Pre- and post-natal hepatic glucose phosphorylation in chicks (Gallus domesticus).

1. Hepatic glycogen levels and activities of metabolic enzymes were measured 7 d and 2 d before hatching, immediately after hatching and 4 d thereafter. 2. Chicken liver has a particle-bound hexokinase with a high K(m) (8 mM) for glucose. 3. The results indicate that the high-K(m) hexokinase is involved in the mitochondrial generation of ATP for glycogen and lipid synthesis.

Minor redistribution of ventilation and perfusion within the lung during exercise in sheep.

Considerable heterogeneity unrelated to the effect of gravity has been demonstrated for both local ventilation (V) and perfusion (Q) in the lung. Local ventilation and perfusion are well matched, so that the heterogeneity of the V/Q ratio is less than for ventilation or perfusion alone (Melsom et aL 1997). We are searching for the mechanisms responsible for the coordinate heterogeneity of ventilation and perfusion. Here, we ask how and to what extent physical exercise induces changes in the distribution of ventilation and perfusion. We measured local (approximately 1.5 cm3 tissue volume) pulmonary ventilation and perfusion simultaneously in six sheep before, during and after running on a treadmill. Local ventilation was determined from the deposition of labelled aerosol particles and local perfusion from trapping of radioactive microspheres. Cardiac output increased approximately 2.5-fold during exercise. V/Q-ratios were not normally distributed and we therefore present the heterogeneity as the interquartile range. At rest, the average interquartile ranges for local ventilation, perfusion and V/Q-ratio were 0.48, 0.51 and 0.39, respectively. During exercise, the corresponding values were 0.44, 0.40 and 0.32. Thus, the distribution of local V/Q-ratio was narrower than for ventilation and perfusion also during exercise. We found a moderate redistribution of relative flow towards the dorsal parts of the lungs when perfusion increased, but the increase in total perfusion and ventilation was for the most part throughout the lung. The results indicate that the coupling between local ventilation and perfusion is at least as potent during exercise as at rest. The correlation (r) between paired values in the two resting periods was 0.93 for ventilation and 0.91 for perfusion and thus indicates time stability for the two variables.

Apparent ruminal degradation and rumen escape of lysine, methionine, and threonine administered intraruminally in mixtures to high-yielding cows.

We studied the kinetics of lysine, methionine, and threonine in six high-yielding dairy cows at peak lactation (stage 1) and 6 mo later (stage 2). The cows were fitted with cannulas in the rumen and duodenum and were automatically fed every 4th h. The three amino acids (AA) were administered intraruminally in mixtures at dosages of 100, 200, 300, and 400 mmol of each, together with polyethylene glycol (PEG) as a liquid marker. Mean rumen liquid pools at stages 1 and 2 were not significantly different. The mean liquid outflow decreased from 13.6 to 9.5 L/h, and there was a significant linear increase in the liquid outflow with increasing dosages of AA. No significant interaction was found between feeding levels and AA dosages on rates of apparent degradation and rumen escape values. Expressed as percentages of the dosage, all three AA studied showed a significant linear decrease in degradation and a significant increase in rumen escape values with increasing dosage. At the feeding levels in stages 1 and 2, the highest relative degradation rates (percentage of dosage) were observed for threonine. The relative degradation rate of methionine was significantly lower than of lysine at the high feeding level but significantly higher at the low feeding level. The mean rumen escape values of threonine, methionine, and lysine across dosages and feeding levels were 16.7, 22.1, and 20.5%, respectively. The flow of the administered AA into the duodenum during an 8-h period after administration increased with increasing dosages, with peak concentrations after 1 h. Thus, the amounts of rumen escape of the three AA were considerable at all dosages, even when the AA were administered in unprotected form.

Ruminal escape and apparent degradation of amino acids administered intraruminally in mixtures to cows.

