[Clotting induction in the mesenterium and erosive stomach mucosa in wistar rats as the result of a catenoidal ultrasonic transducer]. / Tromboobrazuvane v mezenterium i erozirana stomashna ligavitsa na plukh poroda Wistar sled vusdeistvie s katenoidalen ultrazvukov preobrazuvatel.

The ultrasonic transducers and instruments used in surgery operate in the range of 1-10 MHz and release significant heat in the surroundings. They need additional cooling system which significantly raises the cost and impedes the equipment operation. Hemostasis can be successfully achieved by employing ultrasonic transducers that operate in the kilohertz range, avoiding the occurrence of inadmissible tissue overheat outside the area of the transducer performance. The paper presents results of the approbation of the effect of a periodical acoustic signal with frequency of 60 kHz over the erosive stomach mucosa and mesenterium of 28 rats, "Wistar" breed, and the period of tissue exposure is 1-10 min. A transducer-catenoidal semi-wave concentrator that provides maximum emitted power of the ultrasonic wave is used and thermal effects are avoided. It is proved that the use of a powerful and localized ultrasonic signal results in erythrocyte diapedesis and forms microhaemorrhagies together with an out-vessel coagulation in the rat stomach mucosa The tissue damages are strictly limited within the area of the emitter contact and they are subject to control during the ultrasonic performance.

[Interrelationship between the brain and kidney renin--angiotensin systems in combined hypertension: the effect of a central block with saralasin]. / Vzaimootnoshenie mezhdu mozuchnata i bubrechnata reninangio-tenzinovi sistemi pri kombinirana khipertoniia--efekt na tsentralna blokada sus saralazin.

Conditions for Simultaneous stimulation of cerebral and renal renin-angiotension systems (RAS) are created in the examined by us model of combined cerebral and renal ischemic hypertension. As a results of interaction between them the effect o cerebral RAS predominates, since renin concentration in the medulla oblongata is elevated while the renal renin concentration remains unchanged, but the plasma renin activity is lowered. The blocking of the action of cerebral angiotension by the venously administered angiotensin antagonist saralasin does not alter substantially blood pressure, but causes elevation of the renal renin concentration in the ischemic and intact kidney and normalization of plasma renin activity, without affecting the level of sodium and potassium.

[Central and peripheral catecholamines in combined cerebral and renal hypertension]. / Tsentralni i periferni katekholamini pri kombinirana mozuchna i bubrechna khipertoniia.

The present study was carried out on male rats, using three models of experimental hypertension: cerebroischemic, single clamp bilateral and combined, induced by ischemia of the brain and one of the kidneys. The authors determined DA, NA, A in the hypothalamus and medulla oblongata as well as A, NA in plasma in view of the connection between CA (catecholamine) and cerebral and renal renin-angiotensin system (RAS). In rats with cerebral hypertension there was activation of noradrenergic neurons in the hypothalamus and medulla oblongata. There were no changes in the content of A. In rats with renal hypertension the activation of noradrenergic neurons in the hypothalamus was due to exhaustion of NA stores with normal amount of DA, but still the adrenergic neurons were activated. In rats with combined hypertension there was lowering of NA and DA in the hypothalamus, but A was not altered, e.g. the changes, observed singly and in cerebral and renal hypertension were combined. In the three forms of hypertension there were similar changes in medulla oblongata (reduced DA, increased NA and unaltered) and in plasma (A without significant changes). The changes in the level of CA in cerebral and combined hypertension could be explained by a change in the sinocarotid reflex, but in the renal-with the increased level of plasma angiotensin. The authors suggest that the connection between cerebral CA and cerebral RAS is not a direct one and RAS is not directly involved in the inverse interrelationships between cerebral and renal RAS.

[Brain and kidney renin-angiotensin system in rats with simultaneously induced cerebral and renal ischemia]. / Mozuchnata i bubrechnata renin-angiotenzinova sistema pri plukhove s ednovremenno predizvikana mozychna i bubrechna iskhemiia.

The objective of the present work was to study the changes in the brain and renal renin-angiotensin system (RAS) during their simultaneous stimulation by ischemia. Experiments were carried out on the following groups of male normotensive Wistar rats: intact, with brain ischemia, with renal ischemia, with combined brain and renal ischemia. The three ischemic groups of animals had some arterial pressure elevation without reaching hypertensive values. In animals with combined brain and renal ischemia brain renin concentration (BRC) was raised, while plasma renin activity (PRA) was reduced relative to the intact controls, i.e. as in animals with brain ischemia alone. Renal renin concentration (RRC) in the ischemic kidney was at the level of the one in intact animals and in animals with brain ischemia. In the intact contralateral kidney of rats with combined ischemia RRC was reduced relative to the intact kidney of animals with renal ischemia and statistically insignificantly reduced relative to the RRC in intact controls and in animals with brain ischemia. The results of this study showed that inverse ratio between renal and brain RAS exists also in the single clamped--birenal model of hypertension. Interaction between the two RAS is manifested when they both are simultaneously stimulated, with prevalence of the effect of brain RAS, which affects renin secretion in the kidney.

[Determination of the renin concentration in the rat brain using a heterologous substrate]. / Opredeliane na reninova kontsentratsiia v mozuka na plukh s kheterolozhen substrat.

The author introduced a method for determination of brain renin concentration, using the method of Boucher for determination of renin concentration in the kidney and plasma, adapted for brain tissue by Ganten. He defined parameters of enzymic reaction, when the brain renin concentration of a rat was examined by the usage of a nonstandardized dog substrate, prepared by the author. For this purpose she carried out studies on the kinetics of the reaction brain renin of a rat--a dog angiotensinogen. She described the influence of the enzymic substrate concentration and time on the course of the reaction. Furthermore she indicated the preparation of angiotensinogen from a dog plasma, and pointed out its advantages in determining renin in the brain of a rat. The mean value of the brain renin concentration in the rats of the Wistar strain was 140 ng/gm/h.