GABA exhibits depolarizing action in the immature neurons due to high intracellular activity of chloride ions. It is maintained by cation-chloride cotransporter NKCC1 which is present in immature brain. Bumetanide is a specific inhibitor of this cotransporter. We studied possible anticonvulsant activity of bumetanide in pentyl enetetrazol-induced seizures in three age groups of rat pups (7, 12, and 18 days old). Pretreatment with bumetanide (0.2-1 mg/kg i.p.) resulted in dose-dependent decrease of incidence of the tonic phase of generalized tonic-clonic seizures in 12-day-old rats only. No effect was observed in younger and older animals. Higher dose of bumetanide (2.5 mg/kg) did not affect tonic convulsions but, on the contrary, decreased latencies of generalized seizures in 12-day-old animals. Lack of marked anticonvulsant effect is probably due to relative maturity of neurons in the brainstem where the generator of generalized seizures is localized. Age- and dose-specific suppression of the tonic phase needs further analysis. and Obsahuje seznam literatury
The consequences of epileptic seizures related to postictal inhibition in early postictal period include postictal analgesia. We studied this phenomenon over 96 h following flurothyl-induced seizures in adult male Wistar rats. Nociception of control (no seizure) and seizured groups were tested using the plantar and von Frey hair tests. We determined latency of forepaw and hind paw reactions using plantar tests and the number of von Frey hairs reactions. Shortly after seizures, longer plantar test latencies were seen relative to the control group. Before the seizures the plantar test reaction times were significantly shorter in forepaws than in hind paws. The effect disappeared post-seizure and surprisingly, it also disappeared at the corresponding time in controls; it reappeared after 48 h in the seizure group and after 24 h in controls. Differences in the von Frey hairs test occurred at 5 and 60 min post-seizure, however, these differences could not be explained by limb anatomy; although, different thermal and mechanical nociception mechanisms could be significant. The unexpected reactions in controls could be related to brief social and physical interactions between the two groups. and J. Mareš, R. Rokyta.
Ischemia can contribute to the inner ear pathology and hearing loss. To determine the susceptibility of inner and outer hair cells (IHCs/OHCs) to ischemic and post-ischemic period, we used organotypic cultures of the organ of Corti isolated from P3 rats as an in vitro model of inner ear ischemia (oxygen-glucose deprivation, OGD). We identified the hair cells (HCs) by phalloidin staining. The cells with damaged cellular membrane integrity were identified by propidium iodide (PI)-exclusion assay. The cells with fragmented chromosomal DNA were detected by TUNEL assay. Organotypic cultures were subjected to a mild (3 h duration) or severe (4 h duration ) OGD, followed by a recovery period of 21 h and 20 h, respectively. Mild OGD induced a loss of 10-20 % HCs, whereas severe OGD induced loss of 35 % HCs. We confirmed that OHCs are less vulnerable to OGD than IHCs. Of all missing OHCs, 80-90 % was lost during the OGD period and 10-20 % during the recovery period. In contrast, the loss of IHCs was equal during both experimental periods. The OGD period was mainly associated with PI-positive nuclei. TUNEL-positive nuclei were a minor frac tion during the OGD period and increased during the recovery period, indicating the progression of DNA fragmentation. Our results implicate a differential susceptibility of IHCs and OHCs during and after ischemia-like insult, which may be of therapeutic consequence., N. Amarjargal ... [et al.]., and Obsahuje seznam literatury
Stellate ganglion blockade (SGB) with a local anesthetic increases muscle sympathetic nerve activity in the tibial nerve in humans. However, whether this sympathetic excitation in the tibial nerve is due to a sympathetic blockade in the neck itself, or due to infiltration of a local anesthetic to adjacent nerves including the vagus nerve remains unknown. To rule out one mechanism, we examined the effects of cervical sympathetic trunk transection on renal sympathetic nerve activity (RSNA) in anesthetized rats. Seven rats were anesthetized with intraperitoneal urethane. RSNA together with arterial blood pressure and heart rate were recorded for 15 min before and 30 min after left cervical sympathetic trunk transection. The baroreceptor unloading RSNA obtained by decreasing arterial blood pressure with administration of sodium nitroprusside was also measured. Left cervical sympathetic trunk transection did not have any significant effects on RSNA, baroreceptor unloading RSNA, arterial blood pressure, and heart rate. These data suggest that there was no compensatory increase in RSNA when cervical sympathetic trunk was transected and that the increase in sympathetic nerve activity in the tibial nerve during SGB in humans may result from infiltration of a local anesthetic to adjacent nerves rather than a sympathetic blockade in the neck itself., T. Ikeda ... [et al.]., and Obsahuje seznam literatury
