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Biomedical subjects

M Poppei

Publications and source records attributed to M Poppei.

At least 37 records · Page 2Linked to original sources
PubMed1976

[Diurnal dynamics of periodicities in conditional-reflex processes in the minute range].

Male adult albino rats living from the 6th week of their lives under conditions of artificial light-dark cycle (16 hrs light, 8 hrs dark) were used to study possible relationships between circadian sensitivity cycles and synchronization of dynamics and the frequency variability of periodicities of reaction times of conditional-reflectory processes with wavelengths in the minute range. The experiments have revealed differences at the time of the activity maximum and minimum of a circadian cycle in the studied parameters of the minute rhythm (mean level of oscillation, mean amplitude, length of period and coupling). In the dark phase (activity maximum) there prevailed an increased level of central-nervous excitation and a tendency towards a higher frequency and diminished coupling of minute periods. In the light phase (activity minumum) the animals showed a balanced level of excitation, reduced frequency and a rigid coupling of periodicities of conditional-reflectory events involved in the process. Relations are shown to exist between central-nervous processes and circadian sensitivity cycles. For the experimental practice it is concluded that the different times of the day should be accounted for in assessing the criteria of minute rhythm and in conditional-reflectory studies in pharmacology and toxicology.

Animals↗
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↗
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

[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↗