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Biomedical subjects

K Hecht

Publications and source records attributed to K Hecht.

At least 91 records · Page 5Linked to original sources
PubMed1976

[Hormonal stimulation of adenosine 3',5'-cyclic monophosphate formation in cell-free particles and intact cells of smooth muscle in the aorta and femoral artery of rats during immubilization stress].

The ability of adrenaline and histamine to stimulate the formation of cyclic AMP was investigated in broken cell preparation and intact cells of smooth muscle of the aorta and femoral artery of rats which had been subjected to daily intermittent immobilization for 1, 3, and 17 weeks. It was found that this type of stress led to an instability of the blood pressure which was associated with an increase in the sensitivity of adenylate cyclase in the broken cell preparations from the arteries to adrenaline and histamine and with a heightened cyclic AMP response to the two hormones in the intact arterial smooth muscle cells. The sensitivity of cardiac adenylate cyclase for adrenaline remained unchanged.

Adenylyl Cyclases↗
PubMed1976

[The significance of stress intensity for the emotional and visceral reactivity, especially for blood pressure regulation].

The influence of light, medium, and heavy chronic stress upon cerebro-visceral functions following 3 and 5 weeks of daily stress exposure was examined. The following results were obtained: Light stress produced no changes of cerebro-visceral functions. Medium stress restricted the learning and memory capacity, increased systolic blood pressure, fasting blood sugar and adrenal weights. The B-cells of the pancreatic islets showed degranulations of varying intensity. Heavy stress diminished the learning and memory capacity, increased adrenal weights and led to hypergranulation of the pancreatic B-cells. Blood sugar and blood pressure values fall within physiological limits. Load tests, however, revealed in these animals symptoms of premorbid states. Since throughout the period of observation, light stress stablized the regulation processes, medium stress induced early stages of pathological processes, and heavy stress caused premorbid states, no linearity could be established between the load intensity and the changes of cerebro-visceral functions.

Adrenal Glands↗
PubMed1976

[Correlations between hippocampus function and stressed learning and their effect on cerebro-visceral regulation processes].

43 male albino rats were investigated to find out what are the effects of bilateral exclusion of pes hippocampus structures upon the development of arterial hypertension released by learning stress exposure. The following results were obtained: 5 weeks of stress exposure (learning load and heavy learning load) caused disturbances of information-processing events of the central nervous system in all the animals with hippocampal lesions. Systolic blood pressure values, fasting blood sugar values, and adrenal weights fall within the physiological range. The B-cells of the pancreatic islets show hypergranulation. Functional tests of the blood pressure under exercise load, and of blood sugar under glucose load revealed normal reactions in animals with hippocampal lesions. In animals with intact brains the same stress exposure caused pathologic malfunctioning (under learning stress) or even premorbid states. The results being considered in relation to the pathogenesis of arterial hypertension show that the exclusion of circumscribed areas of the hippocampus prevents the development of permanent, stress-induced emotional excitations spreading into the viscerum.

Animals↗
PubMed1976

[The effect of lesions of the caudate nucleus on the development of hypertonic blood pressure dysregulation due to learning stress].

Male albino rats were used to study the effect of excluding the nucleus caudatus upon the development of a hypertensive dysregulation induced by the load of learning (stress). A 3-week stress exposure considerably restricted learning and memory processes in all the animals with nucleus caudatus lesions. Systolic blood pressure values and adrenal weights were within the physiological range. In animals with intact brains, the same stress exposure caused a certain restriction of learning processes and a rise of blood pressure and adrenal weight. The results described here show that the lesions of nucleus caudatus structures, similar to the exclusion of circumscribed areas of the hippocampus and the reticular formation, prevents spreading of stress-induced emotional excitation into visceral functional areas.

Animals↗
PubMed1976

[Learning and chronobiological regulation following experimental damage to the coronary-artery wall of albino rats].

