The metabolic fate of chlormadinone acetate in the baboon.

The metabolic fate of chlormadinone acetate (17alpha-acetoxy-6-chloro-4, 6-pregnadiene-3, 20-dione; CAP) was studied in intact and biliary fistula baboons. The steroid was labeled with 3H at position 1 and with 14C at the carboxyl moiety of the 17alpha-acetate, thus affording the opportunity to ascertain the loss of the 17alpha-acetoxy group and the fate of both labels. The averages of the radioactivity excreted, given as percentages of the amounts injected, and the standard deviations were as follows: In the urine of intact animals after 6 hours, 5.7 +/- 0.2% and 5.5 +/- 0.7% of the 3H and 14C were recovered, respectively. After 6 days, there was 17.5% of the 3H and 16.2% of the 14C in the urine plus 15.3% of the 3H and 16.4% of the 14C in the feces. In baboons with biliary fistulas, the total radioactivity excreted was 7.8 +/- 0.7% of the 3H and 11.6% of the 14C in the urine, and 30.9 +/- 4.4% of the 3H and 30.7% of the 14C in the bile after 6 hours. Glucosiduronates were the predominant conjugates in the urine and bile. The similarity in the urinary excretion of radioactivity in the first 6 hours in intact and biliary fistula animals, the relatively low excretion of radioactivity in the bile and after 6 days in the urine, and the low fecal excretion suggest that the metabolites of CAP are not involved in an extensive enterohepatic circulation in the baboon. Deacetylation of the 17alpha-acetate in CAP was detected in the early collection periods of the urine and bile and constituted a very small percentage of the injected compound. No significant oxygenation of CAP at position 1 was detected. The metabolism of CAP is discussed and compared to our previously reported data on the metabolism of progesterone, ethynodiol diacetate and medroxyprogesterone acetate and the data on other progestogens reported in the literature. It appears that the excretion of CAP is significantly slower in the baboon than that of the other progestogens. The amounts of glucosiduronates of CAP and/or its metabolites formed in vivo are less than those formed with the other progestogens. Also, the extent of deacetylation of the 17alpha-acetate of CAP is much less than that of the 3beta-acetate of ethynodiol diacetate.     

Steroid levels after intramuscular injection of radioactive estradiol-17beta, estrone, progesterone and testosterone in the bovine

Eight 2 year old Hereford cows from days 8 to 12 of the estrous cycle were injected intramuscularly with 5 ml of corn oil containing 5 mg of estradiol-17beta (two cows), estrone (two cows), progesterone (two cows) or testosterone (two cows). Each cow treated with estradiol received 494 microc of estradiol-17beta-6, 7 H3 and each cow treated with estrone received 492 microc of estrone-6, 7 H3. Each cow treated with progesterone or testosterone received 400 muc of H3 compound labeled in the 7 position. Total urine was collected by urethral catheterization of the cows treated with estrogens. Blood samples for plasma and serum were collected via jugular cannulae. Blood and urine samples from estrogen-treated cows were collected hourly for the first 24 hr, at 2 hr intervals for the next 26 hr, at 4 hr intervals for the next 12 hr and at 12 hr intervals until background was reached. Blood samples were collected hourly from 1 to 8 hr after injection from progesterone or testosterone-treated cows. Plasma and serum levels of radioactive estradiol-17beta, estrone, progesterone and testosterone were similar. Blood levels of radioactivity peaked at 2 hr post-injection in cows receiving estradiol-17beta and at 3 hr in cows receiving estrone. Blood levels of labeled estradiol-17beta and estrone were nondetectable by 54 hr and 83 hr, respectively. Peak urinary excretion of radioactivity was reached at 7 hr for estradiol-17beta and at 14 hr for estrone and nondetectable levels were reached by 95 hr for estradiol-17beta and 14 hr for estrone. At these times, 15.5% of the total dose of radioactive estradiol-17beta and 17.5% of the injected estrone had been excreted in the urine. Peak blood and urinary excretion levels were reached earlier for radioactive estradiol-17beta than for estrone, and excretion of estradiol-17beta was completed more rapidly. No difference was found in plasma and serum levels for any steroid studies; thus, endogenous steroid titers in blood plasma and serum are not different in the cow.     

