Mitochondria isolated from Xenopus laevis embryos at various developmental stages show a good oxidative capacity and an acceptable respiratory control provided that certain requirements are fulfilled. The rates of respiration with pyruvate and Krebs' cycle intermediates, especially with citrate and isocitrate, are very low during cleavage stages and increase after gastrulation. Glutamate in the presence of malate is the only substrate to be readily oxidized during early development and its rate of oxidation decreases after gastrulation. These results, together with the altered sensitivity of embryonic mitochondria towards azide, support the view that the oxidative metabolism undergoes important changes around gastrulation and is associated with mitochondrial differentiation.

Age Factors↗

PubMed1982

Effects of alloxan and streptozotocin on calcium transport in isolated mouse liver mitochondria.

The effect of alloxan and streptozotocin on the fluxes of Ca2+ in isolated mouse liver mitochondria was studied with dual wave-length spectrophotometry, using antipyrylazo III as metallochromic indicator. Streptozotocin had no effect on Ca2+ uptake, whereas alloxan inhibited the initial rate and extent of Ca2+ influx in a way dependent on the duration of preincubation, and occurrence of Pi in the reaction mixture. A rapid release of Ca2+ followed upon addition of either FCCP or alloxan after the reaction had been started. When added to preloaded mitochondria, alloxan induced a concentration dependent release of Ca2+. The data suggest that alloxan induces an initial release of mitochondrial Ca2+, which is followed by inhibition of Ca2+ influx. The initial release may be due to uncoupler activity induced by alloxan, and the inhibition of Ca2+ influx may be a consequence of inhibited Pi transport.

Alloxan↗

PubMed1982

Changes in energy metabolism during the early development of Xenopus laevis.

Xenopus embryos at various development stages were incubated in the presence of labelled substrates and the 14CO2 production determined. From the rates of oxidation of glucose labelled in positions 1 and 6 and from that of radioactive acetate, pyruvate and glutamate, it was concluded that the Embden-Meyerhof pathway and the Krebs cycle are functional during early embryogenesis, but that their relative participation in the metabolic processes is limited and increases from gastrulation onwards. Early development is characterized by the predominance of the pentose cycle and the glutamate-aspartate cycle. Furthermore, it was shown that glutamate may be the main energy source up to gastrulation.

Acetates↗

PubMed1982

Effect of alloxan on phosphate transport in isolated mouse liver mitochondria: influence of pH, and differentiation between influx and efflux of phosphate.

The effect of alloxan on inorganic phosphate (Pi) transport in isolated mouse liver mitochondria was studied by swelling techniques. Mitochondria preincubated with alloxan exhibited inhibition of Pi uptake assessed by NH4-Pi, K+-ionophore and acetate/Pi exchange systems, and also inhibition of Pi efflux assessed by the K+-ionophore and FCCP1-ATP systems. The effect on Pi uptake was pH dependent. Swelling in the FCCP-ATP system in the presence of alloxan and NEM was unaffected by rotenone and cysteine but was blocked by oligomycin, whereas the swelling caused by mersalyl was unaffected by rotenone, blocked by oligomycin, and reversed by cysteine. Alloxan stimulated mitochondrial ATPase activity, this effect being blocked by oligomycin. These findings suggest that alloxan causes an irreversible and pH-dependent inhibition of Pi influx and efflux in isolated mouse liver mitochondria.

Adenosine Triphosphatases↗

PubMed1981

Reversal by acupuncture of cardiovascular depression induced with morphine during halothane anaesthesia in dogs.

The cardiovascular effects of morphine sulphate and/or acupuncture by means of electrocautery at Jen Chung (Go-26) were studied in 35 dogs. All animals were maintained under anaesthesia with halothane 0.75 per cent supplemented by the intravenous administration of succinylcholine to allow controlled ventilation during a two hour period of monitoring. Cardiac output, stroke volume, heart rate, mean arterial pressure, pulse pressure, central venous pressure, total peripheral resistance, [H+] (pH) PaCO2, PaO2 and base deficit were measured in each dog. Morphine 0.5 mg . kg-1, administered alone as a single bolus, significantly (P less than 0.05) decreased cardiac output, heart rate, mean arterial pressure, and significantly increased stroke volume and pulse pressure in dogs under halothane anaesthesia. Acupuncture by electrocautery alone induced a significant increase in cardiac output, stroke volume, heart rate, mean arterial pressure and pulse pressure with a significant decrease in total peripheral resistance following halothane. Acupuncture at Jen Chung (Go-26) for 10 minutes following the intravenous administration of morphine caused a significant increase in cardiac output, heart rate and mean arterial pressure with a significant decrease in central venous pressure and total peripheral resistance during halothane anaesthesia. The depressant effect of morphine on cardiac output, heart rate and mean arterial pressure in dogs under halothane anaesthesia appears to be reversed by acupuncture by electrocautery at Jen Chung (Go-26). Stimulation of this acupuncture locus could be helpful in resuscitating patients whose cardiovascular system is depressed by morphine and/or halothane anaesthesia.

Acupuncture Therapy↗

PubMed1981

Stress and age effects on catecholamines in normal subjects.

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Adult↗

PubMed1981

Pilocytic astrocytoma of the optic nerve with hemorrhage and extreme cystic degeneration.

Juvenile pilocytic astrocytoma of the optic nerve (glioma of childhood) usually grows slowly. Rapidly evolving proptosis is rare and reflects the accumulation of mucinous or hemorrhagic material within the tumor. Rapid proptosis is more common in those patients beyond the first two decades of life who have long-standing tumors. We studied a 26-year-old woman with rapid proptosis caused by a large blood-filled cyst in a pilocytic astrocytoma of the optic nerve. The cyst was surgically removed along with the intraorbital portion of the optic nerve.

Adult↗

PubMed1981

Effects of ouabain on spermatozoan function: a review.

The cardiac glycoside, ouabain, exerts its influence on spermatozoa by binding to and inhibiting Mg2+-activated Na+, K+-dependent ATPase that is located in the midpiece-tail membranes. Ouabain decreased intracellular potassium, increased intracellular sodium, and produced a biphasic and time-dependent effect on motility--stimulation at low concentrations and inhibition at high concentrations. The motility depression consisted of decreases in numbers of motile cells, percent progressive motility, beat frequency, and amplitude. Species differences and maturational age of the sperm cells were reflected in the degree of the ouabain effect and also the distribution of the ouabain-sensitive enzyme. The presence of this enzyme in spermatozoan membranes contributes significantly to regulation of sperm cell function through modulation of cationic fluxes which in "conventional" cell types influence their excitability.

Animals↗

PubMed1981

Inhibition by alloxan of mitochondrial anion transport.

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Alloxan↗

PubMed1981

Effect of alloxan on phosphate transport in isolated mouse liver mitochondria.

The swelling technique was used to study the transport of inorganic phosphate (Pi) in isolated mitochondria from mouse liver. Mitochondria preincubated with alloxan exhibited an early inhibition of Pi uptake, which was dependent both upon the concentration of alloxan and the duration of the reaction with alloxan. No significant inhibition was found with 1 mM alloxan, whereas 10 mM alloxan caused approximately 50 percent inhibition. Maximum inhibition was observed at 2 min with 10 mM alloxan, and at 10 min with 2.5 mM alloxan. Alloxan did not significantly affect the swelling of mitochondria preincubated with acetate, indicating that the inhibition by alloxan of Pi uptake is due to an action of the drug on the Pi carrier (Pi/OH-). The findings support our Pi-pH hypothesis for the development of alloxan diabetes.

Alloxan↗

PubMed1980

Sperm motility and calcium transport: a neurochemically controlled process.

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Acetylcholine↗

PubMed1980

Fine structural and histochemical studies on salivary glands of Peripatoides novae-zealandiae (Onychophora) with special reference to acid phosphatase distribution.

The Onychophora feed on small arthropods and produce saliva when ingesting prey. Although saliva undoubtedly helps to liquefy the food its constituents have not yet been fully described. The salivary glands, two long tubes of glandularepithelium, are known to secrete a powerful protease, however, besides other enzymes and mucus. In Peripatoides novae-zealandiae there are protein-secreting cells of three types, referred to here as columnar, cuboidal and modified cells, and mucus cells. The anterior two-thirds of the gland show most cell diversity, while the posterior regionconsists mainly of columnar cells. These are the most numerous elements overall and they probably secrete salivary protease. In thick resin sections the granules of all protein-secreting cells stain strongly with methylene blue. Those of columnar cells are markedly uneven in size and accumulate distally, eventually filling the cytoplasm. More proximal Golgi regions may be discernible. Mucus cells are all of one type and their secretion droplets are stained lightly by methylene blue. The electron microscope shows that distal microvilli, desmosomes and septate junctions are common to all gland cells. In columnar cells, secretory material is contributed by Golgi complexes and by rough endoplasmic reticulum. Early secretory vacuoles containing dense material are seen in the concavity of Golgi regions. They are precursors to larger condensing vacuoles whose contents have a more flocculent appearance, and which may attain 3--4 micrometers in diameter. These evolve into secretory granules, usually of uneven texture, which are up to 2.5 micrometers in diameter. Histochemical tests for acid phosphatase show moderate amounts of enzyme throughout the gland. In whole mounts and sections the strongest reaction is in a band of cuboidal cells along the anterior median border. Columnar cells show a diffuse cytoplasmic reaction towards the base and sometimes distal to the nucleus, and mucus cells may also react strongly round the nucleus. Cytoplasm near the lumen shows little reaction. The secretory granules do not appear to contain active enzyme. Under the electron microscope a positive reaction for acid phosphatase is seen in lysosomal derivatives near the base and lateral periphery of gland cells. These bodies are probably outophagic vacuoles and they may contain membranous whorls and possibly old secretion granules. Acid phosphatase is involved also in the eleboration of new secretory granules in both columnar and mucus cells. Dense reaction products is found in a system of interconnected tubules and cisternae near the innermost face of the Golgi complex, which is interpreted as GERL. Acid phosphatase is present in the peripheral zone of adjacent early secretory vacuoles, and interconnections occur between GERL and secretory vacuoles. It is suggested that GERL tubules containing the enzyme may fuse with early secretory vacuoles and release acid phosphatase at their periphery...

Acid Phosphatase↗

PubMed1980

Effects of unilateral torsion of the spermatic cord on the contralateral testis in human and guinea pig.

The fine structure of the contralateral, so-called unaffected, testis of two of three patients with unilateral testicular torsion revealed varying degrees of abnormalities, apparently related to the time course of the condition. In one patient (H-87) with unilateral torsion of 16 days duration, the contralateral testis revealed various morphological abnormalities. These included abnormal nuclear condensation in spermatids, disappearance of the inner component of the basal lamina, degeneration of the germinal epithelium, and "intermixing" of germinal epithelial cells with peritubular components. In the other patient (H-109) with severe atrophy of one testis as a result of torsion, the contralateral testis revealed abnormalities which included spermatids with degenerating heads and tails within the Sertoli cell cytoplasm near the basal lamina and peritubular thickening accompanied by a greater than usual number of Leydig cells. In guinea pigs with experimentally induced unilateral torsion, abnormal spermatid development was seen in the contralateral testis of those animals in which the affected testis was severely damaged. Moreover, the Sertoli cells exhibited a high degree of phagocytic activity. Fewer abnormal spermatids in the spermatogonial compartment were found in the contralateral testis of the animals which had only moderately altered histology of the affected testis. No fine structural change was noted in the contralateral testis of control or sham operated animals or in those which displayed only minimal damage in the affected testis. This study suggests that unilateral torsion of the spermatic cord resulting in moderate to severe damage to the affected testis may be associated with morphological abnormalities in the contralateral testis.

Adolescent↗