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Biomedical subjects

J R Rapin

Publications and source records attributed to J R Rapin.

At least 73 records · Page 4Linked to original sources
PubMed1979

[Brain rat histoenzymological changes induced by microsphere injection during ischemia (author's transl)].

The cerebral thrombosis of the rat with 35 micrometer labeled microspheres gives infarcted areas easily seen. After 15 min, in these areas, there is no change in NADH diaphorase-, succinic-dehydrogenase-, mono-amino-oxidase-, glucose-6-phosphate-dehydrogenase-, isocitric dehydrogenase-, lactic-dehydrogenase-, ATPase, alpha galactosidase-, acid phospatase activity. After 2, 4, 6 h all these activities diminish in the neuropil but they are preserved in the neurones for diaphorase, succinic-dehydrogenase and mono-amino-oxidase. The margin of infarcted areas shows a strong staining for acid phosphatase. Before 2 h there is not enzymatic changes neither oedema. This experimental model seems trustly and could be developped.

Animals↗
PubMed1978

[Kinetics of Mn2+ ion metabolism in rat hepatic tissue].

Intravenous injection of MnSO4 with 54Mn (0,33 mg/100 g) into rats showed that Mn2+ ions are transferred into intracellular organites and specially into mitochondria. The mitochondrial clearance curve of 54Mn has been analyzed. It is appeared that three compartments participate in the distribution of Mn2+. The third compartment is the most important.

Animals↗
PubMed1977

Effects of amphetamine on brain biogenic amines in isolated and aggregated rats.

d- and 1-amphetamine were injected (15 mg/kg i.p.) into isolated or aggregated rats. Both d- and 1-forms decreased the noradrenaline levels of brain areas in isolated and in aggregated rats. d-Amphetamine decreased 5-hydroxytryptamine (5-HT) and 5-hydroxyindolacetic acid (5-hiaa) levels in aggregated rats only. 1-Amphetamine induced no change in 5-HT and 5-HIAA levels. The greater sensitivity of aggregated rats to d-amphetamine can be ascribed to a change in 5-HT metabolism rather than to a modification of noradrenaline levels.

Amphetamine↗
PubMed1977

Uptake of noradrenaline in high altitude native's heart.

Uptake of 3H-noradrenaline by the heart was studied with sections of isolated atria obtained from high or lowlanders. In native highlanders, affinity for 3H-noradrenaline by human atria is more significant than in lowlanders. Furthermore, the Michaelis Menten constant is lower in high altitude native's heart.

Adaptation, Physiological↗
PubMed1977

Uptake, turnover and release of norepinephrine in pigmented and albino rat eye.

The uptake, turnover and release of norepinephrine were studied in the rat eye as a function of its pigmentation. The endogenous norepinephrine level was increased in eyes with melanic pigments and the exogenous amine uptake was decreased. In the coloured eye, two sites for norepinephrine uptake and release were present. Desipramine did not inhibit in the same manner the amine in the albino and pigmented eye. No variation was found in the norepinephrine biosynthesis for the two races of rats. The release rate of exogenous amine was higher in the pigmented rat eye.

Albinism↗
PubMed1976

High altitude influence on the level and turn-over time of cardiac norepinephrine in rats.

In rats exposed to an altitude of 2,900 meters the level of endogenous cardiac norepinephrine decreases after the 5th day of exposure. The turner-over time of the amine proceeds in 3 steps which are probably related to periods of stress and adaptation: initial increase, important decrease from the 5th day and return to a normal value from the 12th day.

Adaptation, Physiological↗
PubMed1976

[Kidney uptake of bismuth as an index of its digestive absorption in mice].

The authors studied the absorption of bismuth administered per os as an insoluble salt: basic nitrate and phosphate, labeled with 206Bi. The bismuth amounts in blood and most tissues were too small to be detected. However, kidneys took up a significant bismuth quantity which allowed us to measure the absorption of the metal through digestive wall. Bismuth absorption from phosphate, a very insoluble salt, was much less than that which was obtained from basic nitrate; this latter is an example of partially soluble salt in the stomach.

Atropine↗
PubMed1976

[Effect of normobaric and hypobaric hypoxia on norepinephrine turnover in the rat heart (author's transl)].

1. After administration of 3H norepinephrine (NE), the turnover rates of NE were determined by the decrease in radioactivity. 2. Rats were housed by groups in chambers and either maintained as controls or exposed to a hypoxic environment (PIO2 = 90 torr). The turnover rates of NE were not altered by normobaric hypoxia (fig. 1, table I). 3. Hypobaric hypoxia (barometric pressure was reduced to 500 mm Hg and PIO2 was 105 torr) increased the turnover rates of NE (fig. 2, table II). 4. The role of the sympathetic nervous system during exposure to hypoxia in Rats is discussed with regard to functional adaptation.

Adaptation, Physiological↗
PubMed1976

[Role of central catecholamines in the psychostimulant activity of pyrovalerone].

A comparative study of the effects of alpha methylparatyrosine (alpha MPT) and/or reserpine pretreatments on mice motorhyperactivity and rat stereotyped behaviour induced by pyrovalerone and amphetamine suggests a different mechanism for these two substances. Both behavioral effects were abolished by alpha MPT but not altered by reserpine in the case of amphetamine which presumably acts through a selective release of "newly synthesized" catecholamines from a "functional" pool. In contrast to this, pyrovalerone would increase spontaneous motor activity through a preferential release of norepinephrine from a "storage" pool since motorhyperactivity was not altered by alpha MPT especially during the first phase, whereas it was abolished by reserpine. Stereotyped behaviour induced by pyrovalerone, was still present after pretreatment with alpha MPT or reserpine; these data suggest an action through a release of both "newly synthesized" and "stored" dopamine. On the other hand, a direct action on dopamine receptors might be involved after high doses of pyrovalerone and amphetamine since stereotyped behaviour was found to be present after a combined pretreatment with alpha MPT + reserpine.

Amphetamine↗
PubMed1976

[Pharmacokinetics of DL-norephedrine 14C in the rat].

After i.v. administration of DL-norephedrine 14C to the rat (535 mug/kg), approximately 75% of the radioactivity was eliminated during the first 18 hr in the urine. Beside the unchanged drug (71.5% of the total urinary radioactivity), the main metabolite was alpha-methyloctopamine (18%), a parahydroxylated derivative of which 68% were excreted as glucuronide conjugates. Kinetic studies of DL-norephedrine in different organs showed that the affinity of tissues for the amine did not change with time. Captation was important and rapid in lungs, adrenals, spleen and heart. The brain was marked by a slow increase of drug level during the first 2 hr. However, the terminal semi-exponential kinetic slopes of DL-norephedrine concentration showed that the elimination processes of the drug were the same in each tissue. The affinity of tissues for alpha-methyloctopamine was shown to be much more specific; its uptake was higher in organs which are rich in adrenergic nerve endings (heart, adrenals and spleen). These results confirm the role of this hydroxylated amine as a false neurotransmitter. A whole body autoradiography in the mouse showed an important uptake of DL-norephedrine 14C in salivary glands and periocular structures.

Animals↗