Pharmacokinetics and metabolism of formestane in breast cancer patients

Formestane (Lentaron(R), 4-hydroxyandrostenedione) is a steroidal aromatase inhibitor used for treatment of advanced breast cancer. Clinically, it is administered as a depot form once fortnightly by intramuscular (i.m.) injection. To investigate the pharmacokinetics, bioavailability and metabolism of the drug, seven patients received single 250 mg i.m. doses of commercial formestane on Days 0, 21, 35, 49 and 63 of this trial. On Day 63, three of the patients received an additional single intravenous (i.v.) pulse dose of 1 mg of 14C-labelled formestane. The plasma kinetics after i.m. dosing confirmed a sustained release of formestane from the site of injection. Within 24-48 h of the first dose, the circulating drug reached a C(max) of 48.0+/-20.9 nmol/l (mean+/-S.D.; N=7). At the end of the dosing interval, after 14 days, the plasma concentration was still at 2.3+/-1.8 nmol/l. The kinetic variables did not significantly change during prolonged treatment. Intramuscular doses appear to be fully bioavailable. Following i.v. injection of 14C-formestane, the unchanged drug disappeared rapidly from plasma, the terminal elimination half-life being 18+/-2 min (N=3). Plasma clearance, CL was 4.2+/-1.3 l/(h kg) and the terminal distribution volume V(z) was 1.8+/-0.5 l/kg. The drug is mainly eliminated by metabolism, renal excretion of metabolites accounting for 95% of dose. The excretory balance of 14C-compounds in urine and faeces totals up to 98.9+/-0.8% of the i.v. dose after 168 h. The 14C-compounds in plasma and urine were separated by HPLC, and three major metabolites were submitted to structural analysis by MS, NMR and UV spectroscopy. One of the metabolites is the direct 4-O-glucuronide of formestane. The other two represent 3-O-sulfates of the exocons 3beta,4beta-dihydroxy-5alpha-androstane-17-one and 3alpha,4beta-dihydroxy-5alpha-androstane-17-one, their ratio being 7:3. These exocons are formed by stereoselective 3-keto reduction, accompanied by reduction of the 4,5-enol function. The exocons do not inhibit human placental aromatase activity in vitro.     

Metabolism of straight saturated medium chain length (C9 to C12) dicarboxylic acids

A method utilizing thin-layer chromatography, high performance liquid chromatography, and mass spectrometry was developed for the quantification of C9, C10, C11, and C12 dicarboxylic acids in serum, urine, and feces of human volunteers and rats after oral administration of the acids. The method allowed good resolution and measurement of the dicarboxylic acids at nanogram levels. In humans, excretion was independent of the dosage; about 60% of C9, 17% of C10, 5% of C11, and 1% of C12 were excreted in the urine during the first 12 hours after administration. The concentration of the acids in serum peaked between 2 and 3 hours. Excretion was also independent of dosage in rats. About 2.5% of C, 2.1% of C10, 1.8% of C11, and 1.6% of C12 were excreted in the urine over a period of 5 days. The serum concentration and the urinary excretion of the diacids reached a maximum at the second day after the oral dose. In both humans and rats, the dicarboxylic acids found in serum and urine were 2, 4, or 6 carbon atoms shorter than the corresponding administered diacid. This indicates that there was beta-oxidation of the ingested diacids to some extent. The administration of [1,9-14C]azeliac acid and of [10,11-3H]dodecandioic acid confirmed the occurrence of beta-oxidation, and led to elucidation of the fate of the ingested diacids that were not excreted as such in the urine.     

Metabolic fate of ethynodiol diacetate in the baboon.

The enterohepatic circulation and metabolism of ethynodiol diacetate (3beta,17beta-diacetoxy-17alpha-ethynyl-estr-4-ene) in baboons were studied following the intravenous injection of this contraceptive steroid labeled with 14C (4-position) and with 3H (in either the 3- or 17-acetoxy moieties). Bile and urine from four baboons with biliary fistulas and urine from four intact baboons were collected for 7 hours. On the average, 40% and 44% of the injected dose were excreted in the bile and urine, respectively. Only 48% was recovered in the urine of intact baboons. Analysis of these excretion rates indicates an insignificant enterohepatic circulation of this compound. The steroid was excreted mostly (over 80%) as a glucosiduronate in urine and bile. Very little excretion of the 3-acetoxy compound was detected in the urine or bile at any time interval. 17-Monoacetoxy compounds, however, were detected both in urine and bile, suggesting a difference in the rate of in vivo hydrolysis of the 17beta- vs. the 3beta-acetate.     

