Ani Muscle Research Articles

Genomic organization, expression, and analysis of the troponin C gene pat-10 of Caenorhabditis elegans.

We have cloned and characterized the troponin C gene, pat-10 of the nematode Caenorhabditis elegans. At the amino acid level nematode troponin C is most similar to troponin C of Drosophila (45% identity) and cardiac troponin C of vertebrates. Expression studies demonstrate that this troponin is expressed in body wall muscle throughout the life of the animal. Later, vulval muscles and anal muscles also express this troponin C isoform. The structural gene for this troponin is pat-10 and mutations in this gene lead to animals that arrest as twofold paralyzed embryos late in development. We have sequenced two of the mutations in pat-10 and both had identical two mutations in the gene; one changes D64 to N and the other changes W153 to a termination site. The missense alteration affects a calcium-binding site and eliminates calcium binding, whereas the second mutation eliminates binding to troponin I. These combined biochemical and in vivo studies of mutant animals demonstrate that this troponin is essential for proper muscle function during development.

Unc-45 gene of Caenorhabditis elegans encodes a muscle-specific tetratricopeptide repeat-containing protein.

The unc-45 gene of the nematode, Caenorhabditis elegans, is essential for muscle organization and embryonic development. Genetic evidence suggests the unc-45 gene product controls muscle thick filament assembly. We report here on the determination of the gene's chromosomal location and the isolation and sequencing of its cDNA. The amino terminus of the predicted unc-45 protein contains three tandem repeats that belong in the tetratricopeptide repeat family. Tetratricopeptide motifs have been shown to be involved in protein interactions, and some of the closest homologues have chaperone-like activity. The carboxy terminus of the protein has homology with the related fungal proteins, CRO1 and She4p, which have been postulated to play a role in assembly of or interactions with a cytoplasmic myosin. We have also determined the sequence of the homologous gene from C. briggsae, which demonstrates a high level of conservation. We show that the unc-45 gene promoter can drive reporter gene expression, which is limited to muscle tissues (pharyngeal, body wall, vulval, and anal muscles), consistent with a role for the unc-45 gene in muscle development or function.

Absence of detectable pharmacological effects after oral administration of isoxsuprine.

Isoxsuprine is reported to be a peripheral vasodilator used in human and veterinary medicine to treat ischaemic vascular disease. In horses, it is generally administered orally to treat navicular disease and other lower limb problems. To define the scope and duration of its pharmacological responses after oral administration, 6 horses were dosed with isoxsuprine HCl (1.2 mg/kg bwt) q. 12 h for 8 days and then tested to assess the duration and extent of pharmacological actions. There was no significant difference between isoxsuprine and control treatment values for heart rate, spontaneous activity, sweat production, anal muscle tone, core and skin temperatures, and cutaneous blood flow. The lack of pharmacological effect following oral administration was in sharp contrast to the marked response following i.v. dosing reported in earlier experiments.

The anatomical basis of anal endosonography. A study in postmortem specimens.

Anal endosonography is an imaging modality new to the diagnostic workup of incontinence. Interpretations even of normal endosonomorphologic findings now vary considerably. The conjoined longitudinal muscle (LM), a widely ignored structure, has until recently not been fully recognized by anal endosonography. The aim of this study, therefore, was to accurately determine the normal anatomy of the anal canal and correlate it with the findings obtained by anal endosonography. Eight postmortem specimens of the anal canal were examined by endosonography. The findings were correlated with macroscopical dissection and gross sectional histology of the same specimens. The external echogenic ring is composed of two anatomical structures: the LM and the external anal sphincter (EAS). However, during anal endosonography the LM cannot always be differentiated from the EAS. Histologically, the relation of the diameters of the LM and the EAS ranged from 0.45:1 to 1.25:1. The narrow hyperechogenic ring between the inner hypoechoic layer and the external hyperechoic ring is an artificial finding that cannot be related to a distinct anatomical structure and most likely represents a sonographic interface. This study exactly outlines the relation of diameters of the conjoined longitudinal muscle and external anal sphincter for the first time. Until now, the LM has been underestimated in its dimensions. The role of such a thick muscular structure should be included in the conception of anal continence in the future. Especially in view of the fact that anal endosonography is increasingly used in the diagnostic workup of incontinence and fistula in ano, it is essential to understand the anatomical basis of endosonography. This study accurately delineates the sonomorphology of the anal muscles. When viewed in light findings reported here, endosonographic findings in diseases of the anal canal are nor based on a correct idea of the correlation between endosonomorphology and anal anatomy.

Evaluation of scheduled J-pouch irrigations on decreasing stool frequency after ileoanal pull-through and ileostomy closure

This study was intended to determine whether J-pouch irrigations through the efferent limb of the protective ileostomy stoma after ileoanal pull-through are effective in decreasing high stool frequency after ileostomy closure. Patients undergoing ileoanal pull-through may have high stool frequency after ileostomy closure. J-pouch irrigations through the efferent ileostomy stoma may decrease stool frequency by increasing J-pouch volume, improving storage capacity. The study used a randomized, prospective design in a university hospital outpatient setting. Participants ( N = 58) were randomly assigned to control and experimental groups. Effectiveness of irrigation was determined by stool frequency. Both groups were taught Kegel exercises (anal muscle strengthening exercises). The experimental group was taught how and when to irrigate the J-pouch daily; the control group was not. Forty-seven subjects, 25 men and 22 women ranging in age from 15 to 65 years, completed the study. Results of MANOVA indicated no significant between-group difference in the average number of times that subjects performed Kegel exercises; however, there was a significant decrease during the 4-week study period ( p < 0.001). There was no significant difference between groups in stool frequency, which decreased with time. There also was no significant effect on nocturnal leakage or satisfaction with surgical outcome. Additional clinical variables that were measured but had no significant effect included eating late, pouch size, and intake of sugar, fiber, bulk-forming products, and antidiarrheal agents. The study did not support the effectiveness of J-pouch irrigation in decreasing stool frequency after ileostomy closure. The cost, time commitment, and burden of performing daily irrigations are not warranted in this patient group.

Ciliary neurotrophic factor may act in target musculature to regulate developmental synapse elimination.

During development of mammalian skeletal muscles, synaptic contacts from different motoneurons are made on to individual muscle fibers but then are progressively lost until the adult pattern of single innervation is established. Although this process of synapse elimination occurs throughout the developing nervous system, little is known about the underlying mechanisms that drive this process. Competition for target-derived trophic substances has been proposed as one mechanism whereby synapses are selectively maintained or eliminated. To directly test whether exogenous trophic substance could alter neuromuscular synapse elimination, levator ani (LA) muscles of male rats were treated during the period of synapse elimination with either human recombinant ciliary neurotrophic factor (CNTF-a putative motoneuronal survival factor), or vehicle. LA muscles were stained with tetranitroblue tetrazolium at the end of treatment and the number of axonal inputs per muscle fiber was quantified. Effects of CNTF on other parameters such as body weight, axonal sprouting, muscle fiber and motoneuronal growth were also assessed. CNTF-treated muscles contained 3 times more multiple innervation than did vehicle-treated muscles, suggesting that CNTF can regulate synapse elimination in the LA. Moreover, CNTF delivered near the LA was more potent in blocking synapse elimination than the same dose of CNTF delivered at a site distant from the LA, suggesting that the target muscle is an important site, either for direct CNTF action on synapse elimination, and/or for directed transport of CNTF to motoneuronal cell bodies.

On the Vegetative and Sensitive Innervation of the Retractor Clitoridis Muscle in Some Domestic Animals

The retractor clitoridis muscle originates from the coccygeal vertebrae in the cow, ewe, goat and mare, and from the anal musculature in the sow. It terminates at the base of the clitoris. In all the species considered, a vegetative innervation was found. This was represented by isolated or grouped ganglion cells. Nervous sensitive supply was also present. This was represented by Pacinian, Pacinian-like and Golgi-Mazzoni's corpuscles, and by Krauses's end bulbs. A notable difference was found in the amount and type of these receptors. They were numerous in the sow, ewe and goat, and rare in the cow and mare. Additionally, in the sow, ewe and goat, all the above mentioned receptors were found, while, in the cow and mare, only Pacinian and Pacinian-like corpuscles occurred. The morphology of these receptors was described and hypotheses were made concerning their probable functional role.

