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Objective To study the influence of high calcium ion environment on the membrane current of denervated aortic smooth muscles in iso-osmotic condition,as well as study the myogenic spontaneous vasomotion of the aortic smooth muscles under different pre-load state and intervention of calcium-channel blockers.Methods Smooth muscle samples were taken from the aortic smooth muscle layer of Kunming mice.The samples were fixed at two-ends in relaxed state and infiltrated in Ringer's solution.After stabilization,a glass microelectrode was adsorbed on the smooth muscle membrane to form gigaohm-seal.The current state of the membrane was observed under the physiological osmotic pressure.Then,the calcium ions concentration in the Ringer's solution was increased from 0.9 mol/L to 1.2 mol/L,and the immediate change of membrane current was observed after changing of osmotic pressure.Finally,the membrane potential change in iso-osmotic condition was observed when the pre-load was increased to 1 g,and the spontaneous vasomotion curves of the samples were recorded.Results In the relaxation state,the membrane current of the smooth muscle was increased significantly,i.e.(10.25±1.34) pA vs.(24.91±3.27) pA (P＜0.05),when the calcium ion concentration was increased from 0.9 mol/L to 1.2 mol/L in iso-osmotic condition.When the pre-load was increased,the variation amplitude of the membrane current was increased in iso-osmotic condition,i.e.(10.25±1.34) pA to (15.33±4.33) pA (P＜0.05) for the lower calcium ion concentration,and (24.91±3.27) pA to (33.31±7.25) pA (P＜0.05) for the higher calcium ion concentration.If only increasing the pre-load,the myogenic spontaneous vasomotion could be increased by 175％ for the condition of lower calcium ion concentration (0.9 mol/L).When the calcium ion concentration was increased to 1.2 mol/L,the spontaneous vasomotion frequency of the specimen was increased,and the range of the vasomotion could be further increased by 40％.After pretreatment with the calcium-channel blocker (0.5 g/L nitrendipine),the membrane current and myogenic spontaneous vasomotion were significantly decreased in the higher calcium ion environment,which indicated that the membrane potential and spontaneous vasomotion was dominated by calcium ions.Conclusions The increase of extracellular calcium ion concentration not only can improve the excitability of the aorta smooth muscle cells,but also can cause significant spontaneous vasomotion,and can improve the compliance of the smooth muscle tissue in pre-load variation.The calcium-channel blockers can inhibit calcium-dominated transmembrane currents,reduce myogenic spontaneous vasomotion,and enhance the stiffness of smooth muscle,which may have negative effects on windkessel vessel function.
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Objective To investigate the role and influence of physiological loading and overloading on microgravity-induced osteoporosis, so as to find a reliable way to prevent or treat related-orthopedic disorders in astronauts induced by long-time space activity. Methods The microgravity environment in space was simulated by tail-suspension experiment, then the osteoporosis models of mice were built. A total of 32 C57BL/6J mice were randomly and evenly separated into four groups: normal group (normal), tail-suspension group (TS), physiological loading group (loading) and overloading group (overloading). Periodic dynamic mechanical load was applied on the left tibia in loading group and overloading group during tail-suspension test. After four weeks, tibial mechanical properties, micro-parameters of bone trabecular, biochemical indices and osteogenesis-related gene expression in each group were compared and analyzed. Results A great loss of tibial cancellous bone, significantly lower tibial biomechanical expression, serious damage of microstructure and weaker osteogenic activity were found in tail-suspended mice as compared with those of normal group. Physiological loading could clearly improve mechanical properties of bones, microstructure of bone trabecular, osteogenic activity and relative gene expression (P＜0.05). Overloading could also improve the condition of microgravity-induced osteoporosis, but the effect was not obvious (P＞0.05). Conclusions Tail-suspension can successfully simulate microgravity environment and duplicate osteoporosis model. Physiological loading can effectively prevent the emergence and development of microgravity-induced osteoporosis, while overloading can also counter microgravity-induced osteoporosis, but the results have no significant differences.
