the queuosine content of specific tRNAs are suggested to be involved in regulatory mechanisms of major routes of metabolism during differentiation. Dictyostelium discoideum has been applied as a model to investigate the function of queuine or queuine-containing tRNAs. Axenic strains are supplied with queuine by peptone, but they grow equally well in a defined queuine-free medium. Queuine-lacking amoebae, starved in suspension culture for 24 h, lose their ability to differentiate into stalk cells and spores, whereas amoebae sufficiently supplied with queuine will overcome this metabolic stress and undergo further development when plated on agar. The results presented here show that D(-)-lactate occurs in the slime mould in millimolar amounts and that its level is remarkably decreased in queuine-lacking cells after 24 h of starvation in suspension culture. On isoelectric-focusing polyacrylamide gels, nine different forms of NAD-dependent D(-)-lactate dehydrogenase can be separated from extracts of vegetative cells, and six forms from extracts of the starved cells. Under queuine limitation, one form is missing in the starved cells. Low amounts of L(+)-lactate are usually found in vegetative amoebae but significantly less in queuine-lacking cells. Five forms of NAD-dependent L(+)-lactate dehydrogenase are detectable in extracts from vegetative, queuine-treated cells, and slight alterations occur in queuine-deficient amoebae. In the starved cells only one form of L(+)-lactate dehydrogenase is found, irrespective of the supply of queuine to the cells. A cytochrome of type b with an absorption maximum at 559 nm accumulates during starvation only in queuine-lacking cells; it might be a component of an NAD-independent lactic acid oxidoreductase as is cytochrome b 557 in yeast and be responsible for the reduced level of lactate in cells lacking queuine in tRNA.

Cytochrome b Group↗
PubMed2002

Regulation of lactate production and glucose transport as well as of glucose transporter 1 and lactate dehydrogenase A mRNA levels by basic fibroblast growth factor in rat Sertoli cells.

By using cultured rat Sertoli cells as a model, both the action of basic fibroblast growth factor (bFGF) on lactate production and the site of this action were studied. bFGF stimulated Sertoli cell lactate production in a dose-dependent manner (basal: 7.3+/-0.5; 0.1 ng/ml bFGF: 7.5+/-0.5; 1 ng/ml bFGF: 7.5+/-0.6; 10 ng/ml bFGF: 10.3+/-1.0; 30 ng/ml bFGF: 15.2+/-1.5; 50 ng/ml bFGF: 15.4+/-1.6 microg/microg DNA). Two major sites for the action of this growth factor were identified. First, bFGF was shown to exert short- and long-term stimulatory effects on glucose transport (basal: 1170+/-102; 30 ng/ml bFGF for 120 min: 1718+/-152 and basal: 718+/-64; 30 ng/ml bFGF for 48 h: 1069+/-69 d.p.m./microg DNA respectively). Short-term bFGF stimulation of glucose transport was not inhibited by the protein synthesis inhibitor cycloheximide. These results indicate that short-term bFGF stimulation of glucose uptake does not involve an increase in the number of glucose transporters. On the other hand, stimulation with bFGF for periods of time longer than 12 h increased glucose transporter 1 (GLUT1) mRNA levels. These increased mRNA levels were probably ultimately responsible for the increments in glucose uptake that are observed in long-term treated cultures. Secondly, bFGF increased lactate dehydrogenase (LDH) activity (basal: 31.0+/-1.4; 30 ng/ml bFGF: 45.7+/- 2.4 mIU/microg DNA). The principal subunit component of those LDH isozymes that favors the transformation of pyruvate to lactate is subunit A. bFGF increased LDH A mRNA levels in a dose- and time-dependent manner. In summary, the results presented herein show that glucose transport, LDH activity and GLUT1 and LDH A mRNA levels are regulated by bFGF to achieve an increase in lactate production. These observed regulatory actions provide unequivocal evidence of the participation of bFGF in Sertoli cell lactate production which may be related to normal germ cell development.

Animals↗
PubMed1988

Net portal absorption of volatile fatty acids and L(+)-lactate by lactating Holstein cows.

