Research On The Mechanism Between Mitochondrial And Anoxic Toleration Of Hippocampal Neuron Enhanced By Hypoxia Preconditioning In Rats

Hypoxic preconditioning (HPC) is so called that pretreatment with non fatal lower concentration oxygen to some targets such as: cell, organ or tissue, in order to make these targets to be obtained tolerance to anoxia. Phenomenon of HPC about neural system was firstly found in hippocampal slices in 1986 by Schurr A. et al. The mechanism of HPC on neuron has been studied for twenty years, and found many elements to be involved. ATP sensitive potassium channels (Katp) is considered as a significant target of them since it was firstly found in cadiocyte membrane by noma et al. in 1983, and some research papers reported Katp play a key role in HPC on brain or cardia, but no report about mitochondrial Katp, until Inoue et al. firstly found it on inner membrane of mitochondrion in1991.Garlid at el. reported the protection from hypoxic preconditioning in heart has nothing to do with K_atp on cell membrane, indicated the above protection mostly through mitochondrial K_atp. Rajapakse at el. firstly reported mitochondrial K_ATP involved the protection of ischemic preconditioning in brain of neonatal rats in 2002. Tai kk et al. reported the opener of mito-Katp can resist the cytotoxiciy of rotenone to PC12.Up to now, no any paper reported the mechanism between mito- Katp to HPC on brain. As a one of most sensitive parts to ischemia/anoxia, hippocampus is often a classic model to be studied for neural system on anoxia or ischemia. The mechanism of HPC involved in mitochondrial Katp or cell membrane K_ATp is not well understood, to pursue this goal:1. We prepared models of HPC from whole body (hippocampal slices) to hippocampal neuron (cells cultured), and to study the toleration of hippocampal neurons to anoxia through as follows indexes:?Preparing hippocampal slices after finishing HPC in vivo, recording hippocampalneurons through whole recording by patch clamp technique, observing hyperpolarized potential, membrane potential and duration of survival during anoxia.?Estimating the survival rate of hippocampal neurons (cultured) after acute anoxia.?Fluorescent intension of intra-cellular calcium? Fluorescent intension of Rhodamine 123 The researched results as follows:a. The survival time of hippocampal neurons in slices of HPC is longer significantly than control group's during anoxia.b. The survival rate of hippocampal neurons in slices of HPC is higher significantly than control group's after anoxia.c. Fluorescent intension of intra-cellular calcium in HPC is lower significantly than control group's during anoxia.d. Fluorescent intension of Rhodamine 123 in HPC is more stable than control group's during anoxia.2. We used special closer of mito- KAtp (5-HD) and cell member KAtp (tolbutamide) respectively in HPC group, and to observe what difference after adding closer of mito-Katp, closer of cell member Katp or adding nothing. The researched results as follows:a. The survival time of hippocampal neurons adding 5-HD in slices in HPC is decreased significantly than adding nothing during anoxia.b. The survival rate of hippocampal neurons adding 5-HD (cultured) in HPC is decreased significantly than adding nothing after anoxia.c. Fluorescent intension of intra-cellular calcium adding 5HD in HPC is more stable than adding nothing during anoxia.d. Fluorescent intension of Rhodamine 123 adding 5-HD in HPC is more stable than adding nothing during anoxia.e. No significant changing of above indexes of hippocampal neurons adding tolbutamide than adding nothing during anoxia.