Metabolism of sialic acids from exogenously administered sialyllactose and mucin in mouse and rat

A mixture of N-acetyl-[4,5,6,7,8,9-14C]neuraminosyl-alpha (2-3(6]-galactosyl-beta (1-4-glucose[( 14C]sialyl-lactose) and N-acetylneuraminosyl-alpha (2-3(6]-galactosyl-beta(1-4)-glucit-1-[3H]ol(sialyl-[3H]lactitol) as well as porcine submandibular gland mucin labeled with N-acetyl- and N-glycoloyl-[9-(3)H]neuraminic acid were administered orally to mice. The distribution of the different isotopes was followed in blood, tissues and excretion products of the animals. One half of the [14C]sialyl-lactose/sialyl-[3H]lactitol mixture given orally was excreted unchanged in the urine. The other half was hydrolysed by sialidase and partly metabolized further, followed by the excretion of 30% of the 14C-radioactivity as free N-acetyl-[4,5,6,7,8,9-14C]neuraminic acid and 60% of this radioactivity in the form of non-anionic compounds including expired 14CO2 within 24 h. The 14C-radioactivity derived from the [14C]sialyl-lactose/sialyl-[3H]lactitol mixture which remained in the bodies of fasted mice after 24 h was less than 1%. In the case of well-fed mice, a higher amount of the sialic acid residues was metabolized. The bulk of radioactivity of the mucin was resorbed within 24 h. About 40% of the radioactivity administered was excreted by the urine within 48 h; 30% of this radioactivity represented sialic acid and 70% other anionic and non-anionic metabolic products. 60% of the radioactivity administered remained in the body, and bound 3H-labeled sialic acids were isolated from liver. Sialyl-alpha (2-3)-[3H]lactitol was injected intravenously into rats; the substance was rapidly excreted in the urine without decomposition. These studies show that part of the sialic acids bound to oligosaccharides and glycoproteins can be hydrolysed in intestine by sialidase and be resorbed. This is followed either by excretion as free sialic acid or by metabolization at variable degrees, which apparently depends on the compound fed and on the retention time in the digestive tract.     

Metabolism and pharmacokinetics of progesterone in the cynomolgus monkey (Macaca fascicularis)

[4-14C]Progesterone was administered to two cycling female monkeys during the luteal phase of the cycle, and blood and urine were sampled over a 24 h period. Progesterone had a volume of distribution of 1.75 +/- 0.3 L/kg, and a plasma elimination clearance of 0.06 +/- 0.03 L/kg/min. In comparison to the human, plasma progesterone binding was greater and progesterone clearance was slower in the cynomolgus monkey. The major unconjugated metabolite in plasma was 20 alpha-hydroxy-4-pregnen-3-one. In urine 6.2% of 14C-steroids were unconjugated, 2.3% of which were [14C]progesterone. Thin-layer chromatography (TLC) of conjugated metabolites in urine revealed that 24% had the mobility of sulfates, 19% that of glucuronides, and 52% were more polar. After hydrolysis of conjugates, a major fraction chromatographed with pregnanediol. However, despite evidence for the presence of a 20 alpha-hydroxyl group, none of the pregnanediol isomers could be identified among these 14C-steroids. Nevertheless, over 80% of urinary metabolites had sufficient analogy to pregnanediol to bind to an antiserum specific for ring D and the C-17 side-chain of pregnanediol.     

