Hemolytic action of potassium salts on dog red blood cells

Recent demonstrations of chloride-associated passive potassium movements in red blood cells of humans, ducks, sheep, and toadfish prompted a reinvestigation of potassium permeability in dog red blood cells. Early observations of Davson (J. Physiol. London 101:265-283, 1942) had shown that replacement of chloride by nitrate and thiocyanate caused a greatly increased rate of potassium flux across the dog red cell membrane. This finding seemed at variance with results in other species in which chloride replacement caused a fall in potassium flux. The present data indicate that passive potassium movements in swollen dog red blood cells are chloride dependent and furosemide sensitive, as shown for the cells of other species. Davson's findings were demonstrated to be due to the inclusion of small quantities of calcium in the medium under circumstances that favored calcium entry into the cells, thus opening the calcium-activated potassium channel described by Gardos (Curr. Top. Membr. Transp. 10:217-277, 1978 and Nature London 279:248-250, 1979). Potassium movements through the latter channel were stimulated when chloride was replaced by more permeant anions, such as nitrate and thiocyanate, which also increased the rate of net potassium movements in valinomycin-treated cells.     

Central antinociceptive action of histamine: Behavioural and electrophysiological studies

The effects of intracerebroventricular (i.c.v.) injection of histamine (HA), an H₁-agonist (2-pyridylethylamine, 2PEA) and an H₁-antagonist (pyrilamine, PYR) on hot-plate latency in rats were examined. HA (40 or 80 g/rat) significantly enhanced the pain threshold whereas 2PEA (80 or 160 g/rat) and PYR (20 g/rat) had no effect. Moreover, PYR did not modify HA antinociception. These results indicate that HA-H₁ receptors are not involved in the inhibition by HA of the hot-plate response. To characterize the neural pathways involved in the antinociceptive action of HA, the effect of HA (40 g/rat, i.c.v.) on the firing of thalamic neurons in arthritic rats evoked by peripheral noxious stimuli was recorded by electrophysiological techniques. HA markedly depressed the neuronal firing evoked by ankle mobilization, suggesting that the thalamus is one important area involved in modulation of pain by HA.     

Chronobiological aspect of the mechanism of lithium salts action in experimental alcoholism

After consumption of a 5% solution of ethanol for two months the diurnal rhythm of histophysiological activity of the rat pineal gland was found to be disorganized. A course of lithium chloride injections in doses corresponding to those used clinically reversed these changes and prevented their development if given during the two months' consumption of ethanol. This effect of lithium correlated with the suppression of preference for ethanol observed under these experimental conditions, or with the prevention of its development. The possible link between this property of lithium salts to reverse chronobiological disturbances of pineal activity and their clinical efficacy in alcoholism and other affective disturbances with a periodic course is discussed.Laboratory of Drug Toxicology, Institute of Pharmacology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medial Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 8, pp. 194–197, August, 1978.     

Central action of new derivatives of tetrahydropirimidinedione-4,6.

The central action and LD50 of 11 new 2,5-substituted derivates of tetrahydropirimidinedione-4,6 with an aryl group at C2 were investigated. The most favorable action was exerted by 2-furfurylamine derivatives with an alkil or benzyl group at C5. These compounds acted in doses of 0.0025--0.01 of their LD50 synergistically with chloral hydrate and strongly with hexobarbital, delayed convulsions induced with pentetrazole and potentiated the central action of DOPA in mice pargyline-inhibited MAO activity. They did not antagonize electrogenic convulsions, amphetamine potentiated motility and the action of reserpine, and had no analgetic action. Their LD50s were 670-- 1660 mg/kg.     

Toxic action of salts of heavy metals on intact and irradiated mammalian cells in culture

I. M. Sechenov Moscow Medical Academy. Institute of Biological Physics, Academy of Sciences of the USSR. (Presented by Academician of the Academy of Medical Sciences of the USSR G. I. Rumyantsev). Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 113, No. 3, pp. 280–283, March, 1992.     

Central action of new imido derivatives of succinic acid.

New imido derivatives of succinic acid were screened pharmacologically with regard to their influence on the central nervous system. No relation was found between the character and position of substituents and depressant action on the CNS. However, it was remarked that potentiation of the central influence of DOPA probably depends on the position of the p-chlorophenyl group.     

Central action of prostaglandins in spawning behaviour of female goldfish.

Removal of the ovipore, oviduct, and posterior portion of the ovary failed to block the induction of female spawning behaviour by intramuscular injections of PGF_2α (100 ng/g). Stereotaxic injections of PGF_2α(10 ng/g) into the preoptic recess of the third ventricle were more effective in inducing female spawning behaviour, than the same dose of PGF_2α given either intramuscularly or intraperitoneally. At 100 ng/g, intraventricular injection of PGF_2α, PGE₂, and PGE₁ induced female spawning behaviour, whereas at 10 ng/g only PGF_2α was effective. These findings indicate that PGs act centrally to induce spawning behaviour in female goldfish providing appropriate external stimuli (male goldfish and aquatic vegetation) are present; spawning behaviour may be triggered by PGs produced in the ovary at ovulation. Possible relationships between PG-induced female sexual behaviour in the goldfish and rat are discussed.     

Combined action of salts of heavy metals and phenol on energy metabolism of isolated rat liver mitochondria

All-Union Research Center for Safety of Biologically Active Substances, Staraya Kupavna, Moscow Region. (Presented by Academician of the Academy of Medical Sciences of the USSR P. V. Sergeev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 113, No. 1, pp. 47–50, January, 1992.