Net absorption of L-lactate and VFA from the portal drained viscera of first lactation Holstein cows was measured at 4, 8, (four cows), 12, 16, and 20 wk (two cows) of lactation. Chronic indwelling catheters were installed 7 to 14 d postpartum in appropriate vessels to measure blood flow and net nutrient absorption. Cows were fed a completely mixed, 60:40 (dry basis) corn silage:supplement diet and milked every 12 h. Average metabolizable energy intake was 2.8X maintenance and mean milk production was 24.0 kg. Net absorption of lactate, any of the VFA, or their total was not affected by week postpartum. Net absorption of L-lactate, VFA, and alpha-amino N accounted in sum for 53.6% of metabolizable energy intake; contributions of each component to energy in absorbed nutrients were acetate and propionate, 29.5% each; alpha-amino N, 23.4%; L-lactate, 5.4%; n-butyrate, 5.3%; 2-methylbutyrate, 2.8%, and i-butyrate, i-valerate, and n-valerate, 1.2 to 1.6% each. Comparison of paired samples of blood and plasma showed that blood cells contribute to the transport of acetate, propionate, i-butyrate, and 2-methyl-butyrate but not of n-butyrate, i-valerate, or n-valerate.

Animals↗
PubMed1975

Lactate dehydrogenase isozymes of salmonid fish. Evidence for unique and rapid functional divergence of duplicated H-4 lactate dehydrogenases.

Salmonid fish, as a result of total genome duplication, have two genes, Ldh H and Ldh H', coding for polypeptides H and H', respectively, both of which have been shown in their tetrameric forms to be immunologically related to the classical H-4 lactate dehydrogenase isozyme of higher vertebrates (Bailey, G. S., and Wilson, A. C. (1968) J. Biol. Chem. 243,5843). The H-4 and H'-4 isozymes have now been highly purified from quinnat salmon, and their chemical, physical, immunological, and catalytic properties examined, and compared to the M-4 isozyme of salmon. The two proteins H-4 and H'-4 are shown to be very similar in amino acid composition, but significant differences in a few residues suggest differences in amino acid sequences. This suggestion was born out by quantitative immunological experiments in which the H-4 and H'-4 isozymes were shown to be about as different from each other as are the H-4 lactate dehydrogenases of chicken and duck. This suggests that the gene duplication event in salmon which give rise to two Ldh H genes occurred approximately 80 to 100 million years ago. The H'-4 lactate dehydrogenase which has risen from this duplication in salmon is shown to be somewhat intermediate between H-4 and M-4 in thermal stability, and in all catalytic properties examined, including substrate optima, Michaelis constants, and susceptibility to inhibition by high levels of substrate. In particular the H'-4 isozyme is almost exactly intermediate between H-4 and M-4 in its resistance to product inhibition by lactate, the catalytic parameter suggested to be of major functional importance to M-4 lactate dehydrogenase isozymes (Stambaugh, R., and Post D. (1966) J. Biol. Chem. 241,1462). Further, tissue distribution of these isozymes in salmon and trout are shown to be unusual. The M-4 isozyme salmon and trout are shown to be unusual. The M-4 isozyme occurs in very few tissues in detectable levels. It is the H-4 and H'-4 rather than H-4 and M-4, which occur in independently variable but significant levels in most tissues examined. Thus the H'-4 isozyme, despite its very close structural similarity to H-4 appears to possess functional properties which are different from either H-4 or M-4 in salmon, and some properties are midway between the two. This finding, together with the unusual tissue distribution of these isozymes, suggests that salmon with H'-4 lactate dehydrogenase is evolving to function catalytically in the absence of a balanced H-4-M-4 isozyme complement in most tissues. This balance seems to be met in most tissues by combinations of H-4 and H'-4,

Amino Acids↗
PubMed1981

Early (chemical) diagnosis of bacterial meningitis--cerebrospinal fluid glucose, lactate, and lactate dehydrogenase compared.

