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Biomedical subjects

L Sirakov

Publications and source records attributed to L Sirakov.

36 records · Page 2Linked to original sources
PubMed1987

Discrepancy between aldosterone production and renin-angiotensin system activity in Brattleboro rats.

It was demonstrated before that in addition to their typical changes in water-sodium-potassium balance Brattleboro rats, homozygous for hypothalamic diabetes insipidus (DI), revealed a discrepancy between aldosterone level and plasma renin activity (PRA). In the present study PRA was significantly increased (79%), and concomitantly juxtaglomerular (JG) index was increased, reflecting an increased secretory activity of renin-producing JG cells. Plasma concentration of aldosterone was significantly lower (-36%) in DI rats than in their Long Evans (LE) controls. Adrenal blood flow rates were not significantly different in both groups of rats but aldosterone concentrations in the adrenal venous effluents were significantly lower (-66%) in DI rats than in LE rats, suggesting that in vivo production rate of aldosterone was reduced in DI rats. This assumption was confirmed by morphometric data of zona glomerulosa. Our results demonstrated a significant reduction (50%) of angiotensin II receptors in the adrenal glands of DI rats, referring to the number of binding sites and to Kd. This finding threw light on the dissociation between a decreased aldosterone production and stimulated renin-angiotensin system in DI rats.

Adrenal Glands↗
PubMed1981

Content of prostaglandins E and F in the blood plasma and kidneys in arterial hypertension (clinical-experimental study).

A dynamic study is made of the content of PGE and PGF2 alpha in the kidneys of rats with experimental coarctation hypertension, as well as the PGF2 alpha-metabolite in the blood plasma of the same experimental model in rats and in patients with arterial hypertension. The level of the PGF2 alpha-metabolite tends to decrease both in the animals with experimental hypertension and in hypertonic patients. In rats with 30-day hypertension low values are established in 55 per cent, while in 45 per cent there are high values of the PGE level in the kidney homogenate compared with the control group. The concentration of PGF2 alpha in the left ("endocrine") kidney (whose artery originates distally from the place of aortic coarctation) is higher than the concentration of the same PG in the right kidney. Our findings give grounds for the following assumptions: 1. The PGF2 alpha-metabolite as hormone and partly PGE in the kidneys seem to be involved in the pathogenesis of arterial hypertension as compensatory factors. 2. PGF2 alpha in the kidneys probably participates directly as one of the elements of the complex pathogenesis of arterial hypertension.

Adolescent↗
PubMed1979

[Effect of biological agents on glucose-14C utilization by erythrocytes varying in age].

The authors examined young, adult and old erythrocytes from rabbits, aged 15,35 days and 3--4 years. They measured the amount of glucose 14C transfere and metabolized by the erythrocytes during 2-hour incubation at 37 degrees C in a suitable medium. A series of erythrocytes from the three age groups were examined without treatment with chemical agents. Other series of erythrocytes were treated 1 degree minutes before incubation and during its performance with various biological active substances insulin, ACTH, adrenaline, STH, 3AMP, ClCl2. There were differences due to the age in the nontreated erythrocytes. Erythrocytes increased their permeability for grucose and thus its amount was raised in the cells after treatment with insulin. ACTH inhibited this process. Adrenaline, STH, 3AMP and CaCl increased the amount of glucose in the young erythrocytes, obtained from the young animals. The data showed differences in the transfer of glucose 14C and its metabolism in accordance with the chemical and biological properties of the biological agents as well as in accordance with the age of erythrocytes and the animals.

Adrenocorticotropic Hormone↗