Radioimmunoassay for dexamethasone 17,21-dipropionate and its metabolites in plasma and urine after topical application

A sensitive radioimmunoassay for dexamethasone 17,21-dipropionate and its four metabolites in human plasma and urine has been developed using single anti-dexamethasone antiserum. The antiserum was obtained by immunizing rabbits with dexamethasone-3-oxime-bovine serum albumin conjugate. All of the endogenous steroids tested cross-reacted less than 0.07%. Before radioimmunoassay, dexamethasone 17,21-dipropionate and dexamethasone 17-propionate were hydrolyzed to dexamethasone, and 6 beta-OH-dexamethasone 17-propionate was hydrolyzed to 6 beta-OH-dexamethasone in 3% ammonia/methanol at 5 C for 16 h. A standard curve was established with a useful range between 0.005 and 2 ng in the case of dexamethasone, between 0.05 and 5 ng in the case of 6 beta-OH-dexamethasone. Measurement of plasma concentrations and percent urinary excretion of the metabolites in healthy men was performed following occlusive dressing of dexamethasone 17,21-dipropionate cream and ointment. The main metabolites in plasma were dexamethasone 17-propionate and dexamethasone, which increased gradually and reached maximum levels (160-200 pg/mL) at 24-32 h after application. The major metabolites observed in urine were 6 beta-OH-dexamethasone 17-propionate and 6 beta-OH-dexamethasone. Total percentage of their urinary excretions within 72 h after application amounted to 0.28-0.50% of the dose administered.     

Determination of the antihypertensive agent 1-(2-aminoethyl)-3-(2,6-Dichlorophenyl)thiourea in plasma and urine by high-performance liquid chromatography

A rapid, sensitive and specific normal-phase (adsorption) high-performance liquid chromatographic (HPLC) assay was developed for the determination of 1-(2-aminoethyl)-3-(2,6-dichlorophenyl)thiourea [I] in plasma and urine. The assay involves the extraction of the compound into methylene chloride from plasma or urine buffered to pH 10, and the HPLC analysis of the residue dissolved in methylene chloride—methanol—heptane (85:10:5). A 10-μm silica gel column was used with methylene chloride—methanol—heptane—ammonium hydroxide (85:10:5:0.1) as the eluting solvent. The effluent was monitored at 254 nm and quantitation was based on the peak height vs. concentration technique. The assay has a recovery of 64.5 ± 4.5% (S.D.) from plasma and 96.0 ± 6.3% (S.D.) from urine in the concentration range of 0.1–2 μg per ml and 2–40 μg per 0.1 ml of plasma and urine, respectively, with a limit of detection of 0.05–0.1 μg [I] per ml of plasma using a 1-ml specimen and 0.1 μg per ml urine using a 0.1-ml specimen, respectively. The assay was applied to the determination of plasma levels and urinary excretion of the compound [I] in dog following the oral administration of 28.8 mg of [I] · maleate per kg body weight.The HPLC assay was also used to determine the stability of [I] and for the measurement of a potential degradation product, clonidine [II] [2-(2,6-dichlorophenylamino)-2-imidazoline] in pooled human plasma stored at ?17°C, and pooled human urine stored at ?17°C and ?90°C, respectively.     

Volume expansion during NOS substrate donation with L-arginine: regulatory offsetting of renal response?

The responses to infusion of nitric oxide synthase substrate (L-arginine 3 mg.kg(-1).min(-1)) and to slow volume expansion (saline 35 ml/kg for 90 min) alone and in combination were investigated in separate experiments. L-Arginine left blood pressure and plasma ANG II unaffected but decreased heart rate (6 +/- 2 beats/min) and urine osmolality, increased glomerular filtration rate (GFR) transiently, and caused sustained increases in sodium excretion (fourfold) and urine flow (0.2 +/- 0.0 to 0.7 +/- 0.1 ml/min). Volume expansion increased arterial blood pressure (102 +/- 3 to 114 +/- 3 mmHg), elevated GFR persistently by 24%, and enhanced sodium excretion to a peak of 251 +/- 31 micromol/min, together with marked increases in urine flow, osmolar and free water clearances, whereas plasma ANG II decreased (8.1 +/- 1.7 to 1.6 +/- 0.3 pg/ml). Combined volume expansion and L-arginine infusion tended to increase arterial blood pressure and increased GFR by 31%, whereas peak sodium excretion was enhanced to 335 +/- 23 micromol/min at plasma ANG II levels of 3.0 +/- 1.1 pg/ml; urine flow and osmolar clearance were increased at constant free water clearance. In conclusion, L-arginine 1) increases sodium excretion, 2) decreases basal urine osmolality, 3) exaggerates the natriuretic response to volume expansion by an average of 50% without persistent changes in GFR, and 4) abolishes the increase in free water clearance normally occurring during volume expansion. Thus L-arginine is a natriuretic substance compatible with a role of nitric oxide in sodium homeostasis, possibly by offsetting/shifting the renal response to sodium excess.     

