[Changes in the activity of 5'-nucleotidase and protein kinase of the hepatic plasma membrane depending on the dose rate in x-ray irradiation of rats]. / Izmenenie aktivnosti 5'-nukleotidazy i proteinkinazy plazmaticheskoi membrany pecheni v zavisimosti ot moshchnosti dozy pri rentgenovskom obluchenii krys.

In studying the effect of X-irradiation of rats with a dose of 4 Gy at different dose rates (96 and 4.6 cGy/min) the authors have revealed an increase in 5'-nucleotidase activity at a high dose rate (the first 24 h following irradiation) and a decrease in protein-kinase activity at a low dose rate (on days 3 and 7). The preinjection of alpha-tocopherol prevents the changes observed.

[Identification and properties of insulin receptors in neuroblastoma C 1300 N 18 cells in various functional states]. / Identifikatsiia i svoistva insulinovykh retseptorov v kletkakh neiroblastomy C 1300 N 18 pri razlichnykh funktsional'nykh sostoianiiakh.

The presence of insulin receptors in neuroblastoma C 1300 N18 cells was shown by the method of the [125I]insulin binding with cells as well as by the electron-cytochemical methods based on the analysis of the binding of colloid gold-labelled insulin and of agglutinin of wheat embryos with the surface of plasma membrane. It is established that the number and distribution of insulin receptors depend on the functional state of cells. Expression of receptors on the membrane increases after 5'-deoxyuridine-induced differentiation of cells. Due to changes in the lipid composition of cells caused by the incubation with lecithin-cholesterol liposomes (an increase in the content of cholesterol and its esters, as well as of unsaturated fatty acids and appearance of lysolecithin) the quantity of insulin receptors decreases and cell membranes are damaged. The lowering insulin regulation is not observed for insulin receptors of the neuroblastoma C 1300 N18 cells.

[Binding properties of insulin receptors in adipose tissue and hepatic plasma membranes in rats during fasting and in alloxan diabetes]. / Sviazyvaiushchie kharakteristiki insulinovykh retseptorov v zhirovykh i pechenochnykh plazmaticheskikh membranakh krys pri golodanii i alloksanovom diabete.

The affinity and number of receptors were determined using Scatchard's, Meytes' and Rose's graphic analyses in the hepatic and fat plasmatic membranes of rats in various duration of hunger (2 and 7 days) and alloxan diabetes (3 and 7 days after alloxan administration) to test a hypothesis that increased affinity of insulin receptors was the first phase of their activation preceding an increase in the number of insulin binding sites. Irrespective of hunger duration an increase in the number and affinity of receptors was detected in the hepatic membranes and an increase in their affinity in the fat membranes. In diabetes of various duration the number of receptors in the membranes of both tissues increased. With an increase in the period of exposure the degree of expression of receptor changes decreased in the fat but not in the hepatic membranes.

[Additive nature of the stimulating effects of alloxan diabetes and fasting on the specific binding of insulin with its receptors in the plasma membranes of adipose and hepatic cells in the rat]. / Additivnost' stimuliruiushchikh éffektov alloksanovogo diabeta i golodaniia na spetsificheskoe sviazyvanie insulina s ego retseptorami v plazmaticheskikh membranakh zhirovykh i pechenochnykh kletok krysy.

Properties of insulin receptors were studied in rat fatty tissue and in plasmatic membranes of liver cells under conditions of alloxan diabetes (within 3 days) and in fasting (within 2 days) as well as under conditions of simultaneous effect of these factors. In the diabetes amount of receptors in plasmatic membranes of both these tissues, affinity of fatty cell membranes as well as amount of the receptors and their specific affinity in hepatic cell membranes were increased. Specific binding of insulin was distinctly increased under conditions of simultaneous influence of diabetes and fasting due to elevation in content of the receptors in liver cell membranes and in both their content and affinity in fatty cell membranes. The data obtained suggest that alloxan diabetes and fasting caused additive effect on expression of insulin receptors in fatty and hepatic cell plasmatic membranes as well as that the content of receptors on the cell surface was regulated by means of several mechanisms.

[Insulin receptors of adipose tissue in patients newly diagnosed with insulin-dependent diabetes mellitus]. / Insulinovye retseptory zhirovoi tkani u vpervye diagnostirovannykh bol'nykh insulinzavisimym sakharnym diabetom.

