Pharmacokinetics of C14-olivomycin in the body of mice with lymphosarcoma (L10-1 strain)]

The pharmacokinetics of C14-olivomycin after its single intravenous administration to mice with lymphosarcome (LIO-I) was studied. It was shown that according to the specific radioactivity the organs may be placed in the following order: I hour after the antibiotic administration-the blood, liver, spleen, thymus, tumor, muscle; 3 hour after the administration-the liver, spleen, thymus, blood, tumor, muscle. Accumulation of olivomycin in the mouse organs was mainly in direct dependence on the dose of the antibiotic administered. Chromatography of the substances extraceted with ethylacetate from the urine collected at various periods after C14-olivomycin administration showed the presence of a new radioactive product (Rf 0.35-0.37) in addition to the unchanged antibiotic (Rf 0.53). Bioautographic analysis of the chromatograms showed that the product of C14-olivomycin conversion preserved its biological activity. The analysis of the substances extracted with ethylacetate from the liver, spleen and tumors 3 hours after the antibiotic administration reveiled (except of the liver) the presence of a spot with Rf corresponding to that of the initial drug.     

Effect of exogenous carnitine on carnitine homeostasis in the rat

The interaction of exogenous carnitine with whole body carnitine homeostasis was characterized in the rat. Carnitine was administered in pharmacologic doses (0-33.3 mumols/100 g body weight) by bolus, intravenous injection, and plasma, urine, liver, skeletal muscle and heart content of carnitine and acylcarnitines quantitated over a 48 h period. Pre-injection urinary carnitine excretion was circadian as excretion rates were increased 2-fold during the lights-off cycle as compared with the lights-on cycle. Following carnitine administration, there was an increase in urinary total carnitine excretion which accounted for approx. 60% of the administered carnitine at doses above 8.3 mumols/100 g body weight. Urinary acylcarnitine excretion was increased following carnitine administration in a dose-dependent fashion. During the 24 h following administration of 16.7 mumols [14C]carnitine/100 g body weight, urinary carnitine specific activity averaged only 72 +/- 4% of the injection solution specific activity. This dilution of the [14C]carnitine specific activity suggests that endogenous carnitine contributed to the increased net urinary carnitine excretion following carnitine administration. 5 min after administration of 16.7 mumol carnitine/100 g body weight approx. 80% of the injected carnitine was in the extracellular fluid compartment and 5% in the liver. Plasma, liver and soleus total carnitine contents were increased 6 h after administration of 16.7 mumols carnitine/100 g body weight. 6 h post-administration, 37% of the dose was recovered in the urine, 12% remained in the extracellular compartment, 9% was in the liver and 22% was distributed in the skeletal muscle. In liver and plasma, short chain acylcarnitine content was increased 5 min and 6 h post injection as compared with controls. Plasma, liver, skeletal muscle and heart carnitine contents were not different from control levels 48 h after carnitine administration. The results demonstrate that single, bolus administration of carnitine is effective in increasing urinary acylcarnitine elimination. While liver carnitine content is doubled for at least 6 h following carnitine administration, skeletal muscle and heart carnitine pools are only modestly perturbed following a single intravenous carnitine dose. The dilution of [14C]carnitine specific activity in the urine of treated animals suggests that tissue-blood carnitine or acylcarnitine exchange systems contribute to overall carnitine homeostasis following carnitine administration.     

Effect of excess and deficiency of vitamin A on the utilization of FFA by liver and skeletal muscle.