The metabolism of 2-chloro-1-(2′,4′-dichlorophenyl)vinyl diethyl phosphate (Chlorfenvinphos) in the dog and rat

1. A single oral dose of [(14)C]Chlorfenvinphos to rats is quantitatively eliminated in 4 days. Rats do not show a sex difference in the elimination pattern and show only a small degree of biological variation in the total excretion data. Of the label 87.2% is excreted in the urine (67.5% in the first day after dosage), 11.2% in the faeces and 1.4% in the expired gases; less than 0.9% of (14)C is present in the gut and contents after 4 days. 2. After oral administration of [(14)C]Chlorfenvinphos to dogs, 94.0% (91.8-97.6%) of the (14)C is excreted in the urine and faeces during 4 days. Dogs do not show a sex difference in the pattern of elimination, and excretion of radioactivity in the urine is very rapid: 86.0% of (14)C during 0-24hr. 3. Chlorfenvinphos is completely metabolized in rats and dogs: unchanged Chlorfenvinphos is absent from the urine and from the carcass, when elimination is complete. In rats, 2-chloro-1-(2',4'-dichlorophenyl)vinyl ethyl hydrogen phosphate accounts for 32.3% of a dose of Chlorfenvinphos, [1-(2',4'-dichlorophenyl)ethyl beta-d-glucopyranosid]uronic acid for 41.0%, 2,4-dichloromandelic acid for 7.0%, 2,4-dichlorophenylethanediol glucuronide for 2.6% and 2,4-dichlorohippuric acid for 4.3%; in dogs, 2-chloro-1-(2',4'-dichlorophenyl)vinyl ethyl hydrogen phosphate accounts for 69.6%, [1-(2',4'-dichlorophenyl)ethyl beta-d-glucopyranosid] uronic acid for 3.6%, 2,4-dichloromandelic acid for 13.4% and 2,4-dichlorophenylethanediol glucuronide for 2.7%. 4. Dogs and rats show a species difference in the rate of excretion of (14)C in the urine, and in the proportions of the metabolites, with the exception of 2,4-dichlorophenylethanediol glucuronide, that are excreted in the urine. Alternative explanations for the latter species difference are suggested. 5. 2-Chloro-1-(2',4'-dichlorophenyl)vinyl ethyl hydrogen phosphate and 2,4-dichlorophenacyl chloride probably lie on the main metabolic pathway of Chlorfenvinphos, since, in common with that insecticide, they give rise to [1-(2',4'-dichlorophenyl)ethyl beta-d-glucopyranosid]uronic acid and 2,4-dichloromandelic acid as major metabolites in the urine. 6. The proposed scheme for the metabolism of Chlorfenvinphos represents a detoxication mechanism.     

