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Biomedical subjects

K Nagy

Publications and source records attributed to K Nagy.

At least 163 records · Page 9Linked to original sources
PubMed1982

Apparent delay between light-induced receptor current and receptor potential in the Limulus ventral nerve photoreceptor.

We measured receptor potential (ReP) and receptor current (ReC) under voltage-clamp conditions alternatingly evoked by successive identical 10 ms light flashes in the ventral nerve photoreceptor of Limulus. At high stimulus intensities the apparent latency of the ReP is 4-15 ms shorter than that of the ReC. At lower light intensities the difference is even larger. High amplification reveals that the light response starts with two phases corresponding to two current components. The initial first current component rises linearly, is much smaller than the second one and therefore is not detected with standard amplification. This first component, which is more pronounced at low light stimulus intensities, is caused either by a displacement or by a weak ionic current.

Animals↗
PubMed1982

Effect of dietary protein and lipid on the activity of hepatic mixed-function oxidase system in young and adult rats.

Effects of marginal or normal casein diets with different sunflower oil contents were tested on the hepatic mixed-function oxidase system in young and adult male rats. The weight gain and the activity of aminopyrine demethylase, aniline hydroxylase and the content of cytochrome P-450 was decreased only in young rats fed 10% casein and 10% oil containing diets. Both in young and adult animals, independently of casein consumption, the activity of MFO with the exception of cytochrome P-450 in adult rats fed 20% casein was significantly higher when the level of dietary sunflower oil was shifted from 10 to 30%.

Aging↗
PubMed1981

Single channel Ca2+ currents in Helix pomatia neurons.

Unitary Ca2+ currents of TEA injected Helix neurons were recorded in the "Giga seal" situation (6,7) from microscopic membrane patches exposed to 50 mM [Ca2+]o, O [Na+]o, 20 mM [TEA+]o and 2.5 microM [TTX]o. Constant field assumptions yield a channel permeability of 2.9 +/- 1.0 x 10(-14) cm3s-1 corresponding to slope conductances of 5 to 15 pS between 0 and -30 mV. Frequency of occurrence of the units strongly increased with depolarization. Mean open time of the Ca2+ channels was about 3 ms without obvious dependence on voltage. A similar open time was seen with [Ba2+]o, yielding about double the current strength when compared with [Ca2+]o.

Animals↗
PubMed1981

In vivo selection of two agents differing in hepatoma-inducing activity from strain MC29 avian leukosis virus.

MC29 virus induces acute leukemia (myelocytomatosis) and primary tumors of liver (hepatomas) in turkey poults. By in vivo passages two viruses were selected; designated "liver" and "bone marrow" variants, differing in hepatoma-inducing activity. The "liver" variant induces hepatoma and acute leukemia, the "bone marrow" variant induces acute leukemia. The variants differ in leukemogenic activity. The "bone marrow" variant induces high grade leukocytosis, while the "liver" variant causes lymphocytosis and heteropenia. The variants also induce the appearance of primitive myeloid cells in the blood. The kinetics of accumulation of viral gs protein (p27) and the presence of viruses inducing hepatoma and leukemia were studied in organs of infected turkeys. The differences between the variants showed no relationship with their selective reproduction capacity in liver and/or bone marrow cells. The results obtained suggest that different viral particles are responsible for the induction of leukemia and hepatoma.

Animals↗
PubMed1981

Effect of dietary carbohydrates and ethanol on the activity of microsomal drug-metabolizing enzymes in rat liver.

Effects of fructose, starch, lactose plus starch and ethanol on the drug-metabolizing enzyme system of the liver were analyzed in rats fed fructose, starch or lactose plus starch diets for 21 days. The activity of aminopyrine demethylase and aniline hydroxylase and the level of cytochrome P-450 increased significantly in rats fed lactose plus starch compared to the groups fed fructose or starch diets. The activity of aniline hydroxylase increased as a result of ethanol, independent of the nature of the carbohydrate but in this case the highest activity was also found in the livers of rats previously fed a lactose plus starch diet.

Aminopyrine N-Demethylase↗
PubMed1981

Effect of reduced extracellular sodium concentration on the function of adrenal zona glomerulosa: studies in conscious rats.

