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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A method is described to measure the intracellular content of pyruvate and lactate in epididymal adipose tissue of the rat. The intracellular pyruvate concentration was approx. 330mum. Intracellular pyruvate contents and the rates of pyruvate output were increased when NNN'N'-tetramethyl-p-phenylenediamine was added, and decreased in the presence of alanine. Insulin addition caused an increase in intracellular pyruvate contents only at the earlier time-period studied (1.5min as against 20min). Pyruvate dehydrogenase activity was increased in adipose tissue incubated in vitro with insulin. This increase occurred subsequent to the rise in the intracellular pyruvate content induced by insulin addition. The possible physiological implications are discussed.
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PMID:Effect of insulin on pyruvate metabolism in epididymal adipose tissue of the rat. Correlation of intracellular pyruvate contents and pyruvate dehydrogenase activity. 476 61

Plasma membranes from bovine epididymal spermatozoa possess both cAMP-independent and cAMP-dependent protein kinase activity. With the synthetic peptide, Leu-Arg-Arg-Ala-Ser-Leu-Gly as substrate, the basal activity of the membrane-associated protein kinase(s) was 0.1 nmol phosphate incorporated X min X mg protein. In the presence of 5 microM cAMP, the apparent activity was increased about twofold. The addition of Nonidet P-40 (0.05%) to the assay mixture increased protein kinase activity to 0.4 and 4.0 nmol phosphate incorporated X min X mg protein in the absence or presence of 5 microM cAMP, respectively. Both isozymes of the cAMP-dependent protein kinase were detected in detergent-solubilized membranes but 95% of the activity appeared as a Type II form based on DEAE-Sephacel chromatography. Several polypeptide components of the plasma membrane served as substrates for membrane-associated cAMP-dependent protein kinases, in vitro. In the absence of detergent, two cAMP-dependent phosphoproteins of 41,000 Mr and 60,000 Mr were detected by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. When 0.05% Nonidet P-40 was included in the assay mixture, a cAMP-dependent phosphoprotein of 43,000 Mr appeared. Two-dimensional polyacrylamide gel electrophoresis of membranes phosphorylated in the presence of 5 microM and 0.05% Nonidet P-40 revealed phosphoproteins of the following molecular weights/isoelectric points: 56,000/6.7, 56,000/6.9, 51,000/6.2, 42,000/5.9, 42,000/6.0, 38,000/6.1, 38,000/6.4, 14,000/7.2, 12,000/7.4 and a train of five polypeptides appearing at 14,000/5.4-6.0.
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PMID:Protein phosphorylation of plasma membranes from bovine epididymal spermatozoa. 608 45

Protein synthesis and degradation were measured simultaneously in epididymal fat pads of rats by use of the incorporation of [14C]phenylalanine into protein and the sum of net protein breakdown and protein synthesis, respectively. Neither glucose nor insulin altered protein synthesis, but together they promoted this process; pyruvate could be substituted for glucose. Separately, glucose or insulin diminished proteolysis, and these effects were additive. In the presence of glucose and insulin, leucine, alanine, glutamine, glutamate, and aspartate lowered protein degradation to varying degrees but did not alter protein synthesis. Glutamate, but not leucine or alanine, was inhibitory without glucose and insulin present. When aminooxyacetic acid was provided to decrease the rate of transamination of amino acids, the inhibitory effects of leucine, alanine, and aspartate, but not of glutamate, appeared to be diminished. alpha-Ketoglutarate, but neither alpha-ketoisocaproate nor pyruvate, could diminish proteolysis. Inhibition of proteolysis was associated with a higher tissue content of glutamate and a greater production of glutamate and glutamine. These results suggest that glutamate itself may inhibit proteolysis in adipose tissue and mediate, at least in part, the effects of other amino acids.
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PMID:Regulation of protein turnover by glucose, insulin, and amino acids in adipose tissue. 614 13