Both lactate and lactate dehydrogenase are more sensitive as early indicators of bacterial meningitis than is glucose, and both appear to help differentiate aseptic from bacterial meningitis. In selected cases, lactate dehydrogenase may be more sensitive than lactate. We also give reference intervals for cerebrospinal fluid cell count, glucose, lactate, and lactate dehydrogenase.

Child↗
PubMed1976

Spectrophotometric and electrochemical determinations of L(+)-lactate in blood by use of lactate dehydrogenase from yeast.

Lactate can be determined rapidly in blood by spectrophotometric and amperometric (enzyme electrode) procedures based on its oxidation by ferricyanide, the reaction being catalyzed with yeast L(+)-lactate dehydrogenase (cytochrome b2) (EC 1.1.2.3). In the photometric method lactate can be measured in a few minutes, but blood samples must first be deproteinized. In the amperometric procedure no treatment of blood is needed except ferricyanide addition. The enzyme electrode we used has a response time shorter than 1 min when its critical variables are optimized. Preliminary standardization is reduced to minimum operation, because electrode response is proportional to lactate concentration over a wide range (0.1 to 8.0 mol/liter) and many determinations can be done with little cost in enzyme. A simple electrical device ("two-electrode device") is described that is well suited for furture micro-cell construction. Lactate determinations on a series of normal blood samples show no deviation between results by these new methods and the usual ultraviolet spectrophotometric lactate tests.

Animals↗
PubMed1995

Placental and lactational transfer of lead in rats: a study on the lactational process and effects on offspring.

The effects of placental and lactational exposure to lead (Pb) were studied in suckling rats after long-term exposure of their dams to Pb in drinking water. Dams were given 12 mM Pb-acetate in the drinking water 8 weeks prior to mating and during gestation. One group of dams was also continuously exposed during lactation until day 15. Neonates from Pb-treated dams were cross-fostered at birth to control dams treated with Na-acetate (12 mM) in the drinking water. In the same way, neonates from dams receiving control water were in the same way cross-fostered to Pb-exposed dams. All animals were killed at day 15 of lactation, when measurements were performed. Continuous Pb exposure during gestation and lactation resulted in milk Pb levels approximately 2.5 times higher than the blood Pb levels. When Pb exposure was terminated at parturition the milk Pb levels were at a level similar to those of blood Pb at day 15 of lactation, and only 10% of the milk levels found after continuous Pb exposure. Exposure to Pb via placenta and milk in offspring from dams exposed continuously resulted in more than 6 times higher blood and brain Pb levels than in offspring exposed only via the placenta. Exposure only via milk in offspring from dams exposed to Pb until parturition resulted in higher blood Pb levels than in offspring exposed to Pb only via the placenta. This indicates that the lactational transfer after current or recent exposure of Pb in dams is considerably higher than placental transfer. Offspring in all the exposed groups had decreased ALAD activity in the blood. An exponential relationship between blood Pb levels and ALAD activity was demonstrated in the offspring. Due to the exponential decrease in ALAD activity at increasing blood Pb levels, ALAD is particularly sensitive in reflecting differences in Pb exposure within the lowest range of blood Pb levels. There was a slight effect on weight gain in the offspring. However, there was no effect on milk quality, as measure by milk lipid, protein and calcium concentrations, nor on milk production assessed by the mammary gland RNA and DNA content. This indicates that the effect on weight gain was a direct effect of Pb in the offspring.

Animals↗
PubMed1992

Effects of immobilization stress on tuberoinfundibular dopaminergic (TIDA) neuronal activity and prolactin levels in lactating and non-lactating female rats.

The effects of immobilization stress on the prolactin secretory response and on the activity of the tuberoinfundibular dopaminergic (TIDA) neurons were determined in intact, virgin female rats on the morning of diestrus or proestrus and in post-partum, lactating female rats. The virgin females exhibited a significant increase in circulating levels of prolactin which was evident by 1 minute and persisted during the immobilization (5 minutes). In contrast, the prolactin secretory response in lactating females was significantly attenuated compared to non-lactating animals. The activity of the TIDA neurons was not altered by the 5 minutes of stress. Even after 30 minutes of immobilization, TIDA neuronal activity was not affected in either the lactating or cycling females. These data suggest that the cycling female rat is capable of a prolactin secretory response to the stressor without inhibition of TIDA neuronal activity. It seems likely that prolactin releasing factors mediate this response. In contrast, stress did not produce a similar prolactin increase during lactation. It seems likely that, during lactation, the pituitary is not sensitive to releasing factors unless the TIDA neurons are inhibited. There appear to be differences in the sensitivity of the pituitary depending on the physiological state of the model employed.