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The sensory system is developed and optimized by experiences given in the early phase of life in association with other regions of the nervous system. To date, many studies have revealed that deprivation of specific sensory experiences can modify the structure and function of the central nervous system; however, the effects of sensory overload remains unclear. Here we studied the effect of overloading the taste sense in the early period of life on the synaptic plasticity of rat hippocampus and somatosensory cortex. We prepared male and female Sprague Dawley rats with ad libitum access to a 0.1% saccharin solution for 2 hrs per day for three weeks after weaning on postnatal day 22. Saccharin consumption was slightly increased in males compared with females; however, saccharin intake did not affect chow intake or weight gain either in male or in female rats. We examined the effect of saccharin-intake on long term potentiation (LTP) formation in hippocampal Schaffer collateral pathway and somatosensory cortex layer IV - II/III pathways in the 6-week old saccharin-fed rats. There was no significant difference in LTP formation in the hippocampus between the control group and saccharin-treated group in both male and female rats. Also in the somatosensory cortex, we did not see a significant difference in LTP among the groups. Therefore, we conclude that saccharin-intake during 3~6 weeks may not affect the development of physiological function of the cortical and hippocampal synapses in rats.
Subject(s)
Adolescent , Animals , Female , Humans , Male , Rats , Hippocampus , Long-Term Potentiation , Nervous System , Plastics , Rats, Sprague-Dawley , Saccharin , Somatosensory Cortex , Synapses , Weaning , Weight GainABSTRACT
SN Ⅱ A on TGF betal/Smads signal pathway in local myocardium.
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Aim To determine the effects of sodium tashinoneⅡA sulfonate(TSN) on monophasic action potential(MAP) and tachycardia-induced electrical remodeling of rabbit atria in vivo.Methods Twenty-four rabbits were equally divided into two groups randomly: control group and TSN group.Electrical catheters were localized in the right atrium through right internal jugular vein.Right atrial MAP was recorded by multiple channel recording. ERP of right atrial(AERP) was assessed by programmed electrical stimulation before pacing and from 0～8 hours after the onset of the pacing.Results The AERP_(200 ms) of control group was shortened from (105.9?3.8) ms to(114.7?7.2) ms and the rate-dependent of control group's atrium was lost through the pacing process compared with TSN group before pacing(P
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Objective: To investigate the protective effect and mechanism of total peaony glycoside (TPG) on calium overloading injury of nerve cells in rat models. Methods: The nerve cells of cerebral cortex of primary rats were subject to tissue culture,and the calcuim-overloading injury models were induced by caffeine,KCl and NMDA respectively. Results:TPG possessed obvious protective effects on the nerve cells in rat models, increased the number of survival nerve cells and reduced the content of LDH released nerve cells.Conclusion: TPG can protect rat nerve cells with calium-overloading injuriy.
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Pulmonary edema may be defined broadly as excessive fluid accumulation in the interstitial and air spaces of the lung. We recently a previously healthy parturient with ritodrine treatment who suddenly developed severe pulmonary edema during a Cesarian Section under Genera) Anesthesia, For this presented cases, we believe that overloading, Ritodrine, oxytocin, ergot derivatives wi11 be the causative factors. We had good result with PEEP, diuretics, and morphines.
Subject(s)
Anesthesia , Diuretics , Lung , Morphine Derivatives , Oxytocin , Pulmonary Edema , RitodrineABSTRACT
Pulmonary edema may be defined broadly as excessive fluid accumulation in the interstitial and air spaces of the lung. We recently a previously healthy parturient with ritodrine treatment who suddenly developed severe pulmonary edema during a Cesarian Section under Genera) Anesthesia, For this presented cases, we believe that overloading, Ritodrine, oxytocin, ergot derivatives wi11 be the causative factors. We had good result with PEEP, diuretics, and morphines.