Protein synthesis stimulation in rat liver by chloroquine

Riassunto L'inoculazione endoperitoneale di Clorochina, a dosi comprese tra 15 e 45 mg/kg di peso corporeo determina una stimolazione precoce delle sintesi proteiche nel fegato di ratto. Questa azione non é correlata ad un aumento della sintesi di RNA, né appare conseguente ad una stimolazione corticosurrenalica. L'effetto osservato é brevemente discusso sulla base delle note interazioni tra lisosomi e Clorochina.     

Time-dependence of estradiol effects on protein synthesis in the rat neurohypophysis.

The incorporation of 3H-leucine into neurohypophyseal proteins was measured in vitro, 24 h after the administration of a single dose of estradiol (0.3 mug) to castrated female rats. Estradiol treatment caused a significant increase of 3H-leucine incorporation into proteins of the posterior lobe. The effects of estradiol depended largely upon time injection. Rats injected at 06.00 h, i.e., at the end of the dark period exhibited a 74% increase in protein synthesis, whereas rat injected at 14.00 h, i.e., at the middle of the light period only showed a 30% of increase.     

The site of 25-hydroxycholecalciferol stimulated protein synthesis in the rat kidney

Summary Autoradiographs of the kidneys of rachitic rats dosed in vivo with 250 pmoles 25-hydroxycholecaliferol (25-OHD₃) and³H-leucine showed increased grain counts in portions of proximal renal tubules. On incubation of kidney slices the synthesis of only 1 cytosol protein was found to be stimulated by the steroid. On disc gel electrophoresis it had the characteristics of renal calcium binding protein.     

Protein synthesis in isolated,beating rat atria

Zusammenfassung Untersuchungen über die Proteinsynthese am isolierten, spontan schlagenden Rattenherzvorhof ergeben einen linearen Syntheseverlauf während mehrerer Stunden bei relativ normalem Energieverbrauch des Gewebes. Die Einbaugeschwindigkeit des Leuzins in das Gesamtprotein des Vorhofs ist höher als bei anderen untersuchten Geweben.

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Recipient of a Research Career Development Award No. 1-K3-HE-17, 885, from the U.S. Public Health Service.     

Protein synthesis inhibition induced by dimethylnitrosamine and diethylnitrosamine on isolated rat hepatocytes

Summary Time- and dose-dependent protein synthesis inhibition takes place following exposure to high doses of dimethylnitrosamine (DMN) or diethylnitrosamine (DENA) in isolated rat hepatocytes. The ability of DENA to depress protein synthesis is 5-fold higher than that of DMN. Cells inhibited by 60 min exposure to DMN or DENA, and then incubated in a nitrosamine-free medium, regain their initial rate of protein synthesis. This recovery is faster and more complete for DENA-treated cells.     

Inhibition of DNA synthesis in concanavalin A stimulated rat lymph node cells by serum from arthritic rats

Summary Serum from adjuvant arthritic rats inhibits the mitogenic response of rat lymph node cells to concanavalin A, leaving unaffected the response to phytohemagglutinin. This activity is already evident 4 days after adjuvant administration and persists for at least 28 days.     

Effect of trypsin on phytohemagglutinin stimulated DNA synthesis in rat spleen cell cultures

Résumé On a étudié l'action de la phytohémagglutinine (PHA) sur la stimulation de l'incorporation de thymidine tritiée à la DNA de cellules spléniques de rats, en cultures à court terme. Il a été possible de stimuler la synthèse de la DNA dans ce type de cultures au moyen de la trypsinisation des cellules dispersées avant l'addition de la PHA. Les variations relativement faibles observées dans ce type d'essai vont faciliter les études des mécanismes cellulaires et biochimiques associés à la stimulation par la PHA.     

Differences in luteinizing hormone release stimulated in rat anterior pituitary cells by leukotriene C4 and by gonadotropin-releasing hormone in vitro

Continuous administration of leukotriene C4 (LTC4, 10(-10) M) to superfused rat anterior pituitary cells increased LH release for 40 min only, whereas in a parallel experiment gonadotropin-releasing hormone (GnRH, 10(-9) M) evoked a continuous increase in hormone secretion. In contrast to GnRH, LTC4 did not desensitize rat anterior pituitary cells. The secretory action resulting from the administration of LTC4 (10(-10) M) was abolished for 40 min after previous stimulation. The results documented the dual action of LTC4 on LH exocytosis.     

Differences in luteinizing hormone release stimulated in rat anterior pituitary cells by leukotriene C4 and by gonadotropin-releasing hormone in vitro

Summary Continuous administration of leukotriene C₄ (LTC₄, 10^–10 M) to superfused rat anterior pituitary cells increased LH release for 40 min only, whereas in a parallel experiment gonadotropin-releasing hormone (GnRH, 10^–9 M) evoked a continuous increase in hormone secretion. In contrast to GnRH, LTC₄ did not desensitize rat anterior pituitary cells. The secretory action resulting from the administration of LTC₄ (10^–10 M) was abolished for 40 min after previous stimulation. The results documented the dual action of LTC₄ on LH exocytosis.     

Protein synthesis inhibition induced by dimethylnitrosamine and diethylnitrosamine on isolated rat hepatocytes.

Time- and dose-dependent protein synthesis inhibition takes place following exposure to high doses of dimethylnitrosamine (DMN) or diethylnitrosamine (DENA) in isolated rat hepatocytes. The ability of DENA to depress protein synthesis is 5-fold higher than that of DMN. Cells inhibited by 60 min exposure to DMN or DENA, and then incubated in a nitrosamine-free medium, regain their initial rate of protein synthesis. This recovery is faster and more complete for DENA-treated cells.     

Inhibition of DNA synthesis in concanavalin A stimulated rat lymph node cells by serum from arthritic rats.

Serum from adjuvant arthritic rats inhibits the mitogenic response of rat lymph node cells to concanavalin A, leaving unaffected the response to phytohemagglutinin. This activity is already evident 4 days after adjuvant administration and persists for at least 28 days.     

Stimulation of histamine synthesis in rat mast cells by compound 48/80 in vitro

The histamine content of rat peritoneal fluid cells is doubled within 20 min by 0.5 microgram/ml of compound 48/80. Histamine catabolism inhibitors do not reproduce this effect; cells pre-incubated with alpha-fluoromethylhistidine are unresponsive to compound 48/80 which therefore activates pre-formed histidine decarboxylase rather than 'inducing' it. Non-mast cells showed no change after treatment with compound 48/80.     

Stimulation of histamine synthesis in rat mast cells by compound 48/80 in vitro

Summary The histamine content of rat peritoneal fluid cells is doubled within 20 min by 0.5 g/ml of compound 48/80. Histamine catabolism inhibitors do not reproduce this effect; cells pre-incubated with -fluoromethylhistidine are unresponsive to compound 48/80 which therefore activates pre-formed histidine decarboxylase rather than inducing it. Non-mast cells showed no change after treatment with compound 48/80.