Forty male albino rats were used to study the relationship between experimentally (concentrated hydrochloric acid) produced local structural changes of the coronary artery wall and central nervous information processing and chronobiological events, respectively. The alterations of the coronary arteries caused by this treatment did not produce infarction but initiated on the whole length of the arterial branch proliferative processes that are complete within 12 weeks following the intervention. Central nervous information processing and chronoregulatory processes showed, immediately after exposure to hydrochloric acid, pronounced malfunctions followed by a stage of hyperreactivity (4 weeks following the damage). At 8 weeks from the intervention, the parameters of information processing and chronobiological events of the CNS again equalled the control values. Since the central nervous functions were back to normal earlier than the structural alterations, the results are interpreted as reflecting CNS-controlled interactions between the complex of visceral afference and efference, the regulation of which is determined by the CNS after coronary damage in such a way as to restore the adaptational capacity of the organism by a predominance of sanogenetic processes.

Animals↗
PubMed1975

[Biphasic effect of angiotensin II on conditioned reflectory reaction patterns in albino rats].

40 male albino rats were used to investigate the influence of one single i. v. dose of 10 ng/kg Angiotensin II upon established and stabilized conditional-reflectory response pattern (two-dimensional conditional-reflectory decision process and periodicities of conditional-reflectory processes). At normotonous blood-pressure values, Angiotensin II exerted a biphasic action on the conditional-reflectory response pattern. In the first phase of action (up to 30 min after injection) there prevailed centralnervous inhibition processes, while the second phase of action (30-70 min after injection) was marked by a general centralnervous excitation, which is reflected by extremely short times of response, and a pronounced sensitivity to optic, acoustic and tactile stimuli. The decision capacity of the animals was considerably reduced in both phases. The periodicities of conditional-reflectory processes (duration of periods in the minute range) are strongly disturbed in the first phase of action, and tend to normal in the second phase. Furthermore, Angiotensin II was found to have a selective, hierarchically ordered influence with regard to the duration and intensity of action. Thus, the information processing activity of the CNS underwent most pronounced changes. The centralnervous regulatory functions were less affected; the blood pressure regulation showed little and transient influence by Angiotensin II. In the discussion, the neurotropic and algogenic action of Angiotensin II, and the relation of the octapeptide effect with pathogenetic mechanisms of experimental neurotically induced hypertonia are dealt with.

Angiotensin II↗
PubMed1975

[Ultrastructural observations in the lamina elastica interna and adjacent tissue regions of the arterioles of rats impaired by hypertension of different pathogenesis (author's transl)].

QUESTION: The experiments aim to answer the question whether early changes in the lamine elastica interna of peripheral arteries causing consecutive plasmatic insudation of the vascular wall ("plasmatic vasculosis" according to GOLDBLATT) can be visualized by electron microscopy. Demonstration of early lesions in the elastica interna would facilitate the interpretation of structural changes in the arterial periphery during acute hypertension and its consecutive symptoms. MATERIALS AND METHODS EXPERIMENTAL ANIMALS: 37 male albino rats, 3 to 4 1/2 months of age, body weight: 250 to 350 g. Controls 19 rats of similar age and body weight, 6 of which were injected the carrier substance of depot angiotensin PVP (VEB Berlin-Chemie). The test arrangement is represented in table 1. 3 hours to 10 weeks after starting the treatment different groups of experimental animals were sacrificed. Several animals were administered tracer substances for demonstration of early disturbances in permeability (ferritin: 20 to 40 mg per 100 g body weight, 3 to 60 min ante mortem; charcoal: 10 to 20 mg per 100 g body weight diluted in 1.5 to 3.0 ml of distilled water 15 to 30 min ante mortem). Electron microscopic investigations were carried out in arterioles of 15 mum to 100 mum in diameter which had been removed from the stomach, colon, jejunum, pancreas, mesenterium, partially from the brain and heart, in cases also from the lungs. For comparable specimens with respect to early ultrastructural changes only such tissue sections were selected that were light microscopically free from lesions. Preparation for electron microscopy was done in the common way. RESULTS: in light microscopically intact arterioles of all 3 groups (see table 1) the well-known disturbances of intimal permeability were electron microscopically observed already after 3 hours of experimentation. These changes occur always in the splanchnic organs and in the heart. Contrarily they do not regularly occur in the brain. In rats impaired by experimental neurosis (group III) the disturbances in perfusion of the intima recede, the consequences of enhanced metabolix activity in the media predominate in the sence of a "non-specific mesenchymal reaction" (HAUSS et al. 1964). However, it should be taken into consideration that this enhanced metabolic activity and cell proliferation may actually warrant the relative stability of the elastic barrier observed in this experimental group. In rats with nephrogenic and angiotensin-induced hypertension the experiments result in principally similar lesions of the lamina elastica interna originating from the vascular lumen. The diverging results in rats impaired by neurotically conditioned disturbed regulation of the blood pressure speak in favor of a prevailing reaction of the media at well preserved structures of the lamina elastica interna.

