Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have developed radiometric assays for small quantities of glycerol, glucose and glycogen, based on a technique described by Thorner and Paulus (1971, J. Biol. Chem. 246, 3885-3894) for the measurement of glycerokinase activity. In the glycerol assay, glycerol is phosphorylated with [32P]ATP and glycerokinase, residual [32P]ATP is hydrolyzed by heating in acid, and free [32P]phosphate is removed by precipitation with ammonium molybdate and triethylamine. Standard dose-response curves were linear from 50 to 3000 pmol glycerol with less than 3% SD in triplicate measurements. Of the substances tested for interference, only dihydroxyacetone gave a slight false positive signal at high concentration. When used to measure glycerol concentrations in serum and in media from incubated adipose tissue, the radiometric glycerol assay correlated well with a commonly used spectrophotometric assay. The radiometric glucose assay is similar to the glycerol assay, except that glucokinase is used instead of glycerokinase. Dose response was linear from 5 to 3000 pmol glucose with less than 3% SD in triplicate measurements. Glucosamine and N-acetylglucosamine gave false positive signals when equimolar to glucose. When glucose concentrations in serum were measured, the radiometric glucose assay agreed well with hexokinase/glucose-6-phosphate dehydrogenase (H/GDH)-based and glucose oxidase/H2O2-based glucose assays. The radiometric method for glycogen measurement incorporates previously described isolation and digestion techniques, followed by the radiometric assay of free glucose. When used to measure glycogen in mouse epididymal fat pads, the radiometric glycogen assay correlated well with the H/GDH-based glycogen assay. All three radiometric assays offer several practical advantages over spectral assays.
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PMID:Radiometric assays for glycerol, glucose, and glycogen. 281 33

Rat sperm from the cauda epididymis exhibit increased motility, longevity, and a distinct circular pattern of flagellar curvature in response to 5 mM procaine-HCl or 0.1 mM 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate (TMB-8), reagents that are thought to play a role in the immobilization of free cellular calcium. Triton X-100-extracted sperm models will exhibit the same pattern of motility and curvature as procaine- or TMB-8-activated cells, but only when calcium is removed by a strong chelating agent, and in the presence of cAMP (3 microM). Demembranated sperm models produced from epididymal rat sperm are quiescent unless cAMP is added. In these sperm models, the presence or absence of free calcium mediates a transition in flagellar curvature. The increased activity of the procaine-treated intact cells was not accompanied by a change in cellular ATP content, nor was ATP availability the limiting factor in the quiescent sperm. Therefore, the increased motility produced by procaine is probably mediated by a fall in free intracellular Ca2+ accompanied by a rise in cAMP. Our finding that calcium controls the curvature of sperm flagella may explain altered patterns of flagellar beating, such as the hyperactivated motility that sperm exhibit in the female reproductive tract.
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PMID:Regulation of activation state and flagellar wave form in epididymal rat sperm: evidence for the involvement of both Ca2+ and cAMP. 282 20

Gossypol administered orally to male rats at a daily dose of 20 mg/kg body weight for 62 days caused infertility. There were changes in the epididymal epithelium and the sperm were severely damaged and immotile. The sperm head was often detached; other defects were abnormal mitochondria, absence of plasma membranes and axonemal and accessory fibres and a lower oxygen uptake. To study the effect of gossypol on the motor apparatus of sperm, ram sperm were demembranated with the detergent, Triton-X-100. Such sperm models can normally be reactivated with ATP but gossypol (2.5-12.5 microM) decreased reactivation and must have a direct effect on the axoneme. Gossypol also inhibited ram sperm adenyl cyclase which is essential for maintaining high levels of cAMP in sperm and, in turn, motility. Ram sperm adenyl cyclase required Mn2+ for activity and high Mn2+ concentrations protected the enzyme from gossypol inhibition. Electron spin resonance studies proved that gossypol chelated Mn2+ with the formation of a 2:1 complex.
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PMID:Studies of the mechanism of action of gossypol as a male antifertility agent. 283 27