The apparent ruminal degradation and escape of amino acids (AA) administered in 9 different mixtures of essential AA and 8 different mixtures of nonessential AA were studied using two cows fitted with ruminal cannulas. The 600-mmol AA mixtures, which were administered intraruminally using polyethylene glycol as a liquid marker, contained equal amounts of two, four, or eight AA. The amounts of each of the AA in the mixtures were 300, 150, and 75 mmol, respectively. Ruminal degradation and escape were compared with values previously reported for AA administered individually. Across doses, the mean rate of initial degradation (degradation during the 1st h after administration) of essential AA was 26% when the AA were administered in mixtures and 45% when the AA were administered individually. For nonessential AA, the corresponding values were 34 and 54%. Across doses, mean ruminal escape during the first 8 h after essential AA administration was 22% when the AA were administered in mixtures and 16% when the AA were administered individually. For nonessential AA, the corresponding values were 13 and 11%. After intraruminal administration of AA, both individually and in mixtures, significant negative correlations were found between rates of degradation during the 1st h and ruminal escape during an 8-h period. Some AA mixtures caused a net increase in the concentration of other AA in ruminal fluid 1 h after administration. Twelve of the mixtures that did not contain Ala caused a considerable net increase in the concentration of this AA, and 3 AA mixtures containing Arg and Ala caused a marked net increase in the concentration of Trp.

Rumen escape and apparent degradation of amino acids after individual intraruminal administration to cows.

Apparent rumen degradation and escape of 18 amino acids (AA) after individual administration intraruminally were studied using two nonpregnant, nonlactating, rumen-cannulated cows fed a ration containing hay and concentrate twice daily. The pulse-dosages of AA were 75, 150, 300, and 600 mmol. Polyethylene glycol was used as the liquid marker. Rates of apparent degradation during the first 60 min (initial degradation) varied markedly among the AA; rates were highest for Ser, Asn, Glu, and Gln and lowest for Tyr, Val, Arg, and His. At the 75-mmol dosage, which corresponded to an initial substrate concentration of about 1 mM of rumen fluid, initial degradation varied between 95 and 40% of the dosage, depending on the AA. Rates, expressed as percentages of the dosage, decreased as dosages increased. During the first 8 h after administration, escape of the AA increased from a mean of 9% at the lowest dosage to a mean of 21% at the highest dosage. At the highest dosage, Met caused a net increase in the concentration of 11 of the other AA in rumen fluid. Twelve of the AA administered caused a net increase in the concentration of Ala in rumen fluid. Methionine and Lys are among the AA considered to be limiting to milk yield. These AA showed relatively high rumen escape values and may be useful as feed supplements even in an unprotected form.

Both gravity and non-gravity dependent factors determine regional blood flow within the goat lung.

Distribution of pulmonary blood flow has traditionally been regarded as determined by gravity. This view has been challenged recently by reports describing marked gravity-independent distribution of flow. These reports were based on experiments in which local blood flow was measured by methods that have not been thoroughly evaluated. In the present study, we showed that in the goat lung regional trapping of i.v. infused microspheres (O = 15 microns) correlated to endothelial uptake of a simultaneously i.v. infused diamine (r = 0.99, region size approximately 1.5 cm3, dry weight approximately 40 mg). This indicates that the deposition of microspheres reflects true regional pulmonary blood flow. Using the microsphere method, we found a marked gravity-independent heterogeneity in blood flow (coefficient of variation approximately 40%) in the awake goat. We could find no pattern related to anatomy that could account for this variability. We re-examined the influence of gravity by analysing the distribution of pulmonary blood flow in anaesthetized goats both in prone and supine positions. The dorsal to sternal distribution of flow appeared to be inverted when the animals were turned from prone to supine recumbency, indicating that gravity influenced the distribution of pulmonary blood flow along this axis. However, along the gravitational axis, distribution of blood flow varied considerably from lung to lung. It appears that in awake goats the distribution of pulmonary blood flow is the result of several different determinants.

Effects of recombinant human growth hormone on anorexic Nile crocodiles (Crocodylus niloticus).

1. Eleven-month-old Nile crocodiles with poor appetite and retarded growth were injected with 0.325 micrograms/g recombinant human growth hormone (hGH) twice a week for 4 weeks. 2. The treated animals had a mean intake per meal of 29.8 g/kg, while the controls ate only 2.8 g/kg. 3. The treated group gained 8.1% of their initial body weight, while the controls lost 6.3%. 4. During 4 weeks of treatment the body and head length increased by 3.93 and 1.29%, respectively, while no linear growth took place in the controls. 5. The treated group had higher contents of skeletal muscle protein and liver glycogen than the control group. 6. In conclusion, recombinant hGH induces appetite and growth in anorexic crocodiles.