Fatty acid metabolism in liver and skeletal muscle has been studied in rats treated with high doses of vitamin A and in those made vitamin A-deficient. Ingestion of 30,000 IU of vitamin A for two days resulted in increased incorporation of palmitate-1-14C into triglycerides but not into phospholipids. Accumulation of hepatic triglycerides was observed in vitamin A-fed rats. Deficiency of vitamin A did not cause any change in the triglyceride or phospholipid content of the liver. The rate of hepatic fatty acid oxidation and ketogenesis was markedly increased in vitamin A-fed rats. The experimental evidence indicated that vitamin A may have a stimulatory effect on these processes apart from that exerted by the high plasma FFA level in vitamin A-fed rats. Oxidation of palmitate-1-14C into C32 by skeletal muscle (latissimus dorsi) was also increased as a result of vitamin A administration. Vitamin A deficiency did not cause any change in fatty acid oxidation by liver and skeletal muscle. Hepatic palmitoyl-CoA synthetase activity was decreased in vitamin A-deficient rats. The results presented suggest that vitamin A may be required for the uptake and utilization of fatty acids by liver and akeletal muscle.     

14C] Alanine incorporation into proteins and their contents in the tissue of intact and adrenalectomized rabbits after hydrocortisone and cortitropin administration

A single administration of hydrocortisone to intact rabbits increases the incorporation of [14C] alanine into proteins of the brain and liver tissue homogenates and soluble fractions as well as in blood plasma proteins and reduces the label incorporation into the brain tissue proteins and reduces its incorporation into the blood plasma proteins. Adrenalcetomy is followed by an increase in the incorporation of [14C] alanine into proteins of the brain and muscle tissue homogenates and soluble fraction and into proteins of blood plasma and liver tissue homogenates as well as by reducing the label incorporation into the spleen soluble fraction proteins. ACTH administered to adrenalectomized rabbits reduces incorporation of [14C] alanine into the brain and muscle tissue proteins, total proteins of liver tissue homogenate and increases it into the proteins of the spleen tissue soluble fraction. Multiple administration of the soluble fraction hormones both to intact and adrenalectomized rabbits inhibits the label incorporation into the studied tissue proteins. Parallel with the change in [14C] alanine incorporation into proteins under the hormones effect certain shifts in their contents were also established.     

Rate of concentration and digestion of radioactive growth hormone preparations injected in rats,as measured by the amount and nature of radioactivity in the tissues

Summary The distribution of radioactivity in the tissues of the rat has been established after the administration of radioactive bovine growth hormone preparations.Bovine growth hormone was used either transformed in to a¹⁴C-guanidinated derivative, which was fully active, of labeled with less than 1 mole per mole of¹²⁵I.The tissue radioactivity distribution curves obtained belong to two different categories: in kidney, liver and spleen there is an early concentration which attains a maximum in 15 minutes after the injection of the hormone, and rapidly declines. In heart, skeletal muscle, pancreas, intestine, bone and fat, the radioactivity increases gradually and a steady-state is reached after 30 to 60 minutes.Kidney is the organ where the highest concentration of radioactivity occurs. However, muscle accumulates more than 60% of the initial doses after 2 hours. Very little radioactivity appears in the urine, in this period.Similar results have been obtained with pharmacological or physiological doses of the labeled hormones.Blood plasma does not degrade the injected hormone but kidney, liver and muscle rapidly produce radioactive fragments soluble in 10% trichloro-acetic acid.Dedicated to ProfessorLuis F. Leloir on the occasion of his 70^th birthday.     

Trafficking of dietary oleic, linolenic, and stearic acids in fasted or fed lean rats

Increasing evidence supports the notion that there are significant differences in the health effects of diets enriched in saturated, as opposed to monounsaturated or polyunsaturated fat. However, the current understanding of how these types of fat differ in their handling by relevant tissues is incomplete. To examine the effects of fat type and nutritional status on the metabolic fate of dietary fat, we administered (14)C-labeled oleic, linolenic, or stearic acid with a small liquid meal to male Sprague-Dawley rats previously fasted for 15 h (fasted) or previously fed ad libitum (fed). (14)CO(2) production was measured for 8 h after tracer administration. The (14)C content of gastrointestinal tract, serum, liver, skeletal muscle (soleus, lateral, and medial gastrocnemius), and adipose tissue (omental, retroperitoneal, and epididymal) was measured at six time points (2, 4, 8, 24, and 48 h and 10 days) after tracer administration. Plasma levels of glucose, insulin, and triglyceride were also measured. Oxidation of stearic acid was significantly less than that of either linolenic or oleic acid in both the fed and fasted states. This reduction was in part explained by a greater retention of stearic acid within skeletal muscle and liver. Oxidation of oleate and stearate were significantly lower in the fed state than in the fasted state. In the fasted state, liver and skeletal muscle were quantitatively more important than adipose tissue in the uptake of dietary fat tracers during the immediate postprandial period. In contrast, adipose tissue was quantitatively more important than skeletal muscle or liver in the fed state. The movement of carbons derived from dietary fat between tissues is a complex time-dependent process, which varies in response to the type of fat ingested and the metabolic state of the organism.     

Some biochemical effects of triamcinolone acetonide on rat liver and muscle

1. The powerful anti-inflammatory glucocorticoid triamcinolone acetonide, administered to rats at 20 and 2.5mg/kg, leads to a decrease in the incorporation in vivo of [(3)H]uridine and [(32)P]orthophosphate into hind-limb skeletal muscle. 2. At the higher dose, this decrease in the rate of incorporation of precursors into RNA precedes a decrease in the incorporating ability of muscle ribosomes, which commences about 4-5h after drug administration, but is unaccompanied by any changes in the concentration of tissue ATP or free amino acids. 3. The ribosomal dysfunction extends to polyribosomes, which can only be successfully isolated from the muscle of triamcinolone-treated animals after the addition of alpha-amylase to the tissue homogenate to remove glycogen. 4. The specific radioactivity of muscle protein labelled in vivo with (14)C-labelled amino acids does not decrease progressively after triamcinolone administration. After 2h there is an apparent stimulation of incorporation which leads to an overall discrepancy between measurements of protein-synthetic activity made in vivo and in vitro. 5. There is a significant increase in muscle-glycogen concentration between 8 and 12h after the administration of triamcinolone acetonide (20mg/kg), although a significant decrease occurs after 4h. The fall in glycogen concentration may be due to a decrease in the rate of synthesis of protein essential for glucose uptake into the tissues. 6. As judged by (a) incorporation of (14)C-labelled amino acids into protein, (b) [(3)H]uridine and [(32)P]-orthophosphate incorporation into RNA, (c) the rate of induction of tryptophan pyrrolase and (d) changes in the pool sizes of taurine and tryptophan, the responses in liver followed the same time-course as those in muscle after administration of the drug.     

Growth hormone effects on creatine uptake by muscle in the hypophysectomized rat

Summary Specific radioactive enzyme assays were developed to measure the effect of growth hormone on kidney transamidinase and liver methyltransferase in the hypophysectomized rat. In contrast to minimal changes (20%) in liver methyltransferase, kidney transamidinase was decreased threefold in the hypophysectomized rat. Enzyme activities were equal to normal values in those rats receiving growth hormone for three days. The formation of creatine from radioactive precursors and the uptake of ¹⁴C-creatine in muscle was examined under these conditions. After injection of ¹⁴C-arginine in the hypophysectomized rat, the ¹⁴C-creatine content of muscle was greatly decreased compared to sham operated controls and the ¹⁴C-creatine content was normal after growth hormone administration. After injection of ¹⁴C-guanidoacetate and of ¹⁴C-creatine, the ¹⁴C-creatine content of muscle was decreased in the hypophysectomized rat, but was equal to sham control values in rats receiving growth hormone. These studies indicate that the uptake of newly synthesized creatine by muscle is impaired in the hypophysectomized rat and that growth hormone can have a role in controlling the rate of creatine uptake by muscle in addition to its effect on kidney transamidinase and to other factors involved in creatine metabolism.     

Hypoglycemic effect of isoleucine involves increased muscle glucose uptake and whole body glucose oxidation and decreased hepatic gluconeogenesis

Isoleucine, a branched chain amino acid, plays an important role in the improvement of glucose metabolism as evidenced by the increase of insulin-independent glucose uptake in vitro. This study evaluated the effect of isoleucine on glucose uptake and oxidation in fasted rats and on gluconeogenesis in vivo and in vitro. Oral administration of isoleucine decreased the plasma glucose level by 20% and significantly increased muscle glucose uptake by 71% without significant elevation of the plasma insulin level compared with controls at 60 min after administration. Furthermore, expiratory excretion of 14CO2 from [U-14C]glucose in isoleucine-administered rats was increased by 19% compared with controls. Meanwhile, isoleucine decreased AMP levels in the liver but did not affect hepatic glycogen synthesis. Under insulin-free conditions, isoleucine significantly inhibited glucose production when alanine was used as a glucogenic substrate in isolated hepatocytes. This inhibition by isoleucine was also associated with a decline in mRNA levels for phosphoenolpyruvate carboxykinase and glucose-6-phosphatase (G6Pase) and a decreased activity of G6Pase in isolated hepatocytes. These findings suggest that a reduction of gluconeogenesis in liver, along with an increase of glucose uptake in the muscle, is also involved in the hypoglycemic effect of isoleucine. In conclusion, isoleucine administration stimulates both glucose uptake in the muscle and whole body glucose oxidation, in addition to depressing gluconeogenesis in the liver, thereby leading to the hypoglycemic effect in rats.     

Effect of lead in water on the absorption of copper, iron, manganese and zinc by sheep (Ovis aries) infected with sheep tapeworm (Moniezia expansa)

The sheep tapeworm (Moniezia expansa) and its host Ovis aries were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) for their copper, iron, manganese, zinc and lead levels. Element concentrations in cestode parasites were compared to those in various organs (liver, kidney, and muscle) of sheep. Tapeworms in the small intestine of sheep that were administered 2g of Pb(CH(3)COO)(2) per os daily (7 days) had significantly higher lead concentrations than sheep tissues. Cu levels significantly increased after Pb administration in sheep muscle and sheep tapeworms. Contrarily, Zn content significantly decreased in sheep muscle, but significantly increased in sheep tapeworms. However, Mn content significantly decreased after Pb administration in sheep tapeworms. Furthermore, Fe content significantly decreased after Pb administration in sheep liver and kidneys.     

Differential Contribution of Insulin and Amino Acids to the mTORC1-Autophagy Pathway in the Liver and Muscle

Autophagy is a highly inducible intracellular degradation process. It is generally induced by nutrient starvation and suppressed by food intake. Mammalian (or mechanistic) target of rapamycin complex 1 (mTORC1) is considered to be the major regulator of autophagy, but the precise mechanism of in vivo regulation remains to be fully characterized. Here, we examined the autophagy-suppressive effect of glucose, insulin, and amino acids in the liver and muscle in mice starved for 1 day. Refeeding after starvation with a standard mouse chow rapidly suppressed autophagy in both tissues, and this suppression was inhibited by rapamycin administration almost completely in the liver and partially in muscle, confirming that mTORC1 is indeed a crucial regulator in vivo. As glucose administration showed no major suppressive effect on autophagy, we examined the role of insulin and amino acids using hyperinsulinemic-euglycemic clamp and intravenous amino acid infusion techniques. Insulin administration showed a clear effect on the mTORC1-autophagy pathway in muscle, but had only a very weak effect in the liver. By contrast, amino acids were able to regulate the mTORC1-autophagy pathway in the liver, but less effectively in muscle. These results suggest that autophagy is differentially regulated by insulin and amino acids in a tissue-dependent manner.     

Interorgan transport and catabolism of carnosine and anserine in rainbow trout.

1. After large amounts of carnosine or anserine were injected into rainbow trout white muscle, they were promptly washed out into blood and incorporated mainly into kidney. 2. These dipeptides were transported only a little to the other portions of white muscle but significantly to red muscle. 3. After anserine administration, pi-methyl-L-histidine, a constituent of anserine, increased largely in the kidney, followed by liver and muscles. 4. Histidine, a decomposed product of carnosine, increased in muscles after carnosine administration prior to the increase in kidney and liver.     

Purine nucleotide catabolism in rat liver: labelling of uric acid and allantoin after administration of various labelled precursors

Uric acid and allantoin are the key compounds of purine nucleotide catabolism formed in liver and many other organs of the rat. We observed that, after administration of 14C-formate, incorporation of radioactivity into uric acid and allantoin is not similar, as one would expect. The phenomenon was demonstrated to be specific to liver and perfused liver, and not to other organs such as heart, jejunal mucosa, lung, spleen, and kidney. To interpret these results, the specific radioactivity of uric acid and allantoin in rat liver were analysed comparatively, after administration of the following labelled precursors: 14C-glycine, 14C-formate, 14C-hypoxanthine, 14C-uric acid and 14C-adenine. After administration of 14C-formate the specific radioactivity of allantoin was higher than that of uric acid and the same behavior was observed after 14C-uric acid and 14C-hypoxanthine, but not after 14C-glycine and 14C-adenine administration. The results indicate that the rate of their incorporation into uric acid and allantoin, and the subsequent export of these compounds into serum, can only partially explain the observed phenomenon, while the presence of different pools of uric acid and allantoin may give a complete explanation.     

Protein Metabolism in the Domestic Fowl

The metabolic half lives of glycine in the tissue-proteins of the rooster were determined by single oral dose of 2-C¹⁴ glycine before measuring the amount of synthesized glycine in the rooster by ?constant pool? method. The specific activity of glycine originated from the purine ring of uric acid showed the highest value for 5 hrs. after administration, following rapid decrease until 7 days, thereafter slower one.

Although the specific activity of glycine in the tissue protein (serum and liver) decreased exponentially, its trend was not distinct in the pectoral muscle, and in the early period its decrease seemed to be considerably fast (t_1/2 about 6 days).

The specific activities of glycine in the serum protein were always higher than those in the liver protein. The metabolic half livers obtained were as follows. Liver: Faster 2 days, slower 11 days. Serum: faster 2 days, slower 11 days. Pectoral muscle: faster 6 days, slower 30 days. Recovery of C¹⁴ into 4-C and 5-C in the purine ring of excreted uric acid during 24 hours after the administration of isotope was about 24%.     

Hormonal effects on gluconeogenesis from (U-14C)glutamate in rainbow trout (Salmo gairdneri)

Blood glucose was significantly decreased by insulin (4 I.U./kg). Glucagon (1 mg/kg) and Cortisol (5 mg/kg) administration produced a significant hyperglycaemia. Insulin administration did not modify liver glycogen levels. Glucagon showed a marked liver glycogen mobilization. Cortisol stimulated liver glycogen deposition. Insulin and Glucagon showed a significant inverse effect on gluconeogenesis from (U-14C)glutamate, decreasing and increasing 14C-glucose formation respectively. Hormonal treatments did not influence the very low levels of incorporation of (U-14C)glutamate into liver and muscle glycogen.     

Differential binding of monoiodinated insulins to muscle and liver derived receptors and activation of the receptor kinase

The binding affinity of monoiodoinsulin analogues to receptors purified from rat skeletal muscle and liver were compared. Insulin iodinated at tyrosine B26 bound to both muscle and liver derived insulin receptors with higher affinity than the A14-iodoisomer or native insulin. The affinity of the B26-iodoanalogue was greater for muscle than for liver derived receptors; by Scatchard analysis the affinity ratio B26/A14 was 2.8 for muscle and 1.3 for liver. The affinity of muscle and liver derived receptors for A14-iodoinsulin was not different. Dose response curves of autophosphorylation and exogenous tyrosine kinase activation showed significantly increased sensitivity to the B26-iodoanalogue (compared to the A14-iodoisomer or native insulin) in muscle derived receptors, but not in liver. The difference in affinity between muscle and liver derived insulin receptors towards B26-monoiodotyrosyl-insulin likely reflects the observed structural difference between the insulin receptor alpha-subunits from muscle and liver.     

Incorporation of orotic acid into nucleotides and RNA in mouse organs during 60 minutes.

Mouse kidney and liver were found to increase their levels of radioactivity above that of serum from 2 to 60 min after administration of [6-14C]orotic acid. In spleen, thymus and brain, the radioactivity level reached a maximum soon after the injection and then decreased, as did that in serum. Sixty minutes after the injection, 44% of the administered isotope dose was found in the kidneys, 22% in the liver and 0.75% in the spleen. The 14C activity in liver UTP increased rapidly and then remained constant for 60 min. The ratio between the activities in uridine phosphates and UDP-sugars was 3:4 from 10- 60 min after injection. In the liver and kidneys, the RNA 14C activities at 60 min after injection were 15% of the activity in their acid-soluble fractions. Intraperitoneal administration was found to be preferable to intravenous administration for studies on nucleotides and RNA in mouse liver, due to the delayed incorporation of the [14C]orotic acid activity into the nucleotide pool.     

Comparative accumulations of labelled carotenoids (14C-astaxanthin, 3H-canthaxanthin and 3H-zeaxanthin) and their metabolic conversions in mature female rainbow trout (Oncorhynchus mykiss).

1. One force-fed meal containing labelled 14C-astaxanthin (14C-Ax) and 3H-canthaxanthin (3H-Cx) or 3H-zeaxanthin (3H-Zx) was given to eight mature female rainbow trout. Ninety-six hours after the test meal ingestion, trout were killed and liver, skin, muscle and ovaries were dissected out. 2. Ax accumulated slightly more in muscle than Cx but in all tissues Ax and Cx were very significantly more concentrated than Zx. 3. 3H-Zx metabolites were found only in the liver, whereas 14C-phoenicoxanthin was the only metabolic pigment from 14C-Ax detected and was found in all investigated tissues. 4. 3H-Ax was found in the liver of all trout indicating that 3H-Cx and 3H-Zx were Ax precursors, and that salmonids probably possess carotenoid oxidative pathways unknown until now. 5. Labelled retinol1 and retinol2 were detected only in the liver and 3H-Zx was largely the predominant precursor of these two vitamin A forms.     

Fate of radioactivity in Atlantic Salmon (Salmo salar) following intragastric administration of (methyl-14C)-trichlorfon

The antiparasitic drug Neguvon® (Bayer), with the active component trichlorfon (0,0-dimethyl-(1-hydroxy-2,2,2-trichloroethyl)-phosphonate), is extensively used in fish farms in Norway. The fate of (methyl-¹⁴C)-trichlorfon was tested in Atlantic salmon (Salmo salar) by liquid scintillation counting at day 1, 4, 7, 14, and 30 post administration, and by autoradiography on selected organs 24 h after administration. The remaining radioactivity was found to be high compared to earlier measurements of the trichlor)fon content made by gas chromatography (Brandal 1977). The grains in autoradiographic preparations of muscle were unevenly distributed both in the muscle as a whole and within muscle fibers. In liver the grains were evenly distributed, but were absent from fat vacuoles. The study indicate that the radioactive residues in salmon muscle do not represent trichlorfon or its derivative dichlorvos (0,0-dimethyl-0-(2,2-dichlorovinyl)-phosphate), but rather hydrophilic metabo)lites of these compounds.     

Tissue distribution of acebutolol in mature normotensive and stroke-prone spontaneously hypertensive rats

Tissue distribution of acebutolol was studied in 33-week-old normotensive (WKY) and Okamoto stroke-prone (SHR-SP) rats, 30 min after an i.v. administration, by using 14C-acebutolol. Plasma level of acebutolol was higher in WKY than in SHR-SP. Aorta, kidney, liver and muscle radioactivity/plasma radioactivity ratios were higher in SHR-SP than in WKY. The brain/plasma radioactivity ratio was very low and similar in the two groups. The drug distribution was the same in the two groups except in medulla + corpus trapezoides where drug concentration was greater in SHR-SP. These results, compared with previous ones, show an age-related evolution in pathological state in SHR-SP. They point out a specific concentration of the beta-blocking drug in a defined part of the brain, namely medulla + corpus trapezoides.