The present experiments were designed to study the effect extracellular hyponatraemia on aldosterone secretion. Hyperaldosteronism was induced by peritoneal dialysis with 5% glucose solution in dexamethasone-pretreated rats. In the narrow physiological range of 135-142 mmol/l, as well as in the whole range of the study (122-142 mmol/l), the plasma concentration of sodium showed a close negative correlation with the serum concentration of aldosterone (r = -0.71 and -0.83, respectively). Plasma renin activity increased after peritoneal dialysis; however, no close correlation was observed either between sodium concentration and plasma renin activity or plasma renin activity and serum aldosterone concentration within the dialysed group. The ratio of serum concentration of aldosterone to plasma renin activity showed no considerable change between 132 and 142 mmol/l but rose steeply below 132 mmol sodium/l suggesting that a factor(s) other than angiotensin may also contribute to the induction of hyperaldosteronism.U

Adrenal Glands↗
PubMed1980

Nutritional toxicological studies with Lannate: interactions with caffeine and ethanol.

Effects of the ingestion of Lannate (200 mg/kg diet), caffeine (30 mg% aqueous solution) and ethanol (10% aqueous solution) both separately as well as the ingestion of Lannate with caffeine or ethanol were studied in R/Amsterdam rats. Response to the combined administration of Lannate and caffeine produced evidence of interactions only in female rats. The combined ingestion of Lannate and ethanol resulted in some interactions both in female and male rats, however, sex differences were apparent regarding certain parameters.

Animals↗
PubMed1979

Hepatic metabolism in ethanol-treated young rats.

Dams of a Wistar-derived OETI strain were offered a 15% aqueous ethanol solution as drinking-fluid immediately after delivery until weanling. Their offsprings also received the same drinking-fluid from weanling (Group A). Another group of rats received the 15% aqueous ethanol solution only after weanling (Group B). In response to ethanol treatment the retardation of growth was the most marked in Group A, but the growth of rats in Group B was also decreased significantly as compared to that of controls. Hepatic glycogen content was diminished in all of the ethanol-treated groups. Triglyceride content was increased in the livers of female rats in Group A. By comparing earlier results with the present findings the authors point to the importance of strain and sex in experiments when parameters for hepatic metabolism are studied in response to ethanol.

Animals↗
PubMed1979

Hyperaldosteronism in the sodium-depleted rat: mechanism of aldosterone stimulation by peritoneal dialysis with glucose solution.

Peritoneal dialysis with 5% glucose solution was carried out in dexamethasone-pretreated rats. Dialysis brought about a severe loss of sodium and a slight loss of potassium into the peritoneal fluid. This kind of sodium depletion took place without any decrease in total body-water space, thus it evoked a severe fall in plasma sodium concentration. Plasma renin activity and the serum concentration of aldosterone increased in response to dialysis. Peak values in renin activity were attained within 60 min, whereas aldosterone concentrations exhibited a continuous rise until at least 120 min. Despite the correlation of renin and aldosterone values, neither the administration of an angiotensin I converting enzyme inhibitor (SQ 20,881) nor the reduction of plasma renin activity by indomethacin could reduce hyperaldosteronism evoked by peritoneal dialysis. Therefore, it is assumed that there is no causal relationship between renin and aldosterone in this kind of acute, severe sodium depletion.

Aldosterone↗
PubMed1979

Effect of ethanol on certain metabolic pathways in young R/Amsterdam rats.

R/Amsterdam rats were offered a 15% aqueous ethanol solution as drinking fluid from delivery via the milk (Group A) or from the weanling (Group B). Ethanol treatment resulted in a significant retardation of growth in both Groups A and B compared to controls (Group C); the changes were more marked in Group A. Female rats responded to ethanol with higher increase of microsomal G6P-ase and mixed function oxygenase activities than males subjected to the same treatment. Hepatic triglyceride, glycogen and protein contents remained unaffected by ethanol. There was no difference in the changes of liver metabolism between Groups A and B either receiving ethanol already from birth via the milk or only after weanling.

Animals↗