The effect of pH and methylation on the interaction of deoxycholate with rat liver alcohol dehydrogenase

Summary The activation of rat liver alcohol dehydrogenase by deoxycholate depends on the anionic form of the steroid. Methylation of the enzyme protein leads to an increase of both turnover number and K_m for ethanol and to a change in the effect of deoxycholate, which behaves as an inhibitor. It is suggested that the steroid and methylation effects depend on the same basic mechanism, in which one or more Lys groups are involved.Acknowledgment. We thank Professor A. Guerritore for his help and advice. This work was supported by a grant from the Italian Consiglio Nazionale delle Ricerche.     

Inhibition of human chlorionic gonadotrophin-induced ovarian and uterine growth in the mouse by synthetic arginine vasotocin-1.

21-day-old Swiss-Webster female mice were injected with 1 IU HCG at 09.00 h. Injection of freshly prepared arginine vasotocin (2 mug/0.1 ml/injection) every 12 h inhibited the HCG-induced hypertrophy of the ovaries at 36, 48, 60 and 72 hr after HCG-treatment while the uterine weight was depressed at 60 and 72 h.     

The effect of heat on rat pineal hydroxyindole-O-methyl transferase activity

Summary Exposure of adult male rats to continuously elevated temperature of 32–34°C caused a significant decrease of HIOMT activity involved in the specific metabolic process of production of melatonin, considered an active pineal hormone. The effect was already evident after 24 h exposure and increased further during the next 48 h. The results obtained substantiate previous data that the pineal gland may be involved in the system regulating adaptation to extreme temperature changes.Acknowledgment. The authors are indebted to MissUte Schmidt for her excellent technical assistance.     

Sectioning of polyacrylamide slab gels with a modified small animal stereotaxic instrument

Summary A simple and inexpensive modification of the Kopf model 900 small animal stereotaxic instrument allows it to be used temporarily as a precision polyacrylamide slab gel slicer.Supported by the Alfred P. Sloan Foundation.     

Fluid fluxes in the ferret trachea

Summary A net reabsorption of fluid was observed in isolated ferret trachea under control conditions. Cholinergic stimulation resulted in net secretion of fluid while atropine blocked this response without any effect on the basal process of fluid reabsorption.Supported by research grants from the Cystic Fibrosis Foundation and the University of Florida (GML) and by a Pediatric Pulmonary Center award (A 2018) from the Division of Maternal and Child Health of the Department of Health and Human Services and Whitehall Foundation grant (No. 78-156 ck-1).     

Prostaglandin-induced choleresis in the rat.

It could be demonstrated that intraportal infusion of prostaglandin A1 (1 mug/min/100 g body wt.) in Wistar rats significantly increases bile flow. An analysis of the relationship between bile salt excretion and bile flow revealed that this choleresis is due to an increase in the bile salt independent fraction of bile.     

Effect of des-Tyr1-gamma-endorphin on serotonin metabolism in rat brain regions

Intracerebroventricular (i.c.v.) administration of des-Tyr1-gamma-endorphin (0.1 and 1.0 microgram) caused a decrease of the serotonin (5-HT) concentration of the hippocampus. The concentration of 5-HIAA and the pargyline-induced alterations in 5-HT and 5-HIAA were not affected. No effects were noticed in other brain regions.