Effect of iron treatment on erythrocyte parameters in postnatal anemia of the pig.

The development of postnatal anemia and the preventive and curative effect of iron supplementation were examined in 34 piglets from three litters of Norwegian Landrace pigs. A prostaglandin analog was given on day 111 or 112 of pregnancy, and the piglets were removed by caesarean section. Seventeen piglets were given 180 mg iron as colloidal ferridextran subcutaneously at birth (0 = day group); the remaining 17 were given the same amount on day 13 (13-day group). The piglets had access to a milk substitute from day 1 to day 7 and pelleted food for piglets after day 13. From about 4 weeks of age the piglets ate considerable amounts of pellets. The red blood cell count (RBC) and hemoglobin concentration (Hb) at birth were 3.2 +/- 0.4 (SD) x 10(12)/L and 80.4 +/- 8.1 x 10(12) g/L, respectively. In both groups Hb, RBC, mean corpuscular volume (MCV), and particularly packed cell volume (PCV) decreased markedly the first day after birth. In the 13-day group there was a further decrease until treatment with iron on day 13. Injection with iron on day 13 led to a rapid increase in the above mentioned parameters, with statistically significant increases for Hb, PCV, and MCV four days after treatment. The calculated mass of hemoglobin was fairly constant until treatment in the 13-day group. In the group given iron at birth the data obtained indicate that the amount of iron given is insufficient to sustain a production of normal-sized erythrocytes with a normal mean corpuscular hemoglobin concentration for more than approximately 21 days. Furthermore, the present study also indicates that MCV is a sensitive indicator of iron availability in piglets.

Effects of recombinant human growth hormone in juvenile Nile crocodiles (Crocodylus niloticus).

1. Recombinant human growth hormone (hGH) showed somatotropic activity in juvenile Nile crocodiles (Crocodylus niloticus). 2. Body weight of crocodiles receiving 3.25 micrograms hGH/g body weight twice a week was increased by 49% after five weeks of treatment, compared to 31% increase in controls. 3. Total length was increased by 15 and 5%, respectively, in the two groups. 4. Food conversion efficiency increased from 28% in the controls to 36% in the hormone injected animals. 5. Cessation of hormone treatment was followed by reduced appetite and decreasing body growth.

Threshold for shivering in aerobic and anaerobic muscles in bantam cocks and incubating hens.

Electromyographic activity (EMG) from the musculus pectoralis (breast muscle), m. iliotibialis (thigh muscle) and m. gastrocnemius (leg muscle), cloacal temperature (Tb) and O2 consumption were measured in bantam cocks (Gallus domesticus) exposed to different ambient temperatures (Ta). The same parameters were measured in bantam hens incubating eggs artificially thermoregulated to 40 degrees and 25 degrees C (Te). EMG activity appeared in thigh and leg muscles at Ta below 32 degrees C (Tsh). This temperature probably represents the thermoneutral temperature (TNT) of the cock. EMG activity in breast muscles appeared at Ta below 20 degrees C, or 4 degrees C below the lower critical temperature (Tc). All muscles were quiet when the hen incubated 40 degrees C egg at Ta = Tsh. When Te was abruptly changed to 25 degrees C, EMG activity in the iliotibialis muscle appeared 3 min before the activity in the pectoralis muscle. Tb dropped from 41.2 degrees to 40.6 degrees C in 14 min. When Te was returned to 40 degrees C, the EMG activity in the pectoralis muscle disappeared almost at once, while the iliotibialis muscle was active until Tb returned to normal. Aerobic muscles seem to be responsible for shivering thermogenesis between Tc and Tsh, while anaerobic muscles are recruited at lower Ta or when the heat loss during incubation becomes severe.

Effects of hypoxia on the metabolism of embryos and chicks of domestic fowl.

