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32. LVV-Hemorphin-7 Lowers Blood Pressure in Spontaneously Hypertensive Rats: Radiotelemetry Study

Creator:
Čejka, J., Železná, B., Velek, j., Zicha, J., and Kuneš, J.
Type:
article, model:article, and TEXT
Subject:
Hemorphin, Blood pressure, Heart rate, Hypertension, and Rat
Language:
English
Description:
Cardiovascular effects of LVV-hemorphin-7, a member of the family of fragments from β-chain of human or bovine hemoglobin, were studied in conscious spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats by radiotelemetry. Intraperitoneal injection of hemorphin in a dose of 100 g/kg significantly decreased blood pressure in SHR, whereas negligible effect was seen in normotensive WKY rats. Blood pressure changes were accompanied by reduction of heart rate. In conclusion, a direct effect of LVV-hemorphin-7 on blood pressure was demonstrated in SHR. These biologically active peptides could be involved in blood pressure regulation especially in hypertensive rats, but the precise mechanism should be elucidated.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

33. Metabolism of Bromide and Its Interference with the Metabolism of Iodine

Creator:
Pavelka, S.
Type:
article, model:article, and TEXT
Subject:
Bromide, Iodide, Metabolism, Rat, and Thyroid
Language:
English
Description:
The present knowledge about the metabolism of bromide with respect to its goitrogenic effects, including some conclusions drawn from our recent research on this subject, is reviewed. Firstly, the biological behavi or of bromide ion is compared with that of chloride and iodide. Secondly, the details about distribution and kinetics of bromide ions in the body and in 15 different organs and tissues of the rat are given. Significant correlation between the values of the steady-state concentration of bromide in the respective tissue and of the corresponding biological half-life was found in most tissues examined. A remarkably high concentration of radiobromide was found in the skin, which represents, due to its large mass, the most abundant depot of bromide in the body of the rat. Thirdly, the effects of excessive bromide on the rat thyroid are summarized, along with the interference of exogenous bromide with the whole-body metabolism of iodine. It is suggested that high levels of bromide in the organism of experimental animals can influence their iodine metabolism in two parallel ways: by a decrease in iodide accumulation in the thyroid and skin (and in the mammary glands in lactating dams), and by a rise in iodide excretion by kidneys. By accelerating the renal excretion of iodide, excessive bromide can also influence the pool of exchangeable iodide in the thyroid. Finally, our recent results concerning the influence of high bromide intake in the lactating rat dam on iodine and bromide transfer to the suckling, and the impact of seriously decreased iodine content and increased bromide concentration in mother’s milk on the young are discussed. We must state, however, that the virtue of the toxic eff ects of excessive bromide on the thyroid gland and its interference with the biosynthesis of thyroid hormones, as well as the exact mechanism of bromide interference with postnatal developmental processes remains to be elucidated.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

35. Negative Inotropic Effect of Insulin in Papillary Muscles From Control and Diabetic Rats

Creator:
Švíglerová, J., Kuncová, J., and Štengl, M.
Type:
article, model:article, and TEXT
Subject:
Insulin, Rat, Heart, Contraction, and Diabetes
Language:
English
Description:
The inotropic effects of insulin in the rat heart are still incompletely understood. In this study, the effects of insulin on cardiac contraction were studied in right ventricular papillary muscles from both control rats and rats with chronic diabetes (lasting 16 weeks). Diabetes was induced by the application of streptozotocin (STZ) and the development of diabetes was documented by increased levels of blood glucose, by reduction in body weight and by decreased plasma concentrations of insulin. The contraction was significantly smaller in diabetic rats. Insulin (80 IU/l) reduced the contraction force in both control and diabetic groups. The post-rest potentiation of contraction was not influenced by insulin in control rats, but insulin increased it in diabetic rats. The negative inotropic effect of insulin was preserved in the presence of cyclopiazonic acid (3 μmol/l), a blocker of sarcoplasmic reticulum (SR) Ca2+ pump, in both control and diabetic groups. In contrast, the negative inotropic effect of insulin was completely prevented in the presence of nifedipine (3 μmol/l), a blocker of L-type Ca2+ current. We conclude that insulin exerts a significant negative inotropic effect in rat myocardium, both control and diabetic. This effect is probably related to processes of SR Ca2+ release triggering, whereas SR Ca2+ loading is not involved.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

36. Ontogenetic development of sensitivity of the cerebral cortex to an Antagonist of GABAA receptor bicuculline

Creator:
Pavel Mareš, Klára Bernášková, and Hana Kubová
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
fyziologie člověka, human physiology, Cerebral cortex, Rat, Postnatal development, Epileptic phenomena, Bicuculline, 14, and 612
Language:
English
Description:
Local application of four concentrations of bicuculline methiodide (a specific antagonist of GABAA receptors) was used to study a sensitivity of somatosensory cortex in four age groups of immature rats with implanted electrodes. Presence and latencies of two epileptic phenomena (focal discharges and seizures) were evaluated. Focal discharges exhibited moderate tendency to a decrease of sensitivity to bicuculline methiodide with maturation. Concentration-effect relation of incidence of focal discharges was observed only in 7- and 12-day-old but not in older animals. Results with incidence and latencies of seizures did not show relations to age or concentration of bicuculline. Neither of the epileptic phenomena can be used as a reliable index of cortical maturation., P. Mareš, K. Bernášková, H. Kubová., and Seznam literatury
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

