Activity Of Regulatory Systems Research Articles

Sex differences in the fetal programming of hypertension

Numerous clinical and experimental studies support the hypothesis that the intrauterine environment is an important determinant of cardiovascular disease and hypertension. This review examined the mechanisms linking an adverse fetal environment and increased risk for chronic disease in adulthood with an emphasis on gender differences and the role of sex hormones in mediating sexual dimorphism in response to a suboptimal fetal environment. This review focuses on current findings from the PubMed database regarding animal models of fetal programming of hypertension, sex differences in phenotypic outcomes, and potential mechanisms in offspring of mothers exposed to an adverse insult during gestation. For the years 1988 to 2007, the database was searched using the following terms: fetal programming, intrauterine growth restriction, low birth weight, sex differences, estradiol, testosterone, high blood pressure, and hypertension. The mechanisms involved in the fetal programming of adult disease are multifactorial and include alterations in the regulatory systems affecting the long-tterm control of arterial pressure. Sex differences have been observed in animal models of fetal programming, and recent studies suggest that sex hormones may modulate activity of regulatory systems, leading to a lower incidence of hypertension and vascular dysfunction in females compared with males. Animal models of fetal programming provide critical support for the inverse relationship between birth weight and blood pressure. Experimental models demonstrate that sex differences are observed in the pathophysiologic response to an adverse fetal environment. A role for sex hormone involvement is strongly suggested,with modulation of the renin-angiotensin system as a possible mechanism.

Autonomic homeostasis and the specific features of adaptation in children with obesity

The autonomic nervous system and the adaptive mechanisms associated with neuroautonomic cardiac rhythm regulation were studied in obese children. The study covered 187 untreated children aged 6-16 years who had exogenous constitutional (n = 68), diencephalic (n = 20) obesity and hypothalamic puberty syndrome (n = 99). The study was conducted by computer-aided (statistic, spectral) analysis of cardiac rhythm variability. The regulatory system activity index was calculated to assess the tension of adaptive mechanisms. The results were compared with those obtained in 107 apparently healthy children matched by gender and age. The enhanced activity of subcortical nerve centers with a predominance of sympathetic effects was observed in 38.7% of children with puberty obesity. The state of adaptive processes was regarded as a pronounced functional strain, overstrain, and exhaustion of regulatory systems in 31.1% of 6-10-year-old children and 29.5% of 11-16-year-old ones with obesity.

Effect of hypoxia during early organogenesis on cardiac activity and noradrenergic regulation in the postnatal period

Cardiac activity in rats during the postnatal period was studied in vitro and in vivo after exposure of rat pups to antenatal acute hypobaric hypoxia at the stage of organogenesis (day 9-10 of gestation). Cultured cardiomyocytes from rat pups exposed to antenatal hypoxia were characterized by increased rate of contractions and decreased reactivity to norepinephrine. Heart rate elevation, predominance of sympathetic influences on cardiac activity, and significant increase in norepinephrine concentration in the cerebral cortex were found in freely moving animals exposed to antenatal hypoxia. Our results indicate that hypoxia at the stage of organogenesis modulated cardiac activity during the postnatal period, which manifested at the level of effector structures in the heart and activity of regulatory systems.

Dysregulation of apoptotic death in the pathogenesis of virus-induced cytogenetic instability of blood lymphocytes

The cytogenetic status and activity of regulatory systems for stability of the cell genome were evaluated in patients with chronic viral persistence. Hepatitis B and C viruses damage the chromosome apparatus of peripheral blood lymphocytes. Cytogenetic instability of immunocompetent cells during chronic viral infection was associated with inhibition of DNA excision repair system and dysregulation of apoptosis in target cells.

Regulation of the blood circulation system in hypertensive crises using mathematical analysis of the cardiac rhythm

Regulation of the circulatory system in hypertensive crises was studied using mathematical analysis of the cardiac rhythm. The study involved 166 patients from age 29 to 73 years with hypertension stage II–III. The cardiac rhythm variability was assessed for 10-min intervals by parameters of the regulatory system activity (according to R.M. Baevskiiet al.). In hypertensive crisis, the cardiac rhythm variability was decreased, and the activity of systems regulating blood circulation was increased, compared to both the normal and the crisis-free period. Therefore, the determination of parameters of cardiac rhythm variability has an additional diagnostic value. Changes in these parameters in hypertensive crisis depend on the duration of hypertension, the patients’ age, and dysfunction of target organs. Changes in the cardiac rhythm variability persisted after normalization of arterial pressure in the postcrisis period, and this indicates that the patients’ condition was not stabilized during hospital treatment and prolonged supervised hypotensive therapy was required.

Involvement of intracellular regulatory systems in the adaptive effects of transient anoxia in vitro.

The involvement of the calcium and phosphoinositide intracellular regulatory systems in the molecular-cellular mechanisms of adaptation of the brain to hypoxia induced by transient anoxia were studied in slices of rat olfactory cortex. Anoxia lasting 2 min initiated the development of moderate but stable activation of intracellular regulatory systems during the reoxygenation period, with increases in binding of Ca2+ to intracellular hydrophobic domains and increases in the level of polyphosphoinositide metabolism. During this period, cells in the slices released neuromediator factors into the perfusion fluid; transfer of these to recipient slices induced similar changes in the activities of intracellular regulatory system components in the recipient slices. After anoxia lasting 10 min, NMDA-mediated pathogenic hyperactivity of the calcium and phosphoinositide systems developed. Preliminary moderate activation of these systems by transient anoxia or neuromodulator factors released by cells in response to transient anoxia prevented disruption of intracellular regulatory system activity induced by subsequent longer-lasting anoxia.

The effect of sodium intake on maternal milk electrolytes and aldosterone, corticosterone and 18-hydroxydeoxy-corticosterone production in the offspring of rats.

The effects of decreased dietary sodium content during pregnancy and lactation on the activity of adrenal glands of the offspring were investigated. Low salt diet (0.3% of NaCl) increased the aldosterone production in newborn rats, on day 7 and on day 15 decreased the production of 18-hydroxydeoxycorticosterone only; on day 20 only the aldosterone production was increased. Based on the measurements of sodium and potassium concentrations in milk and urine of the offspring, the lasting effects of intrauterine conditions on newborn adrenal gland regulation and the adrenocortical regulatory system activity during the suckling period are discussed. This is done on the basis of literary evidence on amounts of the sodium and potassium required for body mass growth and the observation on the probable shortage of potassium supply in maternal milk towards the end of the suckling period.