Archives internationales de physiologie et de biochimie最新文献

Central antimuscarinic actions of dopamine receptor agonists: N,N-dipropylaminotetrain (TL-68) and 2-di-n-propylamino-4,7-dimethoxyindane (RDS-127), were evaluated against oxotremorine-induced tremors in mice. Both TL-68 and RDS-127 inhibited the tremor intensity but were less potent than atropine.

Mean magnesium concentrations in intermoult Oniscus asellus, caged at 20 degrees C for 10 days, ranged from 1,059.15 +/- 51.9 ppm on diets containing 10 ppm nickel, to 6,827.6 +/- 314.1 ppm on a mixture of 500 ppm magnesium + 10 ppm nickel. Mean nickel concentrations ranged from 89.4 +/- 4.3 ppm on diets containing 500 ppm magnesium, to 314.0 +/- 14.8 ppm on a mixture of 500 ppm magnesium + 10 ppm nickel. At 30 degrees C, magnesium tissue concentrations ranged from 4,149.8 +/- 153.5 ppm on diets with 10 ppm nickel to 12,602.6 +/- 529.3 ppm on 500 ppm magnesium. Nickel concentrations at 30 degrees C varied from 156.8 +/- 6.7 in isopods in the control to 490.5 +/- 23.5 ppm on those on 500 ppm magnesium + 10 ppm nickel. Magnesium in intermoult isopods was mainly stored in other tissues, including the exoskeleton, and nickel in the hepatopancreas. Differences in both magnesium and nickel concentrations between males and females were not significant. Magnesium and nickel concentrations in postmoult isopods, on the average, amounted to 367.6 +/- 16.5 ppm and 18.7 +/- 0.7 ppm, respectively, at 20 degrees C, and 369.9 +/- 16.3 ppm and 30.9 +/- 1.3 ppm, respectively, at 30 degrees C. Differences between males and females, and between various treatments were not significant at P greater than 0.01. It is suggested that both hepatopancreas and other tissues, including the exoskeleton, are used as sinks to get rid of excessive tissue magnesium and nickel during the moult-cycle.

In rat duodenum, in vitro, in the presence of atropine and guanethidine, ATP administration caused a tetrodotoxin-insensitive relaxation followed by a rebound contraction. A similar response was obtained also after electrical field stimulation (EFS) of non-adrenergic, non-cholinergic (NANC) nerves. alpha, beta-methylene-TP and theophylline antagonized the response to ATP, but they failed to affect the noradrenaline- and EFS-induced relaxation. These results suggest that P1 and P2 receptors are present in rat duodenum, but their activation is not responsible for the inhibitor effects due to the NANC nerves.

The functional status of the cutaneous division of the orthosympathetic nervous system was indirectly and non-invasively assessed by monitoring the skin electrical relative resistance variations (SERV). The advantages of our recording system of second generation were (1) simultaneous recording on two or four channels of the evoked electrodermal response to psychic or to sensorial stimulus; (2) self-balancing system which allows the recording of the relative variation of the electric parameter, i.e. its variation with time; (3) precise determination of the amplitude (omega/s, mu F/s) of the evoked response; (4) reference of the latency time (LT) of the evoked response to the length of the anatomical pathway of the signal giving the autonomic conduction velocity (ACV). Decrease in diabetic autonomic neuropathy of both spontaneous and evoked electrodermal activities suggested their relationship with cutaneous sympathetic activity.

Isolated rat duodenum shows spontaneous mechanical and electrical activities. Mechanical activity consists in changes both in endoluminal pressure and in isometric tension. Electrical activity is characterized by slow waves with superimposed bursts. This spontaneous activity is tetrodotoxin (TTX) resistant and therefore it is myogenic in origin. Indeed, TTX pretreatment, even in the presence of atropine and guanethidine, caused an increase in amplitude and in frequency of the electrical and mechanical activities. This finding indicates the presence of tonically active inhibitory intramural non adrenergic, non cholinergic (NANC) nerves. Duodenal longitudinal strips showed a spontaneous mechanical activity resembling that one recorded from isolated segment. Instead, circular strips are quiescent under resting condition and a contractile activity can be detected only after TTX pretreatment suggesting that: i) the circular smooth muscle layer is tonically inhibited by intramural NANC nerves and, ii) the contractions observed in the rat duodenum are due to the activity of the longitudinal one.

The influence of different diets on cholesterol content of liver and muscle of European eel (Anguilla anguilla) was studied for the first time. In control eel, cholesterol constituted near 7.5% of total lipids in liver and about 1% in muscle. Feeding herring meal-55% diet produced a drastic increase in hepatic cholesterol after a 30 d period. In muscle, cholesterol content also increased after any dietary treatment. Free cholesterol represented about 34% of total cholesterol in liver and about 50% in muscle. In both tissues, these percentages increased after any experimental condition assayed. The n-3/n-6 ratio in the fatty acid composition was manifestly low in herring meal-55% diet, mainly due to the minimal amount of total n-3 fatty acids. This fact may account for the increase in liver cholesterol, bearing in mind the hypocholesterolemic effect of the polyunsaturated n-3 fatty acids.

Glutamine synthetase (GS) from brain of Clarias batrachus is purified to about 42-fold and characterized at optimum pH and temperature with respect to its kinetic parameters. Values for apparent Michaelis constant of the enzyme for L-glutamine, hydroxylamine and ADP are 50, 62.5 and 0.833 mM respectively. The very low apparent Km for ADP may be specially related to the expression of GS action under high energy bond and also be evidenced by the requirement of enzyme for a high ionic strength of the ADP. The study is extended by examining the effect of various amino acids and metabolites on GS activity in order to gain further understanding of the changes in kinetics and regulation. It reveals that whereas uridine monophosphate and glutamate act competitively with respect to L-glutamine, carbamylphosphate and asparagine act non-competitively. GS activity is markedly inhibited by leucine, aspartic acid and AMP but not by lysine. ATP and methionine sulfoximine behaved as potent inhibitors of the enzyme in vitro. It is suggested that the teleostean GS has most of the properties similar to those reported for mammalian and avian glutamine synthetases. However, it is proposed that kinetic regulation of this enzyme may play a significant role in ammonia detoxication and rate of formation of glutamine-derived neurotransmitters in fish brain.

The content of tryptophan in a precooked corn meal and in 4 types of selected corn seeds: Zea mays indurata, identata, opaque/2 and Marano synth., has been determined by three different methods: ion-exchange chromatography, spectrofluorometry and spectrophotometry. This content is very low, less than 0.080% d.w. Alimentation for 4 d with a diet composed of precooked corn meal with a tryptophan content less than 0.025% induced the appearance of aggressive-cidal or aggressive non-cidal behaviour towards the mouse in more than half of Wistar rats bred in a room constantly lighted by a sodium steam light. The appearance of this behaviour is probably connected with a decrease in brain serotonin.

Among Labrid fishes (Wrasses), polychromy is very frequent. Indeed, a few species of Symphodus show individuals with a peculiar colouration. On one hand, electrophoretic analysis of muscular proteins (myosin and parvalbumins) reveals no differences between the normal individuals and the coloured morphs of the three species. On the other hand, these analyses display disparities between fishes of the two subgenus (Crenilabrus and Symphodus). Biochemical characters seem to have evolved in the same way that morphological and behavioural ones: the subspecies based only on differences in colouration are not confirmed but the differences between subgenus are revealed.