A highly potent agonist of LHRH, [6-D-(2-naphthyl)-alanine]-LHRH, was administered chronically for 12 weeks to adult male rats by repetitive implantation of pellets, and its effects upon mating, fertility, and reproductive organ weights have been evaluated. Although significant declines in testicular (P less than 0.001) and epididymidal (P less than 0.001) weights were achieved, no effects on seminal vesicles, prostate, or pituitary weights were observed. After 12 weeks of continuous treatment, three of six agonist-treated rats were still successfully impregnating females. The decline in successful impregnation appeared to be related to the observed reduction in testicular spermatogenesis and in numbers of epididymal spermatozoa. The drug effects appeared reversible, as all six of the agonist-treated rats were fertile by the fifth week after cessation of treatment. Plasma levels of testosterone were markedly elevated immediately after implantation of each pellet and consistently, but not significantly, lowered during the inter-implantation periods. These observations, and the lack of effect on accessory organ weights, are consistent with the maintenance of libido in these treated rats. This is the second demonstration of a selective inhibition of spermatogenesis in the absence of a marked decline in gonadal steroidogenesis with this agent. As in the first demonstration using twice weekly injections, the degree of inhibition of spermatogenesis was insufficient to abolish fertility in the treated male rats.
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PMID:Inability of continuous long-term administration of D-Nal(2)6-LHRH to abolish fertility in male rats. 622 58

Soft tissue injury to one hindlimb of rats was used to test the response to trauma of metabolism in epididymal fat pads. Degradation of [1-14)C]leucine was lower on day 2 after injury, but not on days 1 or 3, whether or not glucose or insulin were provided. Although trauma did not affect the basal rate of release of 14CO2, lactate or pyruvate from fat pads incubated with [U-14C] glucose, the stimulation by insulin of these processes was smaller in fat pads of 2 day traumatized than of normal animals. These results suggest that trauma due to injury may decrease the capacity for utilization of leucine and glucose by adipose tissue. Release of alanine, glutamine and glutamate by fat pads incubated with leucine was also lower on day 2. This decreased efflux could not be accounted for by changes in net protein breakdown or in pyruvate availability and probably reflected their reduced de novo synthesis due to the diminished release of nitrogen from leucine.
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PMID:Metabolism of amino acids, protein and glucose in fat pads of traumatized rats. 637 55

Rabbit sperm pyruvate kinase remains bound to the cell structure of hypotonically treated mature rabbit epididymal spermatozoa (HTRES). It displays kinetic behavior very similar to that of rabbit muscle pyruvate kinase with regard to KM values for substrates, activation by monovalent and divalent cations, inhibition by phenylalanine which is reversed by alanine, and lack of activation by fructose-1,6-biphosphate. The flagellar ATPase also remains bound to the cell structure of HTRES, whose motility may be reactivated by a source of ATP. It requires Mg+2 for activity; the KM for both ATP and MG+2 is 0.2 mM, implying that MgATP is the substrate. The ATPase activity is not inhibited by ouabain, oligomycin, or vanadate, which also do not affect reconstituted motility, and is not affected by cyclic AMP in the presence of an inhibitor of phosphodiesterase. The activities of pyruvate kinase and the flagellar ATPase in a given preparation of HTRES are comparable. Rabbit spermatozoa have a metabolic strategy which is very similar to muscle cells. This suggests that the major use of the sperm cell's metabolic machinery is maintenance of energy for the contractile work of motility and that only minor amounts of metabolic energy appear to be consumed in other reactions, including those involved in fertilization.
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PMID:Properties of pyruvate kinase and flagellar ATPase in rabbit spermatozoa: relation to metabolic strategy of the sperm cell. 644 94

The effect of amino acids on insulin responsiveness in epididymal adipose tissue was examined. It was found that insulin-stimulated glucose oxidation in fat cells was significantly inhibited by glycine, alanine, valine, leucine, isoleucine, cysteine, methionine, lysine, phenylalanine, and proline. The effect of insulin on glucose incorporation into triglyceride is also severely diminished by these amino acids. In addition, alanine reduced the incorporation of precursors ([U-14C]glucose or [1-14C]palmitate) into triglyceride both in vitro and in vivo. The Ki values of alanine were 0.4 and 0.5 mM toward the precursors of glucose and palmitate, respectively. The mechanism of reduction of insulin responsiveness in rat adipose tissue is discussed on the basis of these results.
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PMID:Effect of amino acids on insulin-stimulated glucose metabolism in fat cells. 701 47