Angiotensin II↗
PubMed1975

[Effect of angiotensin II on the conditional relfex response patterns of neurotic albino rats].

The effect of one single dose of 10 ng Angiotensin II/kg body weight upon affirmed conditional-reflectory response patterns (two-dimensional conditional-reflectory decision process and periodicities of conditional-reflectory processes) was studied in 50 male albino rats in which a neutrotically induced hypertensive blood pressure regulation had been elicited by stress exposure for 135 days. Contrary to healthy animals in which Angiotensin II was demonstrated to act in a biphasic manner, the neurotic animals revealed a monophasic action manifesting itself by a generalized centralnervous excitation. It was noticed, furthermore, that the information processing and regulatory processes of the CNS are considerably disturbed. The chronically hypertensive systolic blood pressure values of neurotic animals, like in healthy ones, show a brief, transient rise immediately following administration of Angiotensin II. These results are not only another proof of a neurotropic component of Angiotensin II action, but they show also that this action allows one to judge the state of disturbed nervous functions. The correlation of the neurotropic effect of Angiotensin II with pathogenetic mechanisms of experimental neurotically induced hypertension is discussed.

Angiotensin II↗
PubMed1975

[Significance of different social factors active in the course of ontogenesis, for the effectiveness of chronic stress influences upon cerebro-visceral regulation processes of albino rats].

Fifty male albino rats were used to study how social factors (animals kept in large groups with playing-cage character, or in social isolation by solitary maintenance) are reflected in the responsiveness of cerebro-visceral regulation processes to chronic stress exposure. The following results were obtained: Animals kept from the 12.-30. week of life in social companionship and, additionally, exposed to chronic stress influences, proved to be greatly resistant to permanent load. This effect is referred to the rich supply of social afferentations and to the pronounced stimulation of proprioreceptive reafference as a result of social communication and motor activity. Animals kept, after preceding large-group maintenance, in social isolation from the 17.-30. week and simultaneously being exposed to the same stress influence as the animals in the playing cage, showed symptoms of an early stage of neurotically induced, arterial hypertension. Here, the chronic lack of socially determined, adequate environmental afferentation and of proprioreceptive reafference, as was typical of solitary maintenance, proved to be a factor enhancing the pathological predisposition of the organism under extreme environmental conditions.

Adaptation, Physiological↗
PubMed1975

Impacts of environmental stress exposure on central nervous functional patterns. A quantitative approach to evoked potential data.

Albino rats and rhesus monkeys with chronically implanted electrodes in cortical and subcortical, vasomotory and emotionally relevant brain regions were subjected to psycho-nerval stress (short-term stressful CR learning experiments on rats, long-term environmental stress with disturbances of the diurnal rhythm and social hierarchy on rhesus monkeys). Applying average computer techniques and discriminance analyses to evoked potentials (average evoked potentials = AEP to standardized optic-acoustic test stimuli) we were able to objectify the effect of different stress categories on central nervous functional patterns. These phenomena of electrical activity of the CNS proved to be extremely responsive to the stress exposure (avoidance conditioned learning experiments or socio-emotional overstrain). Under moderated stress (CR phases of acquisition and stabilization), time-space patterns of a primary facilitation of AEP could be established, expressing an improved energetic capacity of the CNS (adaptive effect). On the other hand, there was a generalized impairment of bioelectric information processing in temporal correlation with an increase in psycho-nervous stress exposure to rats (CR phases of differentiation). During long-term socio-emotional stress exposure of rhesus monkeys the highly significant changes of AEP-patterns (increasing fall short of the set point of the bioelectric level of activity with segmental differences in the multiphasic evoked potential) are to be interpreted as maladaptive processes in central nervous function under long lasting high stress conditions.

Adaptation, Physiological↗