Assessment of hepatic microcirculation by on-line visualization has been impossible for a long time. Sidestream dark-field (SDF) imaging is a relatively new method allowing direct visualization of both mucosal microcirculation and surface layers microcirculation of solid organs using hand-held probe for direct contact with target tissue. The aim of this study was to evaluate the feasibility of studying the rat hepatic microcirculation in situ by SDF imaging. The liver lobes were left in situ, and images were obtained using SDF imaging on the surface of the liver via upper midline laparotomy. Images were captured intermittently during 10-sec apnoea and recorded. The microvascular parameters were compared with previous validation studies. Clear high contrast SDF images were successfully obtained. Quantitative analysis revealed a mean FSD (functional sinusoidal density) of 402±15 cm/cm2, a sinusoidal diameter of 10.2±0.5 μm and postsinusoidal venular diameter of 33.9±13 μm. SDF imaging is a suitable noninvasive method for accurate quantification of the basic microcirculatory parameters of the liver in situ without a need to exteriorize the liver lobes. This method seems to be applicable in animal studies with possibility to use SDF imaging also intraoperatively, providing unique opportunity to study liver microcirculation during various experimental and clinical settings., V. Černý, Z. Turek, R. Pařízková., and Obsahuje seznam literatury
The development of neurogenic pulmonary edema (NPE) can be elicited by an immediate epidural balloon compression of the thoracic spinal cord. To evaluate whether a slower balloon inflation could prevent NPE development, we examined the extent of NPE in animals lesioned with a rapid (5 μl - 5 μl - 5 μl) or slow rate (3 μl - 2 μl - 2 μl - 2 μl - 2 μl - 2 μl - 2 μl) of balloon inflation. These groups were compared with the NPE model (immediate inflation to 15 μl) and with healthy controls. Slow balloon inflation prevented NPE development, whereas the pulmonary index and histology revealed a massive pulmonary edema in the group with a rapid rate of balloon inflation. Pulmonary edema was preceded by a considerable decrease in heart rate during the inflation procedure. Moreover, rapid inflation of balloon in spinal channel to either 5 μl or 10 μl did not cause NPE. Thus, a slow rate of balloon inflation in the thoracic epidural space prevents the development of neurogenic pulmonary edema, most likely due to the better adaptation of the organism to acute circulatory changes (rapid elevation of systemic blood pressure accompanied by profound heart rate reduction) during the longer balloon inflation period. It should be noted that spinal cord transection at the same level did not cause neurogenic pulmonary edema., J. Šedý ... [et al.]., and Obsahuje seznam literatury
This study aimed to investigate the vasoactivity of sulfur dioxide (SO2), a novel gas identified from vascular tissue, in rat thoracic aorta. The thoracic aorta was isolated, cut into rings, and mounted in organ-bath chambers. After equilibrium, the rings were gradually stretched to a resting tension. Isometric tension was recorded under the treatments with vasoconstrictors, SO2 derivatives, and various drugs as pharmacological interventions. In endothelium-intact aortic rings constricted by 1 μM phenylephrine (PE), SO2 derivatives (0.5 – 8 mM) caused a dose-dependent relaxation. Endothelium removal and a NOS inhibitor L-NAME reduced the relaxation to low doses of SO2 derivatives, but not that to relatively high doses (≥ 2 mM). In endothelium-denuded rings, SO2 derivatives attenuat ed vasoconstriction induced by high K+ (60 mM) or CaCl2 (0.01-10 mM). The relaxation to SO2 derivatives in PE-constricted rings without endothelium was significantly inhibited by blockers of ATP-sensitive K+ (KATP) and Ca2+-activated K+ (KCa) channels, but not by those of voltage-dependent K+ channels, Na+-K+-ATPase or Na+-Ca2+ exchanger. SO2 relaxed vessel tone via endothelium-dependent mechanisms associated with NOS activation, and via endothelium-independent mechanisms dependent on the inhibition of voltage-gated Ca2+ channels, and the opening of KATP and KCa channels., Y.-K- Wang., and Obsahuje seznam literatury
Numerous hypotheses have been proposed about the pathogenesis of the polycystic ovarian syndrome (PCOS). However, hormonal control of persistent follicles has not be enestablished. The objective of the present study was to compare the follicular structure and hormonal profiles of rats treated with the adrenocor ticotrophic hormone (ACTH) with two experimental models of PCOS. ACTH-treated animals were compared with those exposed to continuous light, those treated with estradiol valerate, and with control (in proestrous and diestrous). Serum hormone levels, histomorphometrical changes, and immunoexpression of vimentin, cytokeratins, cadherins, and proliferating cell nuclear antigen (PCNA) were examined. Treatment with ACTH resulted in an elevation of corticosterone secretion with LH reduction but without changes in ovarian morphology. Although stress (or ACTH) stimulation may be only one of pathophysiological mechanisms involved in follicular cystathogenesis in other species, we do not have important evidence to suppose that this would happen in rats., C. Bavaralle, N. R. Salvetti, G. A. Mira, J. A. Lorente, H. H. Ortega., and Obsahuje bibliografii a bibliografické odkazy