The effect of insulin on the electrophoretic mobility of rat hepatocytes

Summary The addition of insulin (10 U) to a suspension of isolated hepatocytes in Krebs-Ringer bicarbonate solution. causes an increase in the negative electrophoretic mobility of the cells from –1.68 m sec^–1 V^–1 cm to 2.26 m sec^–1 V^–1 cm. This observation supports the findings by other workers that the binding of insulin to its receptor leads to a marked change in the membrane.Acknowledgment. We wish to thank the Medical Research Council for the provision of the microelectrophoresis apparatus and initial running costs of the project.     

Reinforcement with naloxone of N-n-propylnorapomorphine (NPA) capability for stimulating male rat copulatory behavior

Summary Naloxone at a dose of 2 mg·kg^–1, which per se did not significantly alter the copulatory pattern of sexually active adult male rats, did significantly reduce the intromission frequency as well as latency to ejaculation when administered before a low and inactive dose of N-n-propylnorapomorphine (0.5 g·kg^–1).     

The levels of metallothionein-like proteins in animal tissues

Summary The level of metallothionein-like proteins was determined in different tissues of 6 animal species. The highest concentrations were found in pig and rat tissues. The organs richest in metallothionein-like proteins included: kidneys (101–305 g/g), intestine (127–257 g/g) and liver (54–496 g/g).Studies performed under the Polish-American agreement 05-009-2 with National Institute for Occupational Safety and Health, PHS, USA.     

Choleretic and cholestatic effects of infused bile salts in the rat

Summary In rats, at low infusion rates taurocholate (TC), taurochenodeoxycholate (TCDC) and taurodeoxycholate (TCD) each produced an increase in bile flow of 20–50%. However, at high infusion rates (5–20 moles min^–1 kg^–1) the cholestatic effects of the bile salts were revealed and the relative toxicity of the bile salts was seen to be TDC>TCDC>TC.     

Evidence against a role of (Na++K+-ATPase in the alpha-adrenoceptor mediated positive inotropic effect of phenylephrine

Summary Phenylephrine (0.1–100 M) in the presence of 1 M propranolol increased the force of contraction in electrically driven papillary muscles from cats. This presumably alpha-adrenoceptor mediated positive inotropic effect of phenylephrine occurred without any influence on (Na⁺+K⁺-ATPase activity.This work was supported by the Deutsche Forschungsgemeinschaft.     

Asscorbic acid portects against male infertility in a teleost fish

An animal unable to synthesize ascorbic acid uniquely minicks human and non-human primates. Therefore, in this study we used the rainbow trout, a teleost fish, as the model animal to study the importance of dietary ascorbic acid on the fertilizing ability of sperm. A high concentration of ascorbic acid in semen plays a key role in maintaining the genetic integrity of sperm cells, by preventing oxidative damage to sperm DNA. This study will show that the concentration of asorbic acid in seminal plasma refelcts the dietary fed either an ascorbate-free diet (from 4.74±0.9 to 0.16±0.08 g ml^–1) or an ascorbate-rich diet (from 37.9±4.7 to 17.7± 3.2 g ml^–1) during the sperimnation season. The relationship between ascrobate status and fertility was studied in six groups of fish fed graded levels of ascorbic acid, which sperimated over a 150-day-period. Sperm from individual males was used to fertilize several batches of eggs. When the seminal plasma ascorbate concentration decreased to 7.3 g ml^–1 a significant decrease of fertilization rate and the hatching rate of embryos resulted. This is the first evidence that dietary ascorbate level directly affected sperm quality and influenced male fertility in a scruvy-prone vertebrate.     

Persistence of added retinoids in organ culture media during induction of mucous metaplasia and glandular morphogenesis in hamster cheek pouches

Summary The retinoid concentration (determined colorimetrically) did not change significantly in retinyl acetatesupplemented (6 g/ml) Eagle's Minimal Essential Medium containing 10% fetal calf serum when stored at –20 or 4°C over 7 days. After the medium was incubated at 37°C for 48 h, 37–49% of the retinoid remained, whether or not tissue (neonatal Syrian hamster cheek pouch) was present, and irrespective of explant age. The normal retinoid level in the tissue was approximately 0.25 g per gram. Therefore, neonatal hamster cheek pouches, incubated in medium with the addition of 6 g of retinyl acetate per ml of medium and undergoing mucous metaplasia and some mucous gland morphogenesis, were continually being exposed to retinoid levels which, though gradually decreasing, remained well above their normal physiological level.     

Kinetics and inotropic action of probenecid in guinea-pig heart in vitro

Summary Probenecid (100–750 g·ml^–1) was found to inhibit cardiac contraction force in untreated and digoxin-treated (100 g·ml^–1) isolated right guinea-pig atrium in vitro by a reversible process, without influencing beating frequency. At low concentrations (1.5–60 g·ml^–1),¹⁴C-probenecid was accumulated into right atrium by an oxygen-dependent process. Correlation between uptake and negative inotropic action of probenecid could not be found.     

Effects of DL-propranolol on exercise heart rate and maximal rates of oxygen consumption inScaphiopus intermontanus

Summary Lymphatic injection of propranolol (0.2–10 g) into toads decreased exercise heart rate in a dose-dependent manner. There was a significant linear corrleation between exercise heart rate and maximal oxygen consumption rates . These data are consistent with the hypothesis that blood oxygen transport is the limiting process for max in anuran amphibians.This work was supported by a grant from the National Science Foundation (PCM-8021808). I am grateful to Dr P.C. Withers for logistical support and Dr S. Yokota for the initial idea.     

Hyposmotic shock-induced discharge in acontia ofCalliactis parasitica is blocked by gadolinium

On acontia ofCalliactis parasitica it was observed that mechanical stimuli applied by a gelatin probe, a method effective in tentacles of Anthozoa, do not induce the discharge of nematocytes. Hyposmotic shock, performed by treatment with NaCl solution 35% hyposmotic with respect to sea water, induces, in the presence of Ca²⁺, the discharge that spreads along the acontial filament, as previously observed following treatment with SCN^–. The hyposmotic shock-induced discharge is blocked by Gd³⁺ at a concentration of 1 M. 10 M Gd³⁺ prevents also the SCN^–-induced discharge. These results suggest the presence of stretch activated cation channels either in nematocytes and/or in supporting cells as well as a possible effect of SCN^– on this class of ion channels.     

Inhibition of hepatic Na+, K+-adenosinetriphosphatase in taurolithocholate-induced cholestasis in the rat

Summary Na⁺, K⁺-adenosinetriphosphatase (Na⁺, K⁺-ATPase) activity was decreased in liver plasma membranes from rats in which cholestasis had been induced by i.v. administration of sodium taurolithocholate (5 moles/100 g b. wt). Incubation of liver plasma membranes with taurolithocholate (10–1300 M) caused significant and dose dependent reductions of Na⁺, K⁺-ATPase activity at taurolithocholate concentrations above 100 M. These findings lend support to the hypothesis that cholestasis induced by monohydroxy bile acids is at least partially the result of an inhibition of hepatic Na⁺, K⁺-ATPase activity.This work was supported by the Swiss National Science Foundation.The authors thank Mr H. Sägesser and Miss B. Schütz for technical assistance.     

Complex formation betweenγ-immunoglobulin and calmodulin in calcium-free conditions

We show that -immunoglobulin (IgG) binds calmodulin (CaM) in a Ca²⁺-independent manner, with Kd value of (1.7±0.5)×10^–7M. A single IgG molecule maximally bound 10 CaM molecules. The binding is to the heavy chain or Fab portion, but not the Fc portion, of the IgG molecules. Ca²⁺ greatly diminished the interaction between IgG and CaM, with IC₅₀=8–9M. These data give a novel insight into protein-protein interactions.     

ATP-dependent Ca++-Extrusion from human red cells

Zusammenfassung In einer Lösung mit 1,39M/ml Ca⁺⁺ waren rekonstituierte menschliche Erythrozyten im Stande, ihren ursprünglichen Ca-Gehalt von 2,39M/ml Zellen in 60 min bei 37 °C auf 0,46M/ml Zellen zu senken, sofern sie Mg-ATPat enthielten. Dieser aktive Transport war durch g-Strophanthin nicht hemmbar, konnte aber mit 5 · 10^–4 M Salyrgan unterdrückt werden.     

Dopamine and cerebral cortical blood flow in the rat

Summary Dopamine topically applied to the cerebral cortex (1–20 g/ml) or administered i.v. (0.5–64 g/kg/min) has no effects on cerebral cortical blood flow in the rat.     

Physicochemical studies of indocyanine green (ICG): absorbance/concentration relationship,pH tolerance and assay precision in various solvents

Summary Indocyanine green (ICG) obeyed the Beer-Lambert law within the concentration range 1.25 g/ml–10.0g/ml in distilled water, methanol, dimethylformamide (DMF), 1.2-propanediol and aqueous buffers (pH 9.0), but only up to 7.5 g/ml in human bile and 0.5% human albumin, and only to 5.0 g/ml in human duodenal fluid. ICG was rapidly (<1 h) decomposed to a colorless derivative at pH<5 and >11, but remained relatively stable for 48 h at pH 8–10. ICG is an indicator and a weak acid with a pKa of 3.27. In bile stabilized with 25% methanol, the precision of the method (CV) is 5% and the accuracy is 106–127%.     

Repercussions de l'hyperthyroïdie sur le contenu total en ADN du cervelet de rat âgé de 6 et 35 jours. Effets comparés de la LT3 et de la DLT4

Summary The total cerebellar proteins RNA and DNA contents from DLT4- and LT3-treated rats was studied at 6 and 35 days of age. The effect of injections of 5 g/j of DLT4 is comparable to that of 25 g of LT3 at birth, followed by 0.5 g every 2 days. On the other hand, injection of 0.5 g of LT3 every 2 days does not induce any significant modification of the total DNA contents in the cerebellum.     

Changes in rat erythrocyte membrane induced byΔ 1-tetrahydrocannabinol,scanning electron microscope study

Summary Although some biochemical dose-dependent effects are revealed in erythrocytes exposed to ¹ (THC) already at concentrations well below 10 M, marked morphological changes of the erythrocyte membrane become evident, by scanning electron microscopy, only at THC concentrations beyound 15 M. These observations provide evidence additional to previous chemical and physical studies, in which 15 M is found to be a critical concentration with respect to the effects of TCH on erythrocyte membrane.Acknowledgments. The authors are indebted to Prof. R. Mechoulam from the School of Pharmacy, The Hebrew University, Jerusalem, for providing the THC. The excellent technical assistance of Mrs R. Mordechai and of Miss L. Motola is gratefully acknowledged.     

Cartsian diver studies on respiration of rat bone marrow cells in the presence of erythropoietin and anti-erythropoientin

Résumé L'étude de la respiration des cellules de la moelle des os du rat fut faite avec un plongeur Cartésien. Ces cellules, avec ou sans glucose, repirent à raison de 0,73±0,15 et 0,97±0,17×10^–6 l O₂/cellule/h. Comparée aux mesures de contrôle, la respiration des cellules médullaires de rats pléthoriques est plus fabile en présence de ESF (0,45 contre 0,99×10^–6 l, O₂/cellule/h). Cette inhibition fut supprimée par la présence d'anti-ESF (0,98 contre 0,99×10^–6 l O₂/cellule/h).

---

---

This research was supported by funds from a Damon Runyon Cancer Research Training Grant and the US Public Helath Seervice. The senior author was a Damon Runyon Post-Doctoral Traince.     

A sensitive protein assay method using micro-titer plates

Summary A commercially available protein-assay, based on the reaction between bicinchoninic acid (4,4-dicarboxy-2,2-biquinoline) and copper was adapted for use in microtiter plates. The assay is sensitive between 10 m/ml and several mg/ml, and it uses only 10 l of sample material. The results obtained with the method were in accordance with other protein determination methods. The assay was shown to be reproducible, reliable and insensitive to non-ionic detergents.Acknowledgments. The authors are grateful to Miss Barbara Moser who skillfully performed a number of these experiments. This research was supported by the Swiss National Science Foundation, Grant No 3.300–0.82, to U.B.     

High and low affinity transport ofL-arginine in rat brain synaptosomes

The uptake ofL-arginine into purified rat brain synaptosomes was investigated with respect to time and various concentrations ofL-[³H] arginine. Specific uptake was found to be linear with time for up to 5 min of incubation at 37°C. Electrolytes, including sodium chloride, potassium chloride, magnesium chloride and calcium chloride, inhibited uptake of 3 ML-arginine, and the inhibitory effect increased with increased electrolyte concentration under constant osmolarity. It was found thatL-arginine was transported into synaptosomes by two uptake components — a high affinity component (3.5 M) and a low affinity component (100 M). These two components were similar to the Ly⁺ system because of their extreme sensitivity to inhibition byL-lysine andL-ornithine but were distinguishable from each other by kinetic analysis of the uptake data and by their relative sensitivity to inhibition by several amino acids.