Regulation of the efficacy of adrenergic synaptic transmission by autoadrenoreceptors in rat brain slices

A hypothesis of the role of autoadrenoreceptors in the processes of synaptic depression, facilitation, PSP amplitude stabilization and amplitude increase with the stimulation frequency growth is described by means of a mathematical model. Synaptic depression is realized by activation of alpha-autoadrenoreceptors, synaptic facilitation--by beta-autoadrenoreceptors activation. A "stable secretion zone" is formed between the autoadrenoreceptor activation curves at which noradrenaline secretion is stabilized. Experimental studies of H3-NA secretion from rats cerebral cortex slices showed that autoadrenoreceptors really form a stable secretion zone. The presence of stable secretion zone provides for self-facilitation and stabilization of H3-NA secretion elicited by 5-fold consecutive K+-depolarizations of slices with time interval 30 min. The absence of the stable secretion zone leads to destabilization of H3-NA secretion. With an increase of the stimulation intensity the curves of autoadrenoreceptors activity and stable secretion zone shift toward high noradrenaline concentrations.     

预防非妊娠期妇女复发性膀胱炎的临床证据

现有预防非妊娠期妇女膀胱炎复发的临床证据如下①连续预防性使用抗生素一系列随机对照试验研究表明,连续预防性使用抗生素(甲氧苄氨嘧啶、复方磺胺甲噁唑、呋喃妥英、头孢克洛或一种喹啉)6~12个月可以减少复发性膀胱炎的发生率,但各种不同用药方案间未发现感染率有差异。一个比较持续性每日使用抗生素与性交后使用抗生素的随机对照试验表明,1年后尿培养阳性率差异无统计学意义。②性交后预防性使用抗生素(复方磺胺甲噁唑、呋喃妥英或一种喹啉)4个随机对照试验研究表明,性交后2h内使用复方磺胺甲噁唑、呋喃妥英或喹啉较安慰剂能显著降低膀胱炎发生率。一个关于性交后预防性使用抗生素和每日连续使用抗生素的随机对照试验发现,1年后二者的膀胱炎发生率的差异无统计学意义。③一次性使用复方磺胺甲噁唑一个小样本随机对照试验发现,连续每日预防性使用复方磺胺甲噁唑与在膀胱炎症状出现后一次性使用复方磺胺甲噁唑相比,前者能显著降低膀胱炎发生率。但由于证据太有限,不能得出肯定结论。④酸果蔓汁(cranberry juice)和酸果蔓制品一个系统评价发现,酸果蔓汁及其制品能预防复发性膀胱炎的证据不足。⑤用马尿酸乌洛托品预防缺乏研究马尿酸乌洛托品的可靠的随机对照试验。