Animals↗
PubMed1994

Effects of dehydration, rehydration, and hyperhydration in the lactating and non-lactating black Moroccan goat.

The effects of water deprivation, rehydration and hyperhydration were investigated in the black Moroccan goat (Capra hircus). Mean daily water intake was 46 +/- 5 ml/kg in lactating and 36 +/- 4 ml/kg in non-lactating black Moroccan goats, and milk production 21 +/- 1 ml/kg. Mean urine excretion was 8 +/- 2 ml/kg body weight in both groups, and the daily water losses via evaporation and feces were estimated at 23 +/- 3 ml/kg during lactation and 28 +/- 4 ml/kg during non-lactation. Forty-eight hours of water deprivation caused a body weight loss of 9% and 6% in lactating and non-lactating goats, respectively, and a drop of 28% in milk production with only a slight decrease in food intake. After rehydration, the elevated plasma osmolality as well as Na and total protein concentrations returned to basal values within 2-3 hr, indicating a rapid absorption of the ingested water, but urine excretion did not increase. After hyperhydration (10% of body weight), 46% of the load was excreted by the kidneys within 6 hr. In conclusion, black Moroccan goats have a low water turnover, and they can retain water upon rehydration but not store excess water after hyperhydration.

Aldosterone↗
PubMed2004

The importance of farrowing to service interval in sows served during lactation or after shorter lactation than 28 days.

In a retrospective study, based on data from the national litter recording system, farrowing rate and litter size of sows served (inseminated or mated) during the lactation period (n = 574) or after a lactation period shorter than 28 days (n = 14,219) were analysed. The results were compared with the corresponding figures for sows with lactation length between 28 and 35 days and weaning to first service interval of 4 or 5 days (reference group; n = 41,741). The farrowing rate of the reference group was 80.9% and subsequent litter size was 13.7 total piglets born. Among sows served prior to weaning, the farrowing rates and litter sizes were significantly lower for those served earlier than 22 days post-farrowing compared to those served later (P < 0.05). Shorter lactations than 28 days and service within 10 days post-weaning led to lower farrowing rates than in the reference group (P < 0.01). Significant differences were seen after different lactation lengths. After correction for weaning to service interval, preceding litter size weaned, parity, breed and the interaction between parity and breed, litter size was significantly and positively associated with the preceding lactation length. The study shows that service within the first 3 weeks post-farrowing results in reduced reproductive performance.

Animals↗
PubMed2000

Menstrual patterns and fecundity among non-lactating and lactating cycling women in rural highland Bolivia: implications for contraceptive choice.

Choosing an appropriate contraceptive method, particularly one based on fertility awareness, depends in part upon the degree of a woman's cycling regularity. However, while the suppressive effect of lactation on ovarian function is well established, the potential influence of continued breastfeeding on menstrual patterns once post-partum cycling has resumed is largely unexamined. This longitudinal study in a population of non-contracepting Aymara women (n = 191 providing 665 non-truncated menstrual segments) identified conceptions and fetal loss via urine tests for hCG and classified segments accordingly to test the hypotheses that (1) cycles in lactating women are significantly different in length and regularity from those of non-lactating women, and (2) cycles in women living at high altitude are significantly different in length and regularity from those at lower altitudes. Analyses found that segments are significantly longer and regularity tends to be less common among lactating than non-lactating women; however, the rate of conception is twice as great among the former than the latter, and the distribution of conception outcomes does not differ between the two groups. Menstrual regularity is not the norm in this population, even among those who are not currently breastfeeding. High altitude per se does not appear to influence menstrual cycling as both regularity and segment length are comparable to other populations, hence women indigenous to high altitude are suitable candidates for a wide variety of contraceptive choices. In addition, these findings suggest that studies of fecundability limited to non-lactating women may be biased towards those of relatively lower fecundity.

