Efficacy of the self-regulation mechanisms of the heart contractile function in adaptation to great and excessive physical loads

Upon adaptation to large physical loading, intensity of the efficacy of self-regulation mechanisms of the heart contractile function increases, but under overloading influence it decreases.     

Central hemodynamics and motor activity in 11- to 12-year-old girls under different conditions of school instruction

The left ventricular power (LVP), stroke volume (SV), cardiac output (Q), systolic blood pressure (BP_s), and the overall physical activity of schoolgirls attending gymnasium classes with in-depth instruction in specific subjects were lower than in those attending general education classes with the standard curriculum. There were no differences in heart rate (HR), specific peripheral resistance (SPR), or diastolic blood pressure. The stroke index (SI) and cardiac index (CI) were, respectively, moderately and strongly correlated with the degree of motor activity.     

Effect of adaptation to physical loading on the adrenoreactivity of the isolated rat atrium

The experiments on the isolated atria of rats, previously adapted to swimming exercises, have established a significant decrease in the heart rate and an increase in positive inotropic effect of noradrenaline (4 X 10(-7) and 6 X 10(-7) M). After beta-adrenoceptor blockade with propranolol (2 X 10(-6) M) the inotropic effect of an alpha-adrenoceptor agonist mezaton on the isolated atrium of the adapted rats was greater than in nonadapted controls.     

Wave exposure shapes reef community composition and recovery trajectories at a remote coral atoll

In a time of unprecedented ecological change, understanding natural biophysical relationships between reef resilience and physical drivers is of increasing importance. This study evaluates how wave forcing structures coral reef benthic community composition and recovery trajectories after the major 2015/2016 bleaching event in the remote Chagos Archipelago, Indian Ocean. Benthic cover and substrate rugosity were quantified from digital imagery at 23 fore reef sites around a small coral atoll (Salomon) in 2020 and compared to data from a similar survey in 2006 and opportunistic surveys in intermediate years. Cluster analysis and principal component analysis show strong separation of community composition between exposed (modelled wave exposure > 1000 J m⁻³) and sheltered sites (< 1000 J m⁻³) in 2020. This difference is driven by relatively high cover of Porites sp., other massive corals, encrusting corals, soft corals, rubble and dead table corals at sheltered sites versus high cover of pavement and sponges at exposed sites. Total coral cover and rugosity were also higher at sheltered sites. Adding data from previous years shows benthic community shifts from distinct exposure-driven assemblages and high live coral cover in 2006 towards bare pavement, dead Acropora tables and rubble after the 2015/2016 bleaching event. The subsequent recovery trajectories at sheltered and exposed sites are surprisingly parallel and lead communities towards their respective pre-bleaching communities. These results demonstrate that in the absence of human stressors, community patterns on fore reefs are strongly controlled by wave exposure, even during and after widespread coral loss from bleaching events.

     

Teleconnections reveal that drivers of inter-annual growth can vary from local to ocean basin scales in tropical snappers

Coral Reefs - Individual growth rate is one of the key traits that determine the productivity of populations. Chronological approaches that relate time series of growth and climate information...     

Cardiovascular, impllent and sensory reactions of various specializations athletes on vestibular irritation

It is marked in the article that the average value of heart chronotropic reaction of athletes to vestibular irritation from different positions of a head and duration of sensory reactions are inversely related to exercise saturation of every kind of sport by angular accelerations. Severity of the systolic blood pressure reaction of various specializations athletes does not differ. Strength and frequency of hand movements of athletes increase on the background of the rotational load, and accuracy of the given efforts declines, but these changes are not related to their specialization. In the controls these rates are reduced, though their accuracy of effort is much greater than athlete's accuracy efforts.     

Mechanisms of self-regulation of myocardial contractile function during hypokinesia and muscle training

This article analyzes the literature devoted to the role of the myocardial contractile apparatus in the regulation of cardiac pump function during hypokinesia, moderate and excessive physical exercises. These data indicate that moderate exercises increase the role of myocardial contractile apparatus, thereby efficiency of cardiac and extracardiac mechanisms for its regulation increase. Excessive loads increase adrenergic inotropic effects on the myocardium in combination with a reduction of the contribution of its contractile apparatus in a common set of regulatory influences on cardiac pump function. Weakening of self regulation mechanisms is typical for the regime of hypokinesia also. However, in the latter case the enhancement of adrenergic inotropic effects is absent.     

The contractile function and electrical stability of the heart in different regimens of physical exercise

Adaptation to moderate duration of physical loading causes identical levels of increase in threshold fibrillation of ventricles in wide range of their intensity. Rise of contractile heart function increases with prolonged adaptation regimen of heavy loading exercise. With hypokinesia and excessive physical load the sinking of threshold of fibrillation of ventricles occurs in lacking of alterations and with high contractile function of the heart respectively.