Renin-Angiotensin System - Past, Present and Future

Exploring the contractile activity of smooth muscle segments isolated from various organs of healthy animals and animals with experimentally induced diabetes, she obtained original data about angiotensin II-induced force and time parameters. For the first time, she established the effect of ghrelin on angiotensin II-provoked contraction of the urinary bladder. Original data on the role of both types of angiotensin receptors for the contractile activity of the various segments of the gastrointestinal tract and bladder were obtained. By applying specific software for force and time parameter analysis, the contribution of different types of angiotensin receptors on muscle contractility has been shown. The new methodology was used to analyze the data obtained during the registration of smooth muscle relaxation activity, which allows the determination of not only the magnitude of the mechanical response but also the parameters related to the time and speed of the contractions. Plasma renin activity models have been developed using mathematical approaches to predict the effect of different drug doses on the behavior of the system

Influence of Captopril Treatment of Plasma Renin Activity � Mathematical Model

A model of the dynamics of plasma renin activity under the influence of various doses of captopril is formulated. The influence of captopril on renin angiotensin system is different from the effects of the other studied drugs nifedipine and nicardipine. Captopril inhibits the feedback in renin-angiotensin system and the upward trend of the renin activity is a proportional of the intrinsic growth rate. This dependence can be described using a modified Verhulst logistic function is proposed. The model is identified using the Korelia-Dynamics program. As optimization method for data identification a cyclic coordinate descent method is used. The residuals between the experimental data and the identified model are minimized applying least square or uniform fitting. The model allows prediction the effects of different captopril doses and permits the researcher to study the behavior of the renin angiotensin system under variety of conceivable conditions

Influence of Captopril Treatment of Plasma Renin Activity � Mathematical Model

A model of the dynamics of plasma renin activity under the influence of various doses of captopril is formulated. The influence of captopril on renin angiotensin system is different from the effects of the other studied drugs � nifedipine and nicardipine. Captopril inhibits the feedback in renin-angiotensin system and the upward trend of the renin activity is a proportional of the intrinsic growth rate. This dependence can be described using a modified Verhulst logistic function is proposed. The model is identified using the Korelia-Dynamics program. As optimization method for data identification a cyclic coordinate descent method is used. The residuals between the experimental data and the identified model are minimized applying least square or uniform fitting. The model allows prediction the effects of different captopril doses and permits the researcher to study the behavior of the renin angiotensin system under variety of conceivable conditions

Distribution of ghrelin-positive mast cells in rat stomach

It is known that the gastrointestinal peptide hormone ghrelin is expressed in human and rodent B lymphocytes, T lymphocytes, monocytes and natural killer cells. However, there are no data about ghrelin expression by mast cells. These facts, as well as the common progenitor cells of mast cells and the above-mentioned immune cells, motivated us to undertake the current work in order to prove that like other granulocytes, rat gastric mast cells are capable of immunohistochemical expression of ghrelin. Gastric wall sections of Wistar rats were studied immunohistochemically for detection of ghrelin and tryptase and histochemically for toluidine blue in order to identify ghrelin-positive mast cells as well as to establish their localization and distribution. Results showed that mast cell granules expressed ghrelin. The ghrelin-positive mast cells were the least numerous as compared to tryptase-positive mast cells and toluidine blue-positive mast cells. Based on the observed expression of ghrelin in granules of mast cells localized in the rat gastric wall, we suggested that this type of cell can be regarded as an important source of ghrelin and suggested that ghrelin may exert different physiological functions, such as regulation of muscular, epithelial and glandular functions