Bolivia↗
PubMed1978

Effects of ammonia and norvaline on lactate metabolism by hepatocytes from starved rats. The use of 14C-labelled lactate in studies of hepatic gluconeogenesis.

1. Hepatocytes from starved rats were incubated with l-lactate and NH(4)Cl or norvaline, and the rates of the tricarboxylic acid cycle and of gluconeogenesis were calculated from changes in metabolite concentrations or from radioisotopic data from incubations with labelled lactate or propionate. 2. Gluconeogenesis was stimulated by the addition of 10mm-NH(4)Cl, 5mm-norvaline or 1mm-oleate by 27, 45 and 59% respectively. NH(4)Cl or norvaline also increased lactate uptake. Norvaline inhibited urea synthesis from NH(4)Cl by 85%. 3. The effects of NH(4)Cl and norvaline were not additive. However, NH(4)Cl inhibited and norvaline was without effect on gluconeogenesis from pyruvate, indicating that the two compounds act by different mechanisms. 4. The tricarboxylic acid-cycle flux was increased 80% by lactate, and NH(4)Cl caused a further 25% stimulation. Norvaline had no effect on the tricarboxylic acid-cycle flux. NH(4)Cl and norvaline tripled and doubled, respectively, flux through pyruvate dehydrogenase. 5. Total ATP formation was calculated to range from 470 to 830mumol/h per 100mg of protein, of which the basic metabolic activity accounted for 400-450mumol/h per 100mg of protein. ATP formation does not seem to be rate-limiting for gluconeogenesis. 6. Pyruvate recycling was estimated from the (14)C yield from [1-(14)C]propionate in lactate and glucose to be 10-30% of the flux of phosphoenolpyruvate to glucose. The further addition of NH(4)Cl more than doubled the recycling of pyruvate. 7. [1,4-(14)C]Succinate was rapidly metabolized by hepatocytes. About 20% of the radioactivity was recovered in glucose, indicating that succinate is also metabolized by intact (non-damaged) hepatocytes. 8. It is concluded that the metabolism of lactate by the liver is too complex to allow simple rate measurements with labelled compounds.

Adenosine Triphosphate↗
PubMed1986

Energy and nitrogen metabolism of rabbits during pregnancy, lactation, and concurrent pregnancy and lactation.

1. In an experiment twenty-four cross-bred does were used, six in each of four physiological states: non-pregnant (NP), pregnant (P), lactating (L) or concurrently pregnant and lactating (CPL). They were offered a diet of high nutrient density (crude protein (nitrogen x 6.25) 272 g/kg dry matter (DM), metabolizable energy 15.5 MJ/kg DM) at one of two intakes on a scale based on metabolic body-weight (kg body-weight 0.75). The study lasted for 24 d and was divided into three consecutive 8 d periods: 'early', 'mid-' and 'late' pregnancy or lactation, or concurrent pregnancy and lactation. 2. Around the mid-point of each period the does were placed for 24 h in a gradient-layer calorimeter, and measurements of energy exchange were made. N balance was also measured throughout each period of the study. 3. Milk output in L and CPL does was measured by weighing the does immediately before and after suckling once each day. Milk samples were taken from a parallel group of does and the estimates of milk composition applied to the experimental group. 4. Milk yields and composition were similar for L and CPL does in early and mid-lactation, but in late lactation the milk output from CPL does declined rapidly. This was the period of maximal fetal growth rates. Energy and N retention increased in P and CPL does in late pregnancy. 5. Regression analysis was carried out to summarize the relations between metabolizable energy intake (MEI) and energy retention (ER; MEI-heat loss) in each physiological state. The equations were: NP: ER = 0.67 (SE 0.057) MEI-208, P: ER = 0.67 (SE 0.095) MEI-224, L: ER = 0.90 (SE 0.022) MEI-441, CPL: ER = 0.85 (SE 0.036) MEI-387, where all variables are expressed in kJ/kg body-weight 0.75 per d.

Animals↗
PubMed1993

[The energy and nitrogen metabolism of pregnant and lactating sows and suckling piglets. 2. Chemical composition and energy content of the animal bodies of pregnant, non-pregnant and lactating sows].

The influence of litter number (1, 2 and 4, age of sows) as well as gestation and lactation stage of sows on the chemical composition and on the quantities of protein and fat of their bodies was investigated. The slaughter of 46 pregnant, 18 non-pregnant and 17 lactating sows were carried out at the 1st, 56th, 84th, 98th, 105th and 113th day of gestation, 113th day of experiment (non-pregnant sows) and 26th day of lactation. The results were related to the sows' energy supply (120, 100 and 80%) with equal supply of protein, vitamins and minerals. Within the tested litter numbers the chemical composition of the bodies was nearly constant during the whole time of gestation and lactation. A good agreement existed for the chemical composition of the sows' bodies of litter number 1 and 2. In comparison to them the bodies of litter number 4 contained more protein and less fat per kg dry matter. The quantities of body protein and fat increased in the gestation and decreased in the lactation period, in each case the quantities of fat exceeded than the quantities of protein. The quantities of body protein increased with higher litter number. The quantities of body fat increased from litter number 1 to 2 and were nearly equal in the sows of litter numbers 1 and 4. Within one litter number the amounts of body protein and fat attained the same level in pregnant, non-pregnant and lactating sows.

Animals↗
PubMed1994

[Energy and nitrogen metabolism of pregnant and lactating sows in addition to the suckling piglets. 4. Chemical composition and energy content of the conception products, reproductive organs and the live weight gain or loss in pregnant or lactating sows].

The chemical composition and the energy content of the conception products, the reproductive organs and the live weight gains or losses of pregnant and lactating sows were determined in dependence on the litter number (1, 2 and 4) and the energy supply (120, 100 and 80% of requirement recommendation) of sows as well as on the course of gestation and lactation. The results will be used as a basis for factorial derivation of requirement recommendation. The deposition of protein and energy in the conception products in dependence on the time is characterized by an exponential function. The deposition of nutrients and energy in the conception products is increased with rising litter size. The deposition of nutrients and energy per fetus is lower in the litter number 1 than in the litter number 2 and 4. The energy supply in the selected limits has no significant influence on the litter size as well as on the intrauterine deposition of nutrients and energy. The litter number, the energy supply as well as the course of gestation and lactation influence considerably the weight, the chemical composition and the energy content in the mammary gland. The chemical composition and the energy content of the live weight gains or losses of pregnant and lactating sows are strong affected by the energy supply. The increased energy supply of the pregnant sows is connected with increased live weight gains and with increased contents of dry matter, fat and energy however decreased contents of protein in the live weight gains. The live weight losses of the lactating sows are connected with mobilisation of body fat and body protein. The proportion of body fat to body protein degradation is increased with increased losses of body weight. Regression equations are calculated for the relationships between course of gestation and lactation respectively and deposition of protein and energy in the conception products, reproductive organs and maternal live weight gains or losses of sows.

Animals↗
PubMed1982

Relationship between lactate arteriovenous gradient and tissue lactate content in subendocardial and subepicardial layers of the ischaemic in situ heart.

Myocardial lactate content and simultaneous evolution of a lactate arteriovenous gradient associated with incomplete obstruction of the left coronary bed were studied in dog hearts. Samples of blood were taken from a peripheral artery and the coronary sinus; transmural samples of myocardial tissue were obtained from the left ventricular wall by drill biopsy in animals under total cardiopulmonary by-pass. Lactate content was assessed in subendocardial and subepicardial layers separately. A 40 to 70% reduction in coronary flow induced a quick reduction and even an inversion of the positive lactate gradient while the tissue content, which was similar to the arterial content, rose considerably, chiefly in the subendocardial layer. Lactate accumulating in tissue was released into the blood approximately in proportion to the tissue concentration. The value of employing the lactate concentration difference between arterial blood and coronary sinus blood as an index of the severity and duration of myocardial ischaemia is discussed.

Animals↗