Binding of insulin to fatty cell plasmatic membranes in 10 patients with insulin-dependent diabetes mellitus exhibited high variability. The patients were divided into two groups based on the values of insulin binding. In the first group, comprising 3 patients, specific binding of insulin was below the values found in healthy persons; this phenomenon occurred only due to a decrease in content of insulin receptors. In the second group (7 patients) specific binding of insulin exceeded the values of controls; in this case an increase in affinity of the receptors was observed. These results suggest that insulin-dependent diabetes mellitus is characterized by high heterogeneity.

[Absence of the reaction of insulin receptors to receptorotropic activity in the rat liver with innervation lesions]. / Otsutstvie reaktsii insulinovykh retseptorov na retseptorotropnye vozdeistviia v pecheni krys s narushennoi innervatsiei.

Section of the hepatic nervous plexus did not affect insulin receptor parameters in hepatic or adipose tissue plasma membranes. In control rats, the increase of the receptor insulin binding in fasting and its fall under experimental hyperinsulinemia were found both in hepatic and adipose tissue membranes, while in the rats with lesioned hepatic innervation these changes only occurred in adipose tissue membranes. No insulin receptor response to fasting or hyperinsulinemia in the rat liver with lesioned innervation occurred. The vegetative nervous system seems to affect the insulin receptors in the insulin target tissues. The nervous regulation of the receptors in addition to the humoral one, increases the effectiveness of the insulin metabolic control in its target cells.

[Effect of glucocorticoids and adrenaline on insulin receptors in plasma membranes and nuclear envelopes of the rat liver]. / Vliianie gliukokortikoidov i adrenalina na insulinovye retseptory plazmaticheskikh membran i iadernykh obolochek kletok pecheni krys.

To elucidate the course of regulation of insulin receptors in nuclear envelope and its relationship with insulin receptors in the plasma membrane a comparative study of these receptors in both subcellular fractions was conducted under the influence of the involved cell surface receptor factor. It is found that under adrenalectomy the number of nuclear envelope receptors and degree of their affinity did not increase as this occurs in plasma membrane receptors. Hydrocortisone replacement therapy in these animals lowers the receptor number in the both fractions. Hydrocortisone-induced hypercorticism does not change 125I-insulin binding by nuclear envelope but decreases its binding (accounted for the number of receptors and affinity) by the plasma membrane. Under hyperadrenalinemia the number of receptors decreases in the both subcellular fractions. The results suggest no independent regulation of insulin receptors on the surfaces of nuclei and cells.

[Specific 125I-insulin binding by hepatocyte plasma membranes and nuclear envelopes in experimental hyperinsulinemia, alloxan diabetes and starvation]. / Spetsificheskoe sviazyvanie 125I-insulina plazmaticheskimi membranami i obolochkami iader gepatotsitov pri éksperimental'noi giperinsulinemii, alloksanovom diabete i golodanii.

A comparative study has been carried out of the insulin-receptor interaction in rat liver plasma membrane and nuclear envelope under experimental hyperinsulinemia (14 days) and hypoinsulinemic states (3 days alloxan diabetes, 2 days fasting, and joint action of these factors). In all the cases, including additivity of the receptorotropic effects of diabetes and fasting, the changes in levels of specific binding of 125I-insulin and indices, reflecting receptor number, were unidirectional both in the plasma membrane and nuclear envelope. Some divergences were observed for indices reflecting the affinity changes of the receptors from different sources. It is suggested that in insulin-induced regulation of insulin receptor number the relationship between intracellular membrane receptors and receptors in the plasma membrane and nuclear envelope is the same.

[Ornid but not atropine abolishes the insulin receptor reaction of fat and liver plasma membranes to fasting and hyperinsulinemia]. / Ornid, no ne atropin, snimaet reaktsiiu insulinovykh retseptorov zhirovykh i pechenochnykh plazmaticheskikh membran na golodanie i giperinsulinemiiu.

In rats, atropine and saline did not affect the response of insulin receptors increased by fasting but decreased it under condition of hyperinsulinemia in fat and hepatic plasma membranes Ornid abolished the response of the membrane insulin receptors both in fasting and hyperinsulinemia. The data obtained confirm the participation of the sympathetic system in the insulin receptors regulation.

[Inhibition of the insulin receptor activity of fat cell plasma membranes in rats with hyperadrenalinemia]. / Ugnetenie aktivnosti insulinovykh retseptorov plazmaticheskikh membran zhirovykh kletok u krys pri giperadrenalinemii.

Insulin receptor interaction was examined in fatty plasma membranes of rats given adrenaline hydrochloride for 6 days in a dose producing a 10-20-fold increase in adrenaline excretion. A significant reduction in specific 125I-insulin binding was discovered in the presence of the lowered concentration of blood plasma immunoreactive insulin versus the control. Analysis made according to Skatchard, Meyts and Roth indicates that the reduced specific binding of 125I-insulin is accounted for by the decreased affinity and number of insulin binding sites and, to a less degree, by the increased negative cooperativity.

[Effect of adrenalectomy and hydrocortisone on insulin receptors of rat fat cell plasma membranes]. / Vliianie adrenaléktomii i gidrokortizona na insulinovye retseptory plazmaticheskikh membran zhirovykh kletok krysy.

Specific insulin binding with insulin receptors of fatty acid plasma membranes is established to be intensified 10 days after adrenalectomy in rats due to an increase in the receptor number. Hydrocortisone administered for 10 days in a dose of 1 mg per 100 g of body mass to adrenalectomized rats for substitution therapy and to intact ones for 14 days in a dose of 5 mg per 100 g of body mass to induce hypercorticism inhibits the expression of insulin receptors of fatty plasma membranes because of their number and affinity for the hormone. The data obtained confirm information on an inhibitory effect of glucocorticoids on the expression of insulin receptors.

[Insulin receptors of fat cells plasma membranes in patients with diabetes mellitus with various insulin requirements]. / Insulinovye retseptory plazmaticheskikh membran zhirovykh kletok u bol'nykh sakharnym diabetom s razlichnoi potrebnost'iu v insuline.

Maximum specific and non-specific 125I-insulin binding by the fatty cell plasmatic membranes was determined in 10 insulin-treated patients with diabetes mellitus and insulin receptors were studied in 5 of them by means of saturation analysis. It was shown that the concentration of insulin receptors in the patients under examination was lowered and their affinity to insulin and negative cooperating interaction between them remained unchanged comparatively to those of patients without endocrine pathology. There was no correlation between a daily dose of insulin injected and the value of the maximum specific 125I-insulin binding.

[Effect of adrenalectomy and hydrocortisone on the status of the insulin receptors in the plasma membranes of the rat liver]. / Vliianie adrenaléktomii i gidrokortizona na sostoianie insulinovykh retseptorov v plazmaticheskikh membranakh pecheni krys.

A study was made of the effect of adrenalectomy (10 days after operation), administration of hydrocortisone to adrenalectomized rats (1 mg per 100 g bw a day for 10 days, starting from the 1st day after operation), and hydrocortisone-induced hypercorticoidism (5 mg per 100 g bw a day for 14 days) on the parameters of insulin receptors of liver plasma membranes. Depiction of the obtained data in the form of the Sketchard-Meites-Rose dependencies has shown that adrenalectomy increases the concentration and affinity of the receptors for the hormone. Administration of hydrocortisone to adrenalectomized rats reduces the concentration of the receptors, while hypercorticoidism decreases their affinity without affecting the concentration. The data obtained suggest an indirect action of glucocorticoids on the insulin receptors in liver plasma membranes.

[Effect of experimental hyperinsulinemia on the insulin receptor activity of the plasma membranes of the fatty and liver tissue from rats with disturbed liver innervation]. / Vliianie ekaperimental'noi giperinsulinemii na aktivnost' insulinovykh retseptorov plazmaticheskikh membran zhirovoi i pechenochnoi tkanei u krys snarushennoi innebratsiei pecheni.

A study was made of the effect of experimental hyperinsulinemia, caused by daily administration of the increasing doses of a crystalline insulin-zinc suspension (up to 6 Units per animal) during 14 days, on the parameters of 125I-insulin binding by the insulin receptors of plasma membranes of adipose and liver tissues of intact rats and those with disturbed liver innervation. In intact rats, hyperinsulinemia led to the fall of the concentration of the insulin receptors and their affinity for insulin in the membranes of both tissues. In rats with disturbed liver innervation, analogous changes were observed for the receptors of adipose tissue, whereas the parameters of the receptors of liver were unchanged under the effect of hyperinsulinemia. It is concluded that nerve fibers that innervate the liver take part in the regulation of activity of the insulin receptors.