Acta physiologica Academiae Scientiarum Hungaricae最新文献

The effect of prostacyclin (PGI2) and colchicine on fundic gastric mucosa of sexually mature female Wistar rats was investigated histochemically after restraint stress. Under PGI2 treatment the ulcer index decreased significantly; this effect was moderately inhibited by colchicine. The mucus content of epithelial cells was decreased during restraint and was increased by PGI2 treatment. This protective action was also inhibited by colchicine. The nuclear volume of fundic epithelial cells increased significantly in restraint and decreased following colchicine application. These phenomena were not influenced by PGI2. According to our results the cytoprotective effect of PGI2 is not accompanied by nuclear volume changes.

Ni-induced coronary vasoconstriction has been studied in the dog heart in situ in the presence of the selective Ca-antagonist verapamil, and after blocking the alpha-receptors with phenoxybenzamine (PBZ). Verapamil totally abolished the coronary blood flow (CBF) and basal conductance (BC) decreasing effect of low doses of Ni2+ (0.02-0.2 mg/kg-1). The effect of higher doses of Ni2+ (2.0-20.0 mg/kg-1) was reversed by verapamil, i.e. high doses of exogenous NiCl2 increased CBF and BC in the presence of verapamil. The CBF decreasing effect of nickel was not significantly influenced by PBZ pretreatment. The results indicate that trace amounts of exogenous NiCl2 induce coronary vasoconstriction in the dog heart in situ by enhancing Ca2+-influx into vascular smooth muscle cells, which is not mediated by alpha-receptors.

Solutions of KCl (1%, 10% and 31.2%) administered into the pericardial fluid or applied onto the surface of the heart evoked a dome-like change of the ECG in dogs, rats and guinea-pigs and led to myocardial infarction in 3-5 days. Both the acute changes in ECG and the infarction itself could be prevented by the application of pericardial fluid samples and by administration of three synthetic compounds onto the heart surface. The same substances also inhibited the development of ECG changes elicited by general hypoxia due to stopping artificial respiration. The existence of a peculiar myocardial space beginning with outer pores and reaching the myocardial cells through connective tissue pathways is postulated. Earlier studies showed that 125I-labelled albumin applied to the epicardial surface through a filter paper reached the endomyocardium through some intramyocardial pathways beginning with epicardial pores. In the present experiments intrapericardial application of India ink led to obstruction of these pores and thus prevented the infarction elicited by intrapericardial administration of KCl solutions. This space, being distinct from that accessible from the coronary arteries, serves for transfer of various substances into the myocardium, while other compounds (e.g. noradrenaline) are not effective through this pathway. Oxygen reaching this space from the epicardial surface protects the myocardium from the damaging effects of hypoxia and KCl.

The new total herbicide Toxurazine was subjected to general toxicologic and neurotoxicologic examinations. Rats were treated with 1/80, 1/40 and 1/20 of the acute oral LD50 for three months. The animals showed a decrease in body weight and a transitional anaemia. The product had a slight liver damaging effect. Renal function tests and urine analysis were negative. With time, the learning ability of animals tested in maze for 42 days became impaired dose dependently. At the end of the treatment, both at rest and on flashlight stimulation, as well as in complex EEG activity and in each frequency band there was a decrease in electric activity. In electroneuromyographic tests no effect damaging the peripheral nervous system could be detected. The hot plate method showed the reaction time of the animals to be slightly extended. The results suggest that the compound should only be used in uncultivated areas.

The present studies were designed to monitor metabolic perturbations following changes in contractile activity and ion transport in rat and rabbit myometrium by simultaneous measurement of NADH fluorescence, lactate production and isometric force. Stimulation (127 mM K+) and inhibition (Ca2+-deficient solution) of isometric force development induced a decrease/increase of fluorescence intensity corresponding to a more oxidized/reduced state of tissue pyridine nucleotides, respectively. If tension development was abolished by EGTA, fluorescence changes due to altered ion transport could be monitored. Slow progressive stimulation of the sodium pump by Ca2++-deficient solution resulted in an ouabain (10(-3) M) sensitive monophasic NADH oxidation, which was reversed by inhibition of the pump by isotonic K+ solution. If, however, stimulation of the pump was rapid and maximal (addition of 30 mM KCl to Na+-loaded tissues) the fluorescence response was triphasic and ouabain sensitive: it consisted of an initial NAD reduction followed by a transient NADH oxidation and a second slow NAD reduction. These fluorescence changes are interpreted in terms of separate redox changes in the cytoplasm and mitochondria. The ouabain sensitive stimulation or inhibition of Na/K transport was always accompanied by parallel changes in uterine lactate production irrespective of the actual contractile state of the myometrium. The present results show that 1 fluorescence technique can be applied to monitor metabolic perturbations in the uterus evoked by changes in contractility or ion transport; and 2 aerobic glycolysis and Na/K transport are tightly coupled in the myometrium.

Minced rat brain deprived of cerebellum was dissociated by trituration through stainless steel screen and nylon meshes, then by velocity sedimentation technique free-floating perikarya were separated from cell syncytia and cellular debris. The presence of Fc-receptor and C3b-receptor activities, as well as the absence of membrane-bound immunoglobulin and receptor for sheep blood cells were demonstrated on separated perikarya of the rat brain.

The effect of renal function of an augmentation of the excretory renal mass was investigated in 10 dogs without drug treatment and in 10 animals with alpha-receptor blockade. In the untreated group, augmentation of excretory renal mass by transplantation into the neck of one pair of kidneys isolated from another animal caused the following changes in the kidneys in situ: marked elevation in CPAH, slight decrease in Cinulin, slight diminution of urine excretion and a pronounced fall in sodium excretion. The amount of urine and sodium excreted by the four kidneys was identical with that previously excreted by the two kidneys in situ. In animals with alpha-receptor blockade, augmentation of the excretory renal mass had the following consequences in the in situ kidneys, CPAH, and Cinulin remained unchanged while urine and sodium excretion decreased to the same extent as in the untreated control group. The amount of urine and of sodium excreted by the four kidneys was the same as that excreted by the kidneys in situ, prior to transplantation of isolated kidneys, i.e. before the augmentation of excretory renal mass. It seems that the decrease in sodium excretion of the kidneys in situ was not due to the haemodynamic changes evoked by the load on the circulation; it was rather consequence of some quick, presumably humoral, regulation. The diminution of sodium excretion in the kidneys in situ after augmentation of the excretory renal mass has been ascribed to an increased utilization by the four kidneys of the natriuretic factor(s), i.e. to a diminution in the plasma level of the natriuretic hormone.

The Minimal Steric (Topologic) Difference method was applied to map some prostaglandin receptors. Experimental data concerning luteinizing activity of corpora lutea, and pressor respectively depressor activity on sheep blood were considered. The linear correlation coefficients obtained were r = 0.927 (N = 12) for luteinizing activity, r = 0.943 (N = 15) for depressor activity, and r = 0.943 (N = 12) for pressor activity. Similarities and differences between these three receptors are discussed.

It was established that oxidosis evoked by methylene blue during k-strophantoside and acetylcholine contractures in skeletal muscle was accompanied by an increase in the changes of [K+]0 activity, while redosis evoked by ascorbate under the same conditions was accompanied by a decrease in the changes of [K+]0 activity. These changes in [K+]0 activity parallelled the alterations of contractures caused by oxidosis or redosis suggesting that changes in the [K+]0 transient play an important role in these phenomena.