Efficiency of substrates for cholesterol esterase (EC 3.1.1.13) assay, and regulation of the activity were investigated in rat epididymal adipose tissue. The activity in the supernatant was activated by cyclic AMP-dependent protein kinase, cyclic AMP, ATP and Mg2+, both with micellar and liposomal substrates. However, the micellar substrate was more suitable for the assay than the liposomal with respect to Vmax and Km. Thus, the micellar substrate was employed. Pretreatment of the supernatant with exogenous cyclic AMP-dependent protein kinase enhanced the activity dose dependently, whereas that with cyclic AMP decreased the activity slightly. The cyclic AMP-dependent protein kinase activity in the assay mixture was within the range which can cause changes in cholesterol esterase activity. These results suggest that the amount of cyclic AMP-dependent protein kinase, rather than the cyclic AMP level, plays an important role in the regulation of cholesterol esterase in tissues with a high cholesterol esterase activity relative to the kinase activity, such as in adipose tissue.
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PMID:Studies on cholesterol esterase in rat adipose tissue: comparison of substrates and regulation of the activity. 284 84

Adrenergic and purinergic compounds contract the longitudinal muscles of the rat vas deferens. Whereas ATP and related purinergic analogs produced contractions of greater magnitude in the prostatic half as compared to that of the epididymal end, the magnitude of the alpha 1-adrenoceptor-induced responses was larger in the epididymal than in the prostatic half of the rat ductus. Chemical sympathectomy following a 48 hr 6-hydroxydopamine-treatment (6-OHDA) caused a leftward displacement of the concentration-response curves for adrenergic and purinergic drugs, this effect being more evident in the prostatic segment. Sympathectomy caused a significant increase in the maximal response induced by ATP and adrenergic compounds which was more evident in the prostatic half of the rat ductus. The denervation-induced supersensitivity was stimulus-specific since angiotensin II and acetylcholine showed no significant change in potency. In the case of bradykinin, there was a manifest increase in the maximal response of the prostatic segment of the ductus of the chemically denervated tissues. In addition, denervation also caused an increase in the potency of prazosin and phentolamine as alpha 1-adrenoceptor blocking agents; denervation did not change the potency of yohimbine as an alpha 2-adrenoceptor blocker.
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PMID:Purinergic supersensitivity following sympathectomy adds further support to co-transmission in the rat vas deferens. 285 33

The photoaffinity analog [32P]8-N3 cAMP (8-azido adenosine 3',5'-monophosphate was used to analyze the membrane sidedness of rat sperm cAMP binding proteins during epididymal maturation. Evidence is presented here which supports the hypothesis that 35-45% of the regulatory subunits of the Type I and Type II cAMP-dependent protein kinases are readily available to externally added cyclic nucleotide. It was observed by sodium dodecyl sulfate gel electrophoresis (SDS-PAGE) and autoradiography that only two rat sperm proteins (Mr = 49K and 55K) were photolabeled which comigrated on gels with partially purified Type I and Type II regulatory subunits, respectively. Both of these photolabeled epididymal sperm proteins were saturated at physiological titers of [32P]8-N3cAMP and photoincorporation of [32P]8-N3 cAMP was specific since other SDS-resolvable sperm proteins did not photoincorporate the analog. Caput and cauda sperm protein photoincorporation could be effectively blocked by low levels of cAMP, but not by cGMP, ATP or GTP. Sperm epididymal maturation coincided with changes in the cAMP-dependent protein kinase subunits since cauda sperm contained more available Type II than did caput sperm. A subcellular analysis of cAMP-dependent protein kinase regulatory subunit in head and tail fractions was done for caput and cauda sperm and demonstrated that the tail fractions showed more photo-labeling of both Type I and II regulatory subunits than did the head fractions.
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PMID:A study of rat epididymal sperm adenosine 3',5'-monophosphate-dependent protein kinases: maturation differences and cellular location. 298 32

Flagellar movement of golden hamster spermatozoa obtained from the testis and the caput and cauda epididymides was observed by a light microscope while holding them at their heads with a micropipette. Flagellar movement of capacitated spermatozoa and of reactivated spermatozoa demembranated with Triton X-100 was also observed. Testicular and caput epididymal spermatozoa showed weak movement in Tyrode's solution, whereas cauda epididymal spermatozoa showed vigorous movement. The flagellar bends of the cauda epididymal spermatozoa were almost planar. Capacitated spermatozoa moved with waves of a large amplitude. Demembranated spermatozoa reactivated with ATP only had a latent period before the initiation of flagellar movement, and beat at low frequency, whereas demembranated spermatozoa reactivated with both ATP and cAMP began to move immediately at high frequency. Thrust and hydrodynamic power output were calculated using the parameters for the typical waveforms of cauda epididymal spermatozoa before and after capacitation. The possible role of the large amplitude beat in capacitated spermatozoa is discussed. A comparison of the 'principal' and 'reverse' bends in golden hamster sperm flagella as defined by Woolley (1977) with those in sea urchin sperm flagella suggests that the so-called 'principal' bend in golden hamster sperm flagella corresponds to the reverse bend in sea urchin sperm flagella and vice versa.
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PMID:A quantitative description of flagellar movement in golden hamster spermatozoa. 298 7

Phosphatidyl inositol has been found to inhibit strongly the activity of a cyclic AMP-independent protein kinase located on the external surface of goat epididymal intact spermatozoa. Phosphatidyl inositol at a concentration as low as 10 micrograms/ml inhibited nearly 50% of the ecto-kinase activity for the phosphorylation of the exogenous protein substrate: casein. Phosphatidyl ethanolamine at a relatively high concentration (125 micrograms/ml) inhibited slightly (approx 25%) the activity of the enzyme whereas other phospholipids: phosphatidyl serine and choline, diacyl glycerol, phosphatidic acid and myo-inositol-2-phosphate had no appreciable effect on the kinase activity. Phosphatidyl inositol has also served as a potent inhibitor of the phosphorylation of sperm ecto-phosphoproteins by the endogenous kinase activity of intact spermatozoa. By thin layer chromatography it has been shown that the observed inhibitory effect of the phospholipid was not due to any impurities or degraded products of phosphatidyl inositol. Phosphatidyl inositol inhibited the kinase activity noncompetitively with respect to casein and Mg2+ but uncompetitively with respect to ATP. The results raised the possibility that phosphatidyl inositol-mediated high affinity inhibition of protein kinase(s), may constitute a novel mechanism for the regulatory actins of the phospholipid in mammalian cells.
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PMID:Phosphatidyl inositol inhibition of a sperm cyclic AMP-independent protein kinase. 303 78

Verapamil (3 X 10(-6)-3 X 10(-5) M) enhanced the twitch contractions of the epididymal and prostatic portions of vas deferens stimulated at 0.1 Hz. This verapamil effect was essentially similar to those of diltiazem, D-600 and Bay K 8644. However, when stimulation at 2 Hz was used verapamil (3 X 10(-5) M) attenuated the contractions of the epididymal portion by half but still augmented those of the prostatic portion. Verapamil enhanced the reserpine- and prazosin-resistant component of the stimulation-induced contractions of both portions of the vas deferens. Yohimbine augmented the twitch response but attenuated the verapamil-augmented response. Verapamil did not augment norepinephrine- or tyramine-induced contractions whereas it augmented ATP-induced contractions of the prostatic portion but not of the epididymal portion. Verapamil increased the stimulation-evoked 3H-efflux from the vas deferens labelled with [3H]norepinephrine. It is suggested that verapamil augments non-adrenergic responses of both portions of the vas deferens by acting as a Ca agonist on the prejunctional site to increase the release of co-transmitter, or by acting on the postjunctional site to enhance the action of the substance released. Its effect in augmenting norepinephrine release is concluded not to contribute to the potentiating action.
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PMID:Verapamil enhances the non-adrenergic twitch response of rat vas deferens. 311 86

Calcium accumulation by ram sperm in the presence of 3.0 microM ionophore A23187 increased greatly when the pH of the medium was raised from 7.5 to 8.5. The increase in calcium uptake was remarkable between pH 7.5 and 8.0 and was paralleled by increased oxygen consumption. There was extensive vesiculation of the plasma membrane and membranes of the acrosome and postnuclear cap of ram sperm incubated with the ionophore and calcium at pH 8.0. The mitochondria of the midpiece contained pale and expanded cristae similar to ATP-deprived mitochondria in the "condensed" configuration. Such changes were not observed in ram sperm incubated under similar conditions at pH 7.0. The ionophore-induced calcium and oxygen uptake of cauda and caput epididymal boar sperm also increased with increased pH, but the effect commenced at a lower pH. Control cauda epididymal boar sperm (i.e., without ionophore) had higher oxygen uptake, glucose breakdown, and lactic acid production than caput sperm. The influence of pH on the operation of the membrane calcium pumps between ram boar sperm indicates species differences.
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PMID:Calcium uptake, respiration, and ultrastructure of sperm exposed to ionophore A23187. 312 77


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