Ammonium Salts Promote Functional Adaptation of Rat Erythrocytes on the Model of Forced Swimming

Bulletin of Experimental Biology and Medicine - Ammonium, an end-product of catabolism, in low doses can promote adaptation of metabolic pathways in erythrocytes under conditions of extreme...     

Efficacy of purine nucleotides on purinergic P2 platelet receptors by small angle light scattering

The effect of purines on the activation and aggregation of thrombocytes in rats and rabbits was studied by the method of small-angle light scattering. The EC50 values of ADP, inducing the activation and aggregation of thrombocytes, reflect the sequence of the agonist action on various receptors: P2X1, 20-40 nM; P2Y1, 90-110 nM; P2YADP, 120-240 nM. It was demonstrated that ADP behaves as partial agonist not only with respect to P2X1 receptors, but with respect to P2Y1 receptors as well. Thrombocytes activated by 20 nM ADP or 100-nM ATP pass into a refracter state in the absence of further stimulation. The reaction halftime is tau 1/2 = 6.0 +/- 0.2 min for the cells activated with ADP and tau 1/2 = 16.5 +/- 0.2 min for ADP.     

Mechanisms by which dolphins identify target movement characteristics and their technical use in hydrolocation and radiolocation

The ability of the localizing system of the dolphin Tursiops truncatus to discriminate the dynamic characteristics of an object being located (a radially moving target) was studied. Measurements were made of the thresholds of the animals’ sensitivity to the target speed (2.6 cm/sec) and acceleration (0.6 cm/sec²). For location of a target moving at constant speed, dolphins were found to use probe signals consisting of two impulses, while accelerating targets were located using probe signals consisting of three impulses. These characteristics were used to propose new and highly effective technical methods for hydrolocation and radiolocation. __________ Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 91, No. 8, pp. 872–884, August, 2005.     

Cooperative Type of Platelet Hypersensitivity to ADP

We found that gestosis is associated with platelet hypersensitivity to ADP. Cell P2X1 receptors exhibited a positive cooperative response to ADP (EC₅₀=10.88±3.70 nM, Hill constant n=2.59±0.50 rel. units). Cooperative binding of ADP to platelet P2X1 receptors was also observed during incubation of cells from pregnant women with isosorbide dinitrate. __________ Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 140, No. 9, pp. 261–264, September, 2005     

Impact of ammonium chloride in a toxic dose on the bioelectrical activity of rat brain

Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 116, N ^o 7, pp. 19–21, July, 1993     

State of the sympathetico-adrenal system in patients with hypothalamic pubertal syndrome

The role of the sympathetico-adrenal system in the pathogenesis of arterial hypertension in pubertal hypothalamic syndrome was studied in 29 males with pubertal hypothalamic syndrome and 13 healthy subjects, aged 15–23 years. The activity of the sympathetico-adrenal system was assessed in terms of the plasma dopamine, noradrenaline, and adrenaline concentrations as determined by HPLC using a high-sensitivity detector. Patients with stable arterial hypertension had significantly reduced levels of adrenaline, probably because of loss of phenylethanol methyltransferase activity, which may demonstrate that the sympathetico-adrenal system is not involved in the genesis and maintenance of arterial hypertension in pubertal hypothalamic syndrome. Patients with a body mass index of more than 35.0 kg/m² had significant reductions in noradrenaline levels, evidently because of loss of tyrosine hydroxylase, whose activity is regulated by corticotrophin. Catecholamine levels were independent of the duration of illness, the duration of hypertension, or the stage of obesity. Endocrinological Scientific Center (Director, Academician I. I. Dedov). Russian Academy of Medical Sciences, Moscow. Department of Endocrinology, Samara Medical University. Translated from Problemy éndokrinologii, Vol. 43, No. 4, pp. 18–20, July–August, 1997.     

Role of atrial natriuretic peptide in the development of arterial hypertension in patients with pubertal hypothalamic syndrome

The role of a depressor factor, atrial natriuretic peptide, in the development of arterial hypertension in adolescents with pubertal hypothalamic syndrome was studied in 52 patients and 13 healthy males aged 13–24 years. The duration of disease was 2–11 years. Radioimmunological methods were used to measure plasma atrial natriuretic peptide, plasma renin activity, and serum aldosterone. Patients with borderline arterial hypertension were found to have a significant reduction in their atrial natriuretic peptide levels, and this correlated directly with the renin-aldosterone system, demonstrating insufficiency of the depressor system in patients with pubertal hypothalamic syndrome and the involvement of atrial natriuretic peptide in the development of arterial hypertension, along with disturbances in the functional relationship between atrial natriuretic peptide and the renin-aldosterone system. This article was presented at the III All-Russian Congress of Endocrinologists. Samara Medical University. Translated from Problemy éndokrinologii, Vol. 43, No. 4, pp. 21–22, July–August, 1997.