The substrate specificity of rat testicular and epididymal peptidase was investigated using chromogenic substrates, D. L-alanine-, L-arginine-, gamma-N-L-glutamine-, L-leucine-, D. L-methionine-, alpha-N-benzoyl-D. L-arginine-, and N-benzoyl-L-leucine-beta-naphthylamide. The histochemical distribution of peptidase activity demonstrated with these substrates was also investigated in the testis and epididymis. L-Arginine-beta-raphthylamide (Arg-beta-NA) and gamma-N-L-glutamine-beta-naphthylamide (Glu-beta-NA) were mostly hydrolyzed in the testis and epididymis, respectively. Histologically, the activity using Arg-beta-NA as substrate (aminopeptidase B) appeared in both the cytoplasms and nuclei of interstitial cells and spermatogonia and the heads of spermatozoa, while activity using other substrates was found only in the cytoplasms of cells in the germinal epithelium. In the epididymis, strong reaction with Glu-beta-NA (gamma-glutamyl transpeptidase) was found in the apical part of the epithelial cells and in the heads of spermatozoa. Neither alpha-N-benzoyl-L-arginine- nor N-benzoyl-L-leucine-beta-naphthylamide was utilized in either the testis or the epididymis.
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PMID:Substrate specificity and histochemical distribution of aminopeptidase in rat testis and epididymis. 705 30

The effect of chymotrypsin inhibitors and substrates on the human sperm acrosome reaction stimulated by the human zonae pellucidae or follicular fluid were evaluated. Motile spermatozoa, selected by a Percoll gradient, were incubated at 1 x 10(7) cells/ml, 37 degrees C, and 5% CO2. After 4.5 hr, the chymotrypsin inhibitor TPCK (N-Tosyl-L-Phenylalanine-Chloromethyl Ketone) or the substrate ATEE (N-Acetyl-L-Tyrosine Ethyl Ester) were added for 30 min. Then, four oocytes were added and the percentage of acrosome-reacted spermatozoa on the zona was determined. TPCK and ATEE inhibited the zona pellucida-induced acrosome reaction. The chymotrypsin inhibitors TPCK and chymostatin and the chymotrypsin substrates ATEE, BTEE (N-Benzoyl-L-Tyrosine Ethyl Ester), Succinyl-Ala-Ala-Phe-7-Amido-4-Methyl-Coumarin (Suc-Ala-Ala-Phe-AMC), and Succinyl-Leu-Leu-Val-Tyr-7-Amido-4-Methyl-Coumarin (Suc-Leu-Leu-Val-Tyr-AMC) inhibited the human follicular fluid-induced acrosome reaction. Sperm extracts exhibited hydrolytic activity toward Suc-Ala-Ala-Phe-AMC and Suc-Leu-Leu-Val-Tyr-AMC. This enzyme activity was abolished by TPCK and chymostatin, was independent of Ca2+, and was not modified by 1,10 phenanthroline. In addition, the activity was present in the supernatant after the acrosome reaction was induced with calcium ionophore and in epididymal spermatozoa recovered from the cauda region. Electron microscopic observations indicated that the inhibitors prevented the membrane events of the acrosome reaction. These data suggest an association between human spermatozoa and chymotrypsin-like activity with a possible role in the acrosome reaction.
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PMID:Evidences for the presence of chymotrypsin-like activity in human spermatozoa with a role in the acrosome reaction. 808 Jun 52

AH-9 is an acylhydrazine compound with hypoglycemic effects in normal mice, alloxan-induced diabetic mice and spontaneously diabetic KK mice. In terms of equi-molar doses (0.3 mmol/kg po), AH-9 was found to be more potent than phenfornin and glicalazide (diamicron) in normal mice. Insulin resistance was shown to be improved in spontaneously diabetic KK mice and hydrocortisone-induced insulin resistant mice after treatment with AH-9. The LD 50 of AH-9 given orally to mice was found to be 956 mg/kg (about 18 times its effective dose). Studies on the hypoglycemic mechanism of AH-9 (insulin release, insulin receptor and post-receptor) showed that AH-9 did not influence serum insulin levels in mice. But, in in vivo experiments, AH-9 appeared to promote the capacity and affinity of insulin receptors in mouse liver plasma membranes. AH-9 was also found to antagonize the elevation of blood glucose level and liver glycogen content caused by alanine injection. AH-9 was shown to enhance the conversion of U-14C-glucose to 14CO2 in mouse epididymal fat tissue in vitro. According to the above results, the hypoglycemic action of AH-9 might be due to: 1) increasing the capacity and affinity of insulin receptors; 2) directly enhancing glucose aerobic oxidation; and 3) inhibiting gluconeogenesis.
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PMID:[The hypoglycemic effect of AH-9]. 816 1


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