The anal sphincter in patients with myotonic muscular dystrophy

The objective of this prospective study was to determine anal sphincter function and thickness of the anal musculature in patients with myotonic muscular dystrophy. Manometric studies were performed in 16 patients with myotonic dystrophy and in 16 healthy controls. Patients had significantly lower basal and squeeze pressures than control subjects (P < 0.01). The results of ultrasonographic studies of the anal canal in 7 patients and 7 control subjects suggest that this decrease in muscle strength is partly explained by muscular atrophy. In addition, patients with myotonic dystrophy showed exaggerated rebound contractions following anal sphincter relaxation that was induced by rectal distention. The pattern of this response and the results of electromyographic studies in 6 patients with myotonic dystrophy suggest that such abnormalities are explained by a neurogenic defect rather than a myotonic response of the anal musculature. It is concluded that patients with myotonic dystrophy show a multitude of defects in the anal sphincter that are an expression of myopathy, muscular atrophy, and neural abnormalities.

Does the distal rectal muscle in anorectal malformations have the functional properties of a sphincter?

Smooth muscle strips from the distal rectum of 11 patients who underwent surgery for imperforate anus and cloacal malformations, were studied in vitro to assess the motility response to electrical field stimulations (EFS) and to pharmacological stimulation with adrenergic and cholinergic agonists. EFS induced a nonadrenergic, noncholinergic inhibition in most strips. Acetylcholine caused either a modest contraction, no response, or a relaxation. Following atropine administration, acetylcholine caused a nonadrenergic and tetrodotoxin-resistant relaxation. The alpha-adrenergic agonist phenylephrine induced contractions in all strips. The response was abolished by alpha-adrenoceptor blockade with phentolamine, but was resistant to atropine and tetrodotoxin. beta-Adrenergic stimulation caused a relaxation that was abolished by propranolol. Function of the distal rectal smooth muscle, resected during correction of anorectal malformations, shows similarities to the function reported previously on normal anal smooth muscle evaluated in vitro.

Genetic analysis of defecation in Caenorhabditis elegans.

Defecation in the nematode Caenorhabditis elegans is achieved by a cyclical stereotyped motor program. The first step in each cycle is contraction of a set of posterior body muscles (pBoc), followed by contraction of a set of anterior body muscles (aBoc), and finally contraction of specialized anal muscles that open the anus and expel intestinal contents (Exp). By testing existing behavioral mutants and screening for new mutants that become constipated due to defects in defecation, I have identified 18 genes that are involved in defecation. Mutations in 16 of these genes affect specific parts of the motor program: mutations in two genes specifically affect the pBoc step; mutations in four genes affect the aBoc step; mutations in four genes affect the Exp step; and mutations in six genes affect both aBoc and Exp. Mutations in two other genes affect the defecation cycle period but have a normal motor program. Sensory inputs that regulate the cycle timing in the wild type are also described. On the basis of the phenotypes of the defecation mutants and of double mutants, I suggest a formal genetic pathway for the control of the defecation motor program.

Vertebral Lymphosarcoma as the Cause of Hind Limb Paresis in a Horse

A 23-month-old, 400-kg female quarterhorse was referred to the Louisiana State University Veterinary Teaching Hospital for recumbency due to rear limb paresis. Eleven days earlier, the owner had noticed transient abnormal head and neck posture, but no other abnormalities were noted until the animal suddenly became recumbent 3 days prior to referral. On physical examination, the horse was alert. Cranial nerve responses were normal, as were reflexes and cutaneous sensations of the forelimbs. There was paresis of the rear limbs, but patellar and withdrawal reflexes and sensory perception were intact. Tail control and anal muscle tone were normal. A complete blood count (CBC) revealed mature neutrophilia (16,400 white blood cells/μl, 90% segmenters), hyperfibrinogenemia (800 mg/dl), and hyperproteinemia (9.0 g/dl). With the exception of a slight elevation in creatine phosphokinase, the chemistry panel was normal, including calcium levels. Cerebrospinal fluid collected from the lumbosacral space was normal. A thoracolumbar spinal cord lesion was suspected and the horse was treated accordingly. No change in condition was seen in 24 hr and the animal was euthanized. Within the vertebral canal at the level of the first lumbar vertebra was an elongated, tan-white subperiosteal mass measuring 2 x 5 cm (Fig. 1). This mass had a glistening smooth surface (periosteum) and compressed the spinal cord at that point. Cross section of the first lumbar vertebra revealed destruction of the vertebral body and replacement by soft tan-white tissue. This tissue displaced and replaced trabecular bone in the vertebral body and at the base of the dorsal spinous process. Focal destruction of the cortex presumably allowed formation of the subperiosteal mass, which protruded into the vertebral canal. The spleen weighed 22 kg and contained a 30-cm-diameter round mass (Fig. 2). The surface of the splenic mass was smooth and mottled in color from red to tan to dark purple. There were 5 thick, sessile, discoid plaques present on the splenic mass and the adjacent capsule. The plaques were pale tan, 4-8 cm in diameter, flattopped, and elevated 2-4 cm above the capsular surface. Cut section of the mass and plaques revealed multiple coalescing round nodules of moderately soft tan tissue (Fig. 3). Nodules varied in size from 0.5 to 2 cm in diameter and were occasionally separated from one another by hemorrhage, giving the tissue an overall marbled tan and red appearance. Approximately 50% of the center of the mass was necrotic, as characterized by friable yellow-tan tissue and a 9-cm-diameter area of liquification necrosis. Mesenteric lymph nodes were enlarged and many contained multiple discrete cortical nodules up to 1.5 cm in diameter.