37. Pattern of Right Ventricular Pressure Fall and Its Modulation by Afterload

Creator:
Correia-Pinto, J., Henriques-coelho, T., Magalhaes, S., and Leite-Moreira, A.F.
Type:
article, model:article, and TEXT
Subject:
Right ventricle, Ventricular pressure fall, Relaxation time constant, and Rat
Language:
English
Description:
Pattern of right ventricular pressure (RVP) fall and its afterload dependence were examined by analyzing ventricular pressure curves and corresponding pressure‑dP/dt phase planes obtained in both ventricles in the rat heart in situ. Time and value of dP/dtmin, and the time constant τ were measured at baseline and during variable RV afterload elevations, induced by beat-to-beat pulmonary trunk constrictions. RVP and left ventricular pressure (LVP) decays were divided into initial accelerative and subsequent decelerative phases separated by corresponding dP/dtmin. At baseline, LVP fall was decelerative during 4/5 of its course, whereas only 1/3 of RVP decay occurred in a decelerative fashion. During RV afterload elevations, the absolute value of RV-dP/dtmin and RV-τ increased, whilst time to RV‑dP/dtmin decreased. Concomitantly, the proportion of RVP decay following a decelerative course increased, so that in highly RV afterloaded heartbeats RVP fall became more similar to LVP fall. In conclusion, RVP and LVP decline have distinct patterns, their major portion being decelerative in the LV and accelerative in the RV. In the RV, dP/dtmin, τ and the proportional contribution of accelerative and decelerative phases for ventricular pressure fall are afterload-dependent. Consequently, τ evaluates a relatively much shorter segment of RVP than LVP fall.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

38. Photoperiodic regulation of PER1 and PER2 protein expression in rat peripheral tissues

Creator:
Bendová, Z. and Sumová, A.
Type:
article, model:article, and TEXT
Subject:
Circadian rhythms, Peripheral tissue, PER proteins, and Rat
Language:
English
Description:
Circadian oscillations in biological variables in mammals are controlled by a central pacemaker in the suprachiasmatic nuclei (SCN) of the hypothalamus which coordinates circadian oscillators in peripheral tissues. The molecular clockwork responsible for this rhythmicity consists of several clock genes and their corresponding proteins that compose interactive feedback loops. In the SCN, two of the genes, Per1 and Per2, show circadian rhythmicity in their expression and protein production. This SCN rhythmicity is modified by the length of daylight, i.e. the photoperiod. The aim of the present study was to find out whether profiles of PER1 and PER2 proteins in peripheral organs are also affected by the photoperiod. Rats were maintained under a long photoperiod with 16 h of light and 8 h of darkness per day (LD 16:8) and under a short, LD 8:16, photoperiod. The PER1 and PER2 daily profiles were measured in peripheral organs by Western blotting. The photoperiod affected significantly the PER1 profile in livers and the PER2 profile in lungs and hearts. In lungs, PER2 in the cytoplasmic, but not in the nuclear fraction, was affected significantly. The effect of the photoperiod on PER1 profiles in peripheral organs appears to differ from that in the SCN.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

39. Pinealectomy Increases and Exogenous Melatonin Decreases Leptin Production in Rat Anterior Pituitary Cells: an Immunohistochemical Study

Creator:
Kus, I., Sarsilmaz, M., Colakoglu, N., Kukner, A., Ozen, O.A., Yilmaz, B., and Kelestimur, H.
Type:
article, model:article, and TEXT
Subject:
Leptin, Melatonin, Pinealectomy, Anterior Pituitary, and Rat
Language:
English
Description:
Melatonin, the main hormone of the pineal gland, informs the body about the environmental light and darkness regimen, which in turn contributes to the photoperiodic adaptation of several physiological functions. Leptin, the hormone secreted mainly by adipocytes and some other tissues including the pituitary, informs the brain about the mass of adipose tissue, which plays an important role in energy homeostasis. Melatonin has been shown to decrease circulating leptin levels. It is currently not known whether melatonin has an effect on leptin synthesis in the pituitary. The aim of this study was to immunohistochemically examine the effects of pinealectomy and administration of melatonin on leptin production in the rat anterior pituitary. The pituitary samples obtained from 18 male Wistar rats including sham-pinealectomized, pinealectomized and melatonin-injected pinealectomized groups were immunohistochemically evaluated. Immunostaining of leptin was moderate (3+) in sham-pinealectomized rats, heavy (5+) in pinealectomized rats and low (1+) in melatonin-treated pinealectomized rats, respectively. The present results indicate that pinealectomy induces leptin secretion in anterior pituitary cells, and this increase of leptin synthesis can be prevented by administration of melatonin. Thus, melatonin seems to have both physiological and pharmacological effects on leptin production in the anterior pituitary of male rats.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

40. Risperidone potentiates the sympathetic and hyperthermic reactions induced by orexin A in the rat

Creator:
Monda, M., Viggiano, An., Viggiano, Al., Viggiano, E., and De Luca, V.
Type:
article, model:article, and TEXT
Subject:
Body temperature, Orexin A, Rat, Risperidone, and Sympathetic activity
Language:
English
Description:
This experiment tested the effect of risperidone on the sympathetic and thermogenic effects induced by orexin A. The firing rates of sympathetic nerves to interscapular brown adipose tissue (IBAT), along with IBAT and colon temperatures and heart rate were monitored in urethane-anesthetized male Sprague-Dawley rats before an injection of orexin A (1.5 nmol) into the lateral cerebral ventricle and over a period of 2 hours after the injection. The same variables were monitored in rats with an intraperitoneal administration of risperidone (50 mg/kg bw), injected 30 min before the orexin administration. The results show that orexin A increases the sympathetic firing rate, IBAT, colonic temperatures and heart rate. This increase is enhanced by the injection of risperidone. These findings suggest that risperidone elevates the responses due to orexin, probably through an involvement of serotoninergic and dopaminergic pathways, which are affected by risperidone. Furthermore, we suggested the name "hyperthermine A" as additional denomination of "orexin A" by considering the strong influence of this neuropeptide on body temperature.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public