Manipulation of citrulline availability in humans

To determine whether circulating citrulline can be manipulated in vivo in humans, and, if so, whether citrulline availability affects the levels of related amino acids, nitric oxide, urinary citrulline, and urea nitrogen, 10 healthy volunteers were studied on 3 separate days: 1) under baseline conditions; 2) after a 24-h treatment with phenylbutyrate (0.36 g.kg(-1).day(-1)), a glutamine "trapping" agent; and 3) during oral L-citrulline supplementation (0.18 g.kg(-1).day(-1)), in randomized order. Plasma, erythrocyte (RBC), and urinary citrulline concentrations were determined by gas chromatography-mass spectrometry at 3-h intervals between 1100 and 2000 on each study day. Regardless of treatment, RBC citrulline was lower than plasma citrulline, with an RBC-to-plasma ratio of 0.60 +/- 0.04, and urinary citrulline excretion accounted for <1% of the citrulline load filtered by kidney. Phenylbutyrate induced an approximately 7% drop in plasma glutamine (P = 0.013), and 18 +/- 14% (P < 0.0001) and 19 +/- 17% (P < 0.01) declines in plasma and urine citrulline, respectively, with no alteration in RBC citrulline. Oral L-citrulline administration was associated with 1) a rise in plasma, urine, and RBC citrulline (39 +/- 4 vs. 225 +/- 44 micromol/l, 0.9 +/- 0.3 vs. 6.2 +/- 3.8 micromol/mmol creatinine, and 23 +/- 1 vs. 52 +/- 9 micromol/l, respectively); and 2) a doubling in plasma arginine level, without altering blood urea or urinary urea nitrogen excretion, and thus enhanced nitrogen balance. We conclude that 1) depletion of glutamine, the main precursor of citrulline, depletes plasma citrulline; 2) oral citrulline can be used to enhance systemic citrulline and arginine availability, because citrulline is bioavailable and very little citrulline is lost in urine; and 3) further studies are warranted to determine the mechanisms by which citrulline may enhance nitrogen balance in vivo in humans.     

Androgen metabolism in the rhesus monkey.

A mixture of 3H-testosteron (T) and 14C-4-androstene-3, 17-dione (A) was injected intravenously into 2 (I and II) rhesus monkeys (Macaca mulatta). A third monkey (III) was injected with 3H-T only. Urine and bile samples were collected at intervals for 6 hours following the injection. The excretion, conjugation and aglycone metabolites of the steroids injected were studied using these samples. Of the injected dose, animal I (male) excreted 32% 3H and 23% 14C in the bile and 30% 3H and 21% 14C in the urine in 6 hours. Animal II (female), however, had a comparatively higher biliary excretion (66% 3H, 40% 14 C), but a urinary excretion (18% 3H, 13% 14C) comparable to that of animals I and III. The averages in the bile of the 3 animals were: unconjugated compounds 3%, glucosiduronates 78%, sulfates 9%, sulfoglucosiduronates 5% and disulfates 3%; and in urine, 5% unconjugated, 92% glucosiduronates and 3% sulfates. The aglycones obtained following hydrolysis were separated gy chromatography on Lipidex 5000, further purified by thin layer and paper chromatography and identified by co-crystallization. The major matabolites from 3H-T were androsterone and 5beta-androstane-3alpha,17beta-diol, whereas that from 14C-A was androsterone. Other metabolites identified were: etiocholanolone (3beta-hydroxy-5-beta-androstan-17-one); T, epitestosterone (epi-T), (17alpha-hydroxy-4-androsten-3-one); epiandrosterone (3-beta-hydroxy-5alpha-androstan-17-one) and 5alpha-androstane-3alpha, 17beta-diol. The results indicate that while androgen metabolism in the rhesus monkey is similar to that of the baboon and human in conjugate and metabolite formation, the rate of excretion was significantly different, resembline more closely that of the baboon than the human.     

Vasopressin inhibits diuresis induced by water immersion in humans.

We tested the hypothesis that 1-desamino-8-D-arginine vasopressin (DDAVP), a V2-receptor agonist, could inhibit the diuresis induced by water immersion in humans. Water and electrolyte excretion, plasma atrial natriuretic factor concentration, and plasma aldosterone concentration were measured initially and after 3 h of water immersion in 13 healthy sodium-replete men given either placebo or 20 micrograms of intranasal DDAVP. Guanosine 3',5'-cyclic monophosphate and urea excretion and urine osmolality were also determined. DDAVP inhibited the diuresis induced by water immersion in men: 758 +/- 168 (SE) ml/3 h in the placebo group vs. 159 +/- 28 ml/3 h in the DDAVP group (P less than 0.05). After 3 h of water immersion, plasma atrial natriuretic factor concentrations were increased from 11 +/- 2 to 20 +/- 4 pg/ml in the placebo group and from 14 +/- 2 to 33 +/- 4 pg/ml in the DDAVP group (P less than 0.05). Plasma aldosterone concentrations were decreased from 98 +/- 18 to 45 +/- 6 pg/ml in the placebo group (P less than 0.05) and from 54 +/- 17 to 25 +/- 5 pg/ml in the DDAVP group (P less than 0.05). Despite these changes in aldosterone and atrial natriuretic factor concentrations, which should increase sodium excretion, DDAVP decreased the natriuresis induced by water immersion in humans: 56 +/- 8 meq Na+/3 h in the placebo group vs. 36 +/- 6 meq Na+/3 h in the DDAVP group (P less than 0.05). DDAVP may be used to prevent the diuresis associated with central redistribution of blood volumes that occur during water immersion.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Disposition and metabolism of 16 beta-ethyl-17 beta-hydroxy-4-estern-3-one (TSAA-291), a new antiandrogen, in rats.

Matabolic fate of a new antiandrogen, 16 beta-ethyl-17 beta-hydroxy-4-estren-3-one (TSAA-291), was studied in rats. 14C-TSAA-291 intramuscularly injected as an aqueous suspension was absorbed gradually to give an increase in the plasma level which attained a plateau at 0.5 h, persisted till 8 h and then declined with an approx. half-life of 3.6 days. The drug was widely distributed in tissues, with the concns. almost equal to or higher than that in the plasma. The 14C-drug was eliminated mostly as metabolites within 10 days after dosing with higher activities found in the feces than in urine. Biliary 14C effectively underwent enterohepatic cycling. Biliary metabolites of TSAA-291 were characterized by the combined use of deuterium labeling and GLC-MS analysis. The metabolites identified were as follows: the parent drug, monohydroxy TSAA-291 having the additional hydroxy function in the steroid skeleton, 17 beta-hydroxy-16 beta-(1 xi-hydroxyethyl)-4-estren-3-one, 16 beta-ethyl-17 beta-hydroxy-5 beta-estran-3-one, 16 beta-ethyl-17 beta-hydroxy-5 alpha-estran-3-one, 16 beta-ethyl-5 beta-estrane-3 alpha, 17 beta-diol, 16 beta-ethyl-5 alpha-estrane-3 alpha, 17 beta-diol, 16 beta-ethyl-3 alpha-hydroxy-5 beta-estran-17-one and 16 beta-ethyl-3 alpha-hydroxy-5 alpha-estran-17-one. Monoketodihydroxy and/or trihydroxy metabolites were also detected in the bile.     

Distribution, metabolism and excretion of [1-14C]dolichol injected intravenously into rats.

[1-14C]Dolichol mixed in vitro with rat serum and injected intravenously into rats was rapidly cleared from the circulation in a manner consistent with a two-compartment model. About 80% of the radioactivity recovered from animals killed after 1 day was in the liver, with smaller amounts being found in lung, carcass (internal organs removed), gastrointestinal tract and contents, and spleen. The kidneys, testes and heart contained little radioactivity, and the brain did not appear to take up any [1-14C]dolichol. The half-life for the turnover of radioactivity from [1-14C]dolichol in tissues varied considerably, being 2 days for the lung, 17 for liver and about 50 days for the carcass. After 1 day, and also after 4 and 21 days, most of the radioactivity in all tissues was as [1-14C]dolichol and as [1-14C]dolichyl fatty acyl ester, although a small amount of incorporation of [1-14C]dolichol radioactivity into phospholipids was also observed. Faeces collected over the first 4 days after injection contained 13% of the [1-14C]dolichol dose, but urine and expired air contained only small amounts of radioactivity. Radioactivity in faeces was nearly all as unchanged [1-14C]dolichol and as [1-14C]dolichyl fatty acyl ester. The [1-14C]dolichol remaining in liver after 21 days appeared to be in a pool (possibly lysosomes) where most of it was not subject to excretion.     

The effect of a synthetic steroid (trienbolone) on the rate of release and excretion of subcutaneously administered estradiol in calves (18).

With the objective of obtaining values for the rate of release and excretion of subcutaneously implanted estradiol and to relate them to the metabolic effect of the hormone, a study was carried out with young Jersey bull calves. After subcutaneous administration of lactose tablets (implants) containing tritiated estradiol (4 mCi in 20 mg estradiol) the activity was followed in plasma, urine and feces for 107 days. Three calves received implants containing 140 mg trienbolone in addition to the 20 mg estradiol. In the first group maximum plasma concentration of estradiol-17 beta was 3 nmol/1. In the other group it was only 0.33 nmol/1. In calves receiving estradiol as the only steroid, 95% of the activity was excreted within 20 days after implantation. In the other group collection of urine and feces had to be carried out for 107 days in order to account for all the implanted activity. No 3H could be detected in urine and feces samples collected from the estradiol group more than 31 days ater implantation. The feces and urine samples collected from calves in the estradiol-trienbolone group 107 days after implantation contained from 1.4 - 3 nCi per gram. The remarkably decreasing effect of trienbolone on the release of estradiol and its possible importance for the effect of subcutaneously administered estradiol are discussed.     

An isotopic study of oxalate excretion in sheep.

Intravenously injected 14C labelled oxalate was rapidly removed from the blood stream via the kidney in 2 sheep, 75% being cleared within 8 h. Mean daily urinary oxalate excretions over 5 days were 21-2 and 27-5 mg and the derived plasma oxalate concentrations were 52-6 and 74-4 mug/100 ml, respectively. Oxalate was both filtered and secreted by the renal tubule with oxalate/inulin ratios varying from 1-11 to 1-57 in 6 normal sheep. A large increase in calcium excretion induced by calcium borogluconate infusion over 5 days was accompanied by a small but consistent increase in urinary oxalate excretion relative to calcium. Oxalate in blood was to be found mainly in the plasma, there being a small (8%) proporation within erythrocytes. This is lower than that reported for man, and yet in its excretion of oxalate via the kidney the sheep appears to closely resemble man and dog.     

Monitoring ovarian function and pregnancy in Eld's deer (Cervus eldi thamin) by evaluating urinary steroid metabolite excretion

Direct radioimmunoassays (RIA) for urinary oestrone conjugates and pregnanediol-3 alpha-glucuronide (PdG) were used to study ovarian activity patterns and pregnancy in Eld's deer. In 2 does, urinary metabolite patterns were compared to temporal patterns of plasma LH, oestradiol-17 beta and progesterone. Preovulatory LH peaks occurred coincident with behavioural oestrus, and plasma progesterone secretion paralleled PdG excretion. Although plasma oestradiol-17 beta levels fluctuated between 5 and 10 pg/ml throughout the oestrous cycle, no preovulatory oestrogen surge was observed. Based on PdG excretion, non-conception oestrous cycles averaged 21.5 +/- 2.1 days (+/- s.e.m., n = 65); however, 2 of 13 does exhibited prolonged oestrous cycles (30.1 +/- 4.4 days; range 14-62 days, n = 14) characterized by sustained PdG excretion. Excluding these 2 females, the mean oestrous cycle was 18.5 +/- 0.3 days (range 14-23 days, n = 51). Behavioural oestrus (12-24 h duration) was observed in 42 of 65 cycles (64.6%), and always corresponded with intercyclic troughs in PdG excretion (2-5 days duration). Mean gestation duration (n = 10) was 33.5 +/- 0.4 weeks. PdG concentrations increased (P less than 0.05) by Week -32 (3rd week of gestation), plateaued between Weeks -31 and -25, increased (P less than 0.05) markedly by Week -22 and then rose steadily until parturition, declining (P less than 0.05) rapidly thereafter. Mean excretion of oestrone conjugates remained low until Week -30, increased (P less than 0.05) steadily to Week -24 (P less than 0.05) and then returned to baseline by Week -17. Increased (P less than 0.05) oestrone conjugates concentrations were detected again by Week -4 followed by a rapid increase to peak pregnancy levels by Week -1, declining (P less than 0.05) precipitously after parturition. The results confirm that the Eld's deer is seasonally polyoestrous with onset (January-March) and cessation (August-October) of regular, cyclic ovarian activity coinciding with increasing and decreasing daylengths, respectively. Urinary PdG excretion accurately reflects cyclic ovarian activity and markedly elevated concentrations of this metabolite provide an accurate index of pregnancy. The simultaneous monitoring of oestrone conjugates appears useful for estimating the stage of pregnancy and predicting parturition onset.