Nitric oxide-related pancreatic endocrine responses to hyperglycaemia in the conscious calf

Mean plasma insulin concentration was reduced and mean plasma glucose concentration increased following the administration of N-nitro-L-arginine methyl ester (L-NAME; 100 mol kg^–1 i.a.) in conscious calves given continuous infusions of exogenous glucose (30–60 mol min^–1 kg^–1 i.v.). It is concluded that the rise in plasma insulin concentration which occurs in these animals in response to glucose is mediated, at least in part, by a nitric oxide-related factor (NOx).     

Potentiating action of hexoprenaline on14C-aminopyrine uptake by isolated rat parietal cells

Summary Hexoprenaline potentiated the¹⁴C-aminopyrine uptake (a reliable index of H⁺ generation) of isolated rat gastric cells stimulated by 10^–6–10^–4 mol/l carbachol, and inhibited that in response to 10^–4 mol/l histamine without and in the presence of propranolol. It is concluded that hexoprenaline acts as a partial agonist on parietal cell H₂-receptors and that -adrenoceptor activation may functionally modualte gastric acid secretion.Acknowledgments. S. Maliski, Institute of Rheumatology, Warszawa, held a fellowship of the Alexander v. Humboldt-Foundation. The study was supported by the Deutsche Forschungsgemeinschaft. The skilful technical assistance of Mrs R. Maier and Mr R. Beer is gratefully acknowledged.     

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 cerebral lateral,ventricular infusions of phloridzin on feeding and body weight in Gallus domesticus (L.)

Summary Contrary to earlier findings in rats, cerebral lateral ventricular infusions of 1×10^–3 M or 2×10^–3 M solutions of phloridzin at a rate of 2.5 l/min for 90 min had no significant stimulating effects on food intake and weight gain in hens and cocks. These different responses to intraventricular phloridzin might reflect a difference of sensitivity to the inhibitory action of phloridzin on glucose transport in cerebral cells or certain peculiarities of mechanisms controlling food intake in chickens.     

Influence of environmental conditions on the amount of N2O released from activated sludge in a domestic waste water treatment plant

Waste water purification is characterized by intensive mineralization and nitrification processes. Because of the high O₂ demand, temporarily anaerobic conditions may be produced, and denitrification by nitrifying organisms as well as heterotropic denitrification may contribute to N₂O release. In situ measurements (1993–1994) suggest that N₂O is released from activated sludge in a domestic waste water treatment plant at an average rate of 1040 g m^–2h^–1 with a range between zero and 6198 g m^–2h^–1. The production of N₂O seems to be related to the concentration of NO ₂ ^– and NO ₃ ^– as well as to the pH. In the waste water about 75–200 g N₂O l^–1 is dissolved. This N₂O is released after discharge into the receiving waters. The N₂O is produced essentially by nitrification rather than by heterotropic denitrification. On a long-term scale the increasing use of mechanical-biological waste water purification plants world-wide may add increasingly to the anthropogenic production of N₂O, although the present amount of N₂O produced is negligible compared to its global terrestrial production.     

Antagonism by haloperidol of the suppression of exploratory locomotor activity induced by the local application of(−)3-(3-hydroxyphenyl)-N-n-propylpiperidine into the nucleus accumbens of the rat

Summary The injection of (–)3-PPP into the nucleus accumbens, 10 g/side, produced a suppression of exploratory locomotor activity without affecting treadmill locomotion. Furthermore, the suppression of exploratory locomotor activity produced by (–)3-PPP was antagonized by the administration of haloperidol, 25–50 g/kg i.p.Acknowledgments. The figures were prepared by M. Kröning at the Department of Psychology, University of Göteborg. This work was supported by Torsten and Ragnar Söderberg's Foundation, Magn. Bergvall Foundation and Åke Wiberg Foundation.     

Experimental data on the energetic flux during glycolytic oscillations in yeast extracts

Calorimetric experiments were performed on yeast extracts in which glycolytic oscillations were occurring. High metabolic fluxes coincided with low amplitudes and with high frequencies in a temperature range from 283 to 303 K, yielding an activation energy ofE _a=76.8 kJ mol^–1 and a mean Q₁₀ value of 2.5±0.4. The calorimetrically determined reaction enthalpy _fH^0, of the glycolytic catabolism of glucose revealed two distinct groups of extract preparations, with no intermediate values. The values were –107.5±28.7 kJ mol^–1 and –30.8±5.7 kJmol^–1, respectively, while –100.0 kJ mol^–1 was predicted from theoretical calculations. Kreuzberg and Betz⁶ predicted rate limiting effects of GAPDH in oscillating extracts. However, when possible effects of GAPDH on frequency, number of oscillations or total heat production were examined, no influence of increasing or reducing the initial GAPDH concentration could be found. The results are discussed with reference to existing models of glycolytic oscillations.     

Zur Wirkung von Oxytocin auf einen autorhythmischen glatten Gefässmuskel

Summary The influence of oxytocine on the spontaneously contractile portal vein of the rat has been investigated. This octapeptide decreases the active tension and abolished it completely at a concentration of 5×10^–7g/ml. The effect is not caused by an adrenergic mechanism but by a direct action on the smooth muscle cell.     

Effect of pulsing electromagnetic fields on DNA synthesis in mammalian cells in culture

Summary DNA synthesis in Chinese hamster V79 cells was significantly enhanced when they were exposed to weak, pulsing electromagnetic fields generated by specific combinations of the pulse width (25s), frequency (10, 100 Hz) and magnetic intensity (2×10^–5 8×10^–5T). Conversely the DNA synthesis of cells in the fields at 4×10^–4 T was repressed to 80% of that in controls not exposed to the fields.This work was supported by Kaken Pharmaceutical Co., Ltd, Tokyo, Japan, and in part by a Grant-in-Aid from the Ministry of Education, Science and Culture of Japan and from the Foundation for Life Science Promotion Tokyo, Japan to I.K.     

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.     

Insulin acts on the hypothalamic glucose-facilitated neurons to induce hyperglycemia and hyperinsulinemia in the rat

Microinjection of insulin (0.04–0.12 IU/l) into the anterior hypothalamus or the lateral hypothalamus, but not the vertromedial hypothalamus of the rat brain, caused a dose-dependent rise in blood glucose and in serum insulin. The majority (71.5%) of the glucose-facilitated neurons recorded in the lateral hypothalamic area were excited by intracerebral injection of insulin. The data indicate that insulni acts on the hypothalamic glucose-facilitated neurons to induce hyperglycemia and hyperinsulinemia. It is unknown whether insulin normally reaches the hypothalamic area, or how it might do so.This work was supported by grants from the National Science Council (Taipei, Taiwan, Republic of China).     

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.     

Über «therapeutische» und «toxische» Digitoxigeninwirkungen auf elektrophysiologische Messgrössen des Meerschweinchenvorhofs

Summary Therapeutic concentrations of digitoxigenin (10^–7–3× 10^–7 g/ml), producing positive inotropic effects, did not alter resting and action potentials of electrically driven guinea-pig auricles. However, toxic concentrations of digitoxigenin (5 × 10^–7–10^–8 g/ml), producing arrhythmias and contracture of the myocardium, had a marked influence upon resting and action potentials and conduction velocity.     

Influence of cyclic nucleotides on protein synthesis in vascular smooth muscle

Summary The incorporation of leucice-¹⁴C into protein in bovine mesenteric arteries was augmented by cyclic GMP (10^–3 M) and decreased by cyclic AMP (10^–3 M). There was no effect of 5 AMP (10^–3 M). The phosphodiesterase inhibiting drugs theophylline (10^–3 M) and papaverine (5×10^–5 g/ml) both decreased the leucine-¹⁴C incorporation.We are indebted to Mrs.Lena Burlin for hear assistance. Finacial support has been provided by the Swedish State Medical Research Council (No. 04X-101X-4498).     

Cl−/HCO 3 − exchanger is operative in isolated enterocytes from rat jejunum

Enterocytes isolated from rat jejunum were tested for the existence of a Cl^–/HCO ₃ ^– exchange, previously evidenced in basolateral membrane vesicles but not in brush border. Cells were found to retain functional integrity and transport capabilities long enough to allow Cl^– fluxes to be measured. Both efflux and uptake experiments indicate that a Cl^–/HCO ₃ ^– antiport, inhibited by 4,4-diisothiocyanostilbene-2-2-disulfonic acid (DIDS), is functional under resting conditions.     

Green tea epigallocatechin-3-gallate is an inhibitor of mammalian histidine decarboxylase

(–)-Epigallocatechin-3-gallate, an antiproliferative and antiangiogenic component of green tea, has been reported to inhibit dopa decarboxylase. In this report, we show that this compound also inhibits histidine decarboxylase, the enzymic activity responsible for histamine biosynthesis. This inhibition was proved by a double approach, activity measurements and UV-Vis spectra of enzyme-bound pyridoxal-5-phosphate. At 0.1mM (–)-epigallocatechin-3-gallate, histidine decarboxylase activity was inhibited by more than 60% and the typical spectrum of the internal aldimine form shifted to a stable major maximum at 345nm, suggesting that the compound causes a stable change in the structure of the holoenzyme. Since histamine release is one of the primary events in many inflammatory responses, a new potential application of (–)-epigallocatechin-3-gallate in prevention or treatment of inflammatory processes is suggested by these data.Received 8 April 2003; received after revision 20 May 2003; accepted 3 June 2003     

Lack of pressor effect of dopamine in the pentobarbital-anesthetized rat

Summary The blood pressure and heart rate responses to intravenous dopamine infusion at 2.5, 5.0 and 10.0 g·min^–1·100 g^–1 were studied in conscious and pentobarbital-anesthetized Sprague — Dawley rats. In the conscious rats, dopamine caused a significant dose-related increase in the mean arterial blood pressure which was abolished in the anesthetized rats. The heart rate increased significantly only at the highest dose infused. The responses to equipressor doses of noradrenaline (40 ng·min^–1·100 g^–1) and phenylephrine (1.0 g·min^–1·100 g^–1) were also suppressed in the anesthetized rats. The results suggest that pentobarbital anesthesia depresses the blood pressure response to dopamine infusion in the rat through a depression of activation of alpha-adrenoceptors.16 June 1986     

Studies on hydrogen,halides and thiocyanate ions in dioxane-water mixtures at various temperatures

Summary The free enrgies of transfer (G _t ⁰ ) of H⁺, Cl^–, Br^–, I^– and SCN^– ions from water to 10, 20, 30 and 40% dioxanewater mixtures have been studied from potentiometric measurements. For anions the G _t ⁰ values are in the order Cl^–>Br^–>SCN^–>I^–.     

Depletion of hypothalamic norepinephrine reduces the fever induced by polyriboinosinic acid: polyribocytidylic acid (Poly I:Poly C) in rats

Summary Administration of either Poly I:Poly C (0.05–0.50 g) or norepinephrine (2–8 g) into the anterior hypothalamic area produced a dose-related fever in rats. The fever induced by Poly I:Poly C was attenuated after selective depletion of norepinephrine in the hypothalamus. However, selective depletion of hypothalamic norepinephrine did not affect the fever induced by intrahypothalamic norepinephrine. The data indicate that Poly I:Poly C may act to induce fever through the endogenous release of norepinephrine from the rat's hypothalamus.This work was supported by grants from the National Science Council (Taipei, Republic of China).     

Activité antifibrillante chez l'animal d'un nouveau dérivé de la phényl-éthylamine

Summary A new synthetic phenyl-ethyl-amine derivative, the 2-[N- (3, 4-methylen-dioxyphenylethyl)-methylaminomethyl]-tetrahydrofuran, No. 11 081, exhibits a strong protective effect against cardiac fibrillation and arrhythmias produced by various experimental methods: against fibrillation due to aconitine 3 × 10^–8 on the isolated cat's heart, it is active in a concentration of 10^–6–2 × 10^–6. Against cardiac arrhythmias produced in the cat by adrenaline + CHCl₃ or cyclopropane, it shows a protective effect by 5–10 mg/kg i.v. and even perorally by 50 mg/kg. In these tests, the antifibrillatory activity of the new compound seems to be roughly the same as that of -fagarine, and higher than that of procaine.

---

---

9^e communication sur les dérivés des alcoylène-imines; 8^e communication, cf. Exper.10, 261 (1954).