Oxygen consumption and blood lactate concentration were measured in embryos (days 17-20) and chicks (days 0-7) in air and in 7-8% O2. The specific oxygen consumption in air increased up to day 4 after hatching. In 7-8% O2, the consumption decreased for all ages. The reduction was largest in the embryo (19% of normal) and smallest in the newly hatched chick (78% of normal). Blood lactate concentration increased markedly during exposure to 7-8% O2 at all ages. Although the embryo exhibited the largest percentage reduction in aerobic metabolism during hypoxia, the blood lactate concentration increased to the same level as in the newly hatched chick. A positive correlation between reduction in aerobic metabolism and blood lactate concentration was found in chicks. Thus, during hypoxia the embryo seemed to be able to reduce its total metabolic rate to a much greater extent than after hatching.

Anaerobic metabolism in fowl embryos during normal incubation.

Lactate concentration in blood, liver, yolk, amniotic and allantoic fluid and blood pyruvate was measured in embryos in the final week of incubation. Blood lactate was low up to day 18. The blood lactate/pyruvate ratio and liver lactate increased from day 19 until hatching. From day 14 to 19, lactate concentration in amniotic fluid remained constant, it increased 2-fold in yolk and 10-fold in allantoic fluid. There was only a 48% net accumulation of lactate in the three cavities. In conclusion, fowl embryos do not turn to anaerobic metabolism until the hatching process starts on day 19.

The toxicity of non-ionic water-soluble contrast media in selective vertebral angiography. An experimental study in rabbits with special reference to the difference between monomeric and dimeric compounds.

Selective vertebral angiography was performed in 28 rabbits in order to compare the adverse effects of two monomeric (metrizamide, iohexol) and two dimeric (iodecol, 2-5410-3) non-ionic water-soluble contrast media. The dose was 2,5 ml and the iodine concentrations 300 mg per ml. Marked, but transitory changes were seen in the electrocardiographic and blood pressure recordings with all the contrast media and with no difference between them in this respect. The two monomers had a higher tendency than the dimers to cause spasm in the intracranial arteries. No serious complications were seen in the series.

Human pharmacokinetics of iohexol. A new nonionic contrast medium.

The pharmacokinetics of iohexol, a new nonionic, water-soluble contrast medium, have been determined after intravenous injection in 20 healthy volunteers, at four different dose levels (125-500 mg I/kg). The apparent volume of distribution was 0.27 1/kg, indicating distribution in the extracellular water. The biologic half-life was 121 minutes, comparable with that of other intravascular contrast media. Iohexol was excreted completely unmetabolized in the urine, with a 100% recovery 24 hours after injection. A comparison of iohexol and chromium-51 (51Cr)-EDTA clearances indicates that iohexol is mainly excreted by glomerular filtration. The 51Cr-EDTA clearance was the same when injected separately and concomitantly with iohexol, indicating that glomerular filtration rate is not affected by iohexol. No dose dependency was observed in the investigated parameters t1/2 alpha, t1/2 beta, Vd, ClT or ClR. Iohexol pharmacokinetics are in correspondence with previously reported data on intravascular contrast media.

Oxygen uptake in fowl eggs incubated in air and pure oxygen.

1. The oxygen uptake of small (bantam hen) and large (white leghorn) domestic fowl eggs was measured during incubation in air and pure O2. 2. A 2 hr exposure to pure O2 increased the O2-uptake from the 9th day in the large eggs and from the 15th day in the small eggs. 3. On the last 4 days of the incubation period, both small and large eggs increased their O2-uptake by about 22% when transferred from air to pure O2. 4. When 1 cm2 of the eggshell above the air cell was removed, the O2-uptake of the white leghorn eggs incubated in air increased by 13%.

Effect of iohexol, metrizamide and ioxaglate on the blood-brain barrier.

The effect upon the blood-brain barrier of the non-ionic contrast medium iohexol, compared with that of ioxaglate and metrizamide, was analysed. The contrast media were injected selectively into the internal carotid arteries of rabbits, and 197Hg Ac2 and Trypan blue were used as markers for evaluation of the injury. Less injury to the blood-brain barrier was caused by iohexol.