缺氧对离体豚鼠乳头肌纵横向兴奋阈及有效不应期的影响

Effects of hypoxia on diastolic excitatory threshold nnd effec-tive refractory period along and across the electric field stlmu-latlun In Isolated papillary muscle of guinea pig

通过对离体豚鼠乳头肌行重复缺氧处理.观察心肌细胞在缺氧和复灌过程中舒张期兴奋阈(DET)和有效不应期(ERP)等参数的改变与电场刺激方向的关系.并探讨重复缺氧是否具有累积损伤作用.结果表明,缺氧开始后横纵向DET均有不同程度增加.第2次缺氧开始后DET均降至对照水平,至第2次复灌再次升高.ERP在缺氧过程中呈先延长后缩短的双向改变,ERP在第2次缺氧复灌过程中恢复减慢.结果提示,首次缺氧可减少随后缺氧过程中的DET升高,并具有电场梯度方向依赖性;重复缺氧对ERP的影响具轻度累积作用.

In the present study, the papillary musele of guinea pig was suhjcctcd to repealed hypoxia In investigate the relation ship between changes in parameters, including diastolic exci talory threshold ( DET ) and effective refractory period <FRP). and the direction of eleetirr field stimulation during hypoxij and rcpcrfusKin episode and lo explore whether re peated hypoxia would induee eumulaiivt injury lo myoeardi um. