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Start Over Coverage 405-414

1. Bifurcations in the two imaginary centers problem

Creator:
Chiralt, Cristina, Campos, Beatriz, and Vindel, Pura
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
bifurcation, topological configuration, and orbital structure
Language:
English
Description:
In this paper we show that, for a given value of the energy, there is a bifurcation for the two imaginary centers problem. For this value not only the configuration of the orbits changes but also a change in the topology of the phase space occurs.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2. Contribution of selected vasoactive systems to blood pressure regulation in two models of chronic kidney disease

Creator:
Drábková, Natálie, Hojná, Silvie, Zicha, Josef, and Vaněčková, Ivana
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
hypertension, chronic kidney Disease, vasoactive systems, partial nephrectomy, and goldblatt hypertension
Language:
English
Description:
It is generally accepted that angiotensin II plays an important role in high blood pressure (BP) development in both 2-kidney-1- clip (2K1C) Goldblatt hypertension and in partial nephrectomy (NX) model of chronic kidney disease (CKD). The contribution of sympathetic nervous system and nitric oxide to BP control in these models is less clear. Partial nephrectomy or stenosis of the renal artery was performed in adult (10-week-old) male hypertensive heterozygous Ren-2 transgenic rats (TGR) and normotensive control Hannover Sprague Dawley (HanSD) rats and in Wistar rats. One and four weeks after the surgery, basal blood pressure (BP) and acute BP responses to the consecutive blockade of renin-angiotensin (RAS), sympathetic nervous (SNS), and nitric oxide (NO) systems were determined in conscious rats. Both surgical procedures increased plasma urea, a marker of renal damage; the effect being more pronounced following partial nephrectomy in hypertensive TGR than in normotensive HanSD rats with a substantially smaller effect in Wistar rats after renal artery stenosis. We demonstrated that the reninangiotensin system does not play so fundamental role in blood pressure maintenance during hypertension development in either CKD model. By contrast, a more important role is exerted by the sympathetic nervous system, the activity of which is increased in hypertensive TGR-NX in the developmental phase of hypertension, while in HanSD-NX or Wistar-2K1C it is postponed to the established phase. The contribution of the vasoconstrictor systems (RAS and SNS) was increased following hypertension induction. The role of NO-dependent vasodilation was unchanged in 5/6 NX HanSD and in 2K1C Wistar rats, while it gradually decreased in 5/6 NX TGR rats.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public