Increased glucocorticoid/androgen receptor ratios in denervated striated muscle

Cytosolic glucocorticoid (GR) and androgen receptors (AR) were evaluated at varying time intervals (1–28 days) post-denervation in rat bulbocavemosus/levator ani muscles and the receptor content in the unilaterally denervated muscles compared to the contralateral innervated muscles. Rats were adrenalectomized 3 days prior to GR or castrated 24 h prior to AR determinations. Receptor analyses were performed using charcoal adsorption. Lowered AR were noted in the denervated muscles during very early time periods post-denervation while increased GR were not observed until later. During later post-denervation intervals relative increases or decreases in receptors were dependent on the basis of data expression (cytosolic protein or DNA). The GR to AR ratio was consistently higher in denervated muscles regardless of the basis of comparison, however. We conclude that decreased responsiveness to anabolic stimuli may play a role in the atrophic process.

Effect of denervation or castration on steroid receptors in rat bulbocavernosus/levator ani muscles

Alterations in cytosolic glucocorticoid (GR) and androgen receptors (AR) in atrophic rat bulbocavernosus/levator ani muscles (BCLA) were investigated. The BCLA was removed 15 days after denervation (DEN) of the right part of BCLA or castration (CAS) and compared with the innervated left part of BCLA (INN) or the BCLA from sham-operated rats (SHAM). Receptor analyses were performed using charcoal adsorption or agar-gel electrophoresis. The main results were: (1) no alterations in K d were observed; (2) GR were increased in DEN compared to INN when expressed per mg cytosolic protein ( P < 0.0001) or g tissue ( P < 0.0002) as well as in DEN compared to SHAM when expressed per mg protein ( P < 0.0002) or g tissue ( P < 0.0003); (3) GR were increased in CAS compared to SHAM when calculated per mg protein ( P < 0.05) or g tissue ( P < 0.04); (4) no differences between DEN and INN or SHAM were noted when results were expressed per mg DNA; (5) AR were increased in CAS compared to SHAM only when expressed per mg protein ( P < 0.003); (6) GR/AR was increased in DEN compared to INN ( P < 0.0001) or SHAM ( P < 0.0006), but unaltered in CAS compared to SHAM. The data reflect differences in the behaviour of GR and AR in the atrophic BCLA and suggest a relative increase in sensitivity to glucocorticoids compared to androgens in the DEN muscle.

排便機能，特にこう門管静止圧，内こう門括約筋活動に与える下腹神経および仙骨神経の影響に関する実験的研究

排便機能，特にこう門管静止圧，内こう門括約筋活動に与える下腹神経および仙骨神経の影響に関する実験的研究

Dorsal Approach to the Caudal Pelvic Canal and Rectum Effect on Normal Dogs

A dorsal surgical approach to the perineal area and rectum was made on 10 healthy, adult dogs. The rectococcygeal muscle was incised and the levator ani and external sphincter muscles were separated to the level of the caudal rectal nerve. All dogs were clinically normal throughout a 3 week postoperative observation period.

Sexual activity influences organ weight and androgen metabolism of rat prostate, bulbocavernosus/levator ani muscle and kidney

Previously we have shown that rats living under heterosexual conditions (HE-rats) have significantly higher weights of androgen target organs like prostate and bulbocavernosus/levator ani muscle (BCLA) than rats living under homosexual conditions (HO-rats). Knowing that androgen metabolism is an important regulator of androgenic action, we have measured in vitro by thin-layer chromatography the testosterone 5α-reductase and 3α(β)-hydroxysteroid dehydrogenase (3α(β)-HSDH) activity in prostate and BCLA of both groups. Furthermore, we looked for weight differences of the kidney from HE- and HO-rats. The main results are: (1) The mean apparent Michaelis constant ( K m ) of 5α-reductase in prostate was identical in both groups, being 0.22 and 0.24 μM for HE- and HO-rats, respectively. (2) The mean 5α-reductase activity was significantly ( P < 0.001; n = 18) lower in prostate of HE- (11.1 ± 0.5 (SEM) pmol 5α-reduced metabolites mg protein −1· h −1) than HO-rats (13.9 ± 0.4). (3) The mean apparent K m of 3α(β)-HSDH was identical in HE- and HO-rats, being 3.7 and 4.3 μM, respectively. (4) The mean 3α(β)-HSDH activity was significantly ( P < 0.001; n = 20) lower in prostate of HE- (1.58 ± 0.05 (SEM) nmol 3α(β)-reduced metabolites · mg protein −1· h −1) than HO-rats (1.85 ± 0.05). (5) The mean 3α(β)-HSDH activity was significantly ( P < 0.001; n = 24) lower in BCLA of HE- (284 ± 9.6 (SEM) pmol 3α(β)-reduced metabolites · mg protein −1· h −1 than HO-rats (422 ± 18.7). (6) Besides prostate and BCLA, also the absolute as well as relative weights of the kidney were significantlky higher in HE- than HO-rats. (7) It will be discussed that despite various significant differences in androgen metabolism, other factors might be responsible for the organ weight differences of prostate, BCLA and kidney between HE- and HO-rats.

Sexual environment and molybdate: Two factors influencing the androgen-receptor quantification in prostate, bulbocavernosus/levator ami and heart muscle of male wistar rats

To improve the androgen-receptor quantification we studied the effect of molybdate (MoO 4 2−) on the androgen receptor (AR) in the heart muscle (HM), prostate (PR) and bulbocavernosus/levator ani muscle (BCLA) of male adult Wistar rats, which lived either under homosexual (HO-rats) or heterosexual (HE-rats) conditions. Receptor analysis was done in 100 000 X g·cytosol by agar-gel electrophoresis and Sephadex G25 gel filtration after incubating the organ homogenates of the 24 h castrated rats for 2 h at 0°C with methyltrienolone (R1881). The main findings are: (1) MoO 4 2− did not change the qualitative binding characteristics of the AR in the various organs of HE- and HO-rats, the binding affinity remained unaltered ( K d 1.1 nM). (2) The assayable AR concentration in HM of HO-rats, analyzed by agar-gel electrophoresis, increased significantly ( P < 0.0001) from 1.9 fmoles/mg protein in the absence of MoO 4 2− to 3.8 fmoles/mg protein in the presence of MoO 4 2−. Similar results were found for the AR concentration in the HM of HE-rats. The assayable AR concentration in PR and BCLA of HO-rats remained unaffected by MoO 4 2−. (3) Compared to HO-rats the assayable receptor concentrations in PR and BCLA of HE-rats were significantly lower ( P < 0.05 for PR, n = 9; P< 0.01 for BCLA, n = 7) in the absence of MoO 4 2− as analyzed by agar-gel electrophoresis; the means were 117 ± 22 (SEM) fmoles/mg protein for PR and 14 ± 1.1 (SEM) for BCLA. Adding MoO 4 2− to the buffer medium, the significantly ( P < 0.02 for PR, n = 9; P < 0.001 for BCLA, n = 7) higher amounts of assayable AR sites were nearly the same as in the HO-rats (PR: 224 ± 30; BCLA 24 ± 1.9). (4) Concerning the organ weights, no significant differences could be found between the heart weights of HO- and HE-rats. On the other hand, the weights of PR and BCLA of HO-rats were significantly lower than those of the HE-rats i.e. with regard to PR and BCLA in the absence of MoO 4 2− the organ weights correlated inversely with the assayable AR concentrations. The results indicate that the quantitative AR assay depends on the status of the rats (HE-versus HO-rats). Furthermore, MoO 4 2− does not alter the qualitative binding characteristics of the AR, but is under definite circumstances able to enhance markedly the amounts of bonding sites. This enhancement depends on the organ and/or the status of the rats which were used.

Recovery of free androgens in the rat prostate in vivo and in vitro after treatment with orally active testosterone undecanoate (TU).

Short term castrated rats were sacrificed at different time intervals after oral administration of tritium labeled TU. Blood and organs were collected and measured for total radioactivity uptake. At the time of peak values of radioactivity the in vivo metabolite pattern was investigated by thin layer chromatography. In vitro studies were performed in plasma, muscle and prostate cytosol. The radioactivity uptake into plasma and prostate in vivo reached a first maximum 2 1/2 h after oral administration of TU. A second peak appeared after 5 h in the prostate. While only 16% of the total plasma radioactivity appeared in the non esterified fraction, the tissues contained 69-71%. In plasma, the bulbocavernosus/levator ani muscle and in the skeletal muscle, free testosterone was the main unesterified androgen (14-28%). Prostate and seminal vesicles contained primarily 5 alpha-DHT (47 and 34%, respectively). Further metabolites were found in the fractions of 17 beta-hydroxy-5 alpha-androstanediols, epiandrosterone, androsterone, 4-androstenedione and 5 alpha-androstanedione. After incubation in vitro with TU, prostate and muscle cytosol contained significant amounts (39% and 17%, respectively) of free androgens. It was concluded that peripheral organs as well as the prostate itself are capable of cleaving the undecanoic ester and that the biological action of TU is exerted by unesterified androgens which occur in a pattern similar to that obtained after i.v. injection of free testosterone.

Androgen receptor translocation from cytosol of rat heart muscle, bulbocavernosus/levator ani muscle and prostate into heart muscle nuclei

Translocation of cytosolic androgen receptor of heart muscle (HM), bulbocavernosus/levator ani muscle (BCLA) and prostate (PR) into HM nuclei was studied in a cell-free system. Cytosol and nuclei were obtained from 24 h castrated male rats. The cytosolic androgen receptor was prelabelled with tritiated testosterone (T). After incubation with prelabelled cytosol, the highly purified HM nuclei were treated with 0.6 M NaCl and binding in the salt extractable fraction was analyzed by the charcoal adsorption method and by agargel electrophoresis. Furthermore, the receptor bound metabolites in cytosol and nuclei were analyzed by thin layer chromatography. The main results were as follows: 1. Highly purified HM nuclei were obtained, the purification being checked by electron microscopy and biochemical markers. 2. When incubating HM nuclei with T-labelled HM, BCLA or PR cytosol, a nuclear receptor binding was demonstrated by agargel electrophoresis. 3. No nuclear receptor binding was found using labelled plasma instead of organ cytosol. 4. The identity of cytosolic and nuclear receptor binding was indirectly shown by similarities in competition studies with unlabelled T, cyproterone acetate, and cortisol. Moreover, the metabolite pattern of receptor bound radioactivity was identical in cytosolic and nuclear fractions. The number of receptor bound labelled molecules found in HM nuclei by the charcoal adsorption technique after incubation with HM and PR cytosol were on average 49 and 652 per nucleus respectively. Compared to the receptor concentration in HM and PR cytosol, a 14.5- and 15.7-fold accumulation of receptor bound molecules in the incubated HM nuclei were found respectively. This study indicates that cytosolic androgen receptor of HM, BCLA and PR cytosol can be translocated into HM nuclei. The amount of translocated steroid receptor complex is dependent on the cytosolic receptor concentration.

Quantification of endogenous testosterone, 5α-dihydrotestosterone and 5α-androstane-3α, 17β-diol in subcellular fractions of the prostate, bulbocavernosus/levator ani muscle, skeletal muscle and heart muscle of the rat

Testosterone (T), 5α-androstan-17β-ol-3-one (dihydrotestosterone, DHT) and 5α-androstane-3α,17β-diol (3α-diol) were measured by radioimmunoassay (RIA) in the tissue homogenates, cytosols and nuclear fractions of the prostate (PR), bulbocavernosus/levator ani muscle (BCLA), skeletal muscle (musculus quadriceps femoris, SM) and heart muscle (HM) of adult male rats. The main results were: (a) In all three of the PR preparations the main metabolite found was DHT. T could not be detected in the cytosol and 3α-diol was absent in the nuclei, (b) The muscles contained predominantly T. Besides the homogenates DHT was found only in the nuclear fractions. 3α-diol could only be detected in the homogenates and HM-cytosol but not in the nuclei, (c) Comparing the various organs, a clear ranking, PR > BCLA > SM > HM, was found for DHT in the homogenates and similarly but less pronounced in the nuclear fractions, whereas T was generally higher in the muscle homogenates, cytosols and nuclear fractions than in the PR. These data are discussed with respect to the present knowledge of specific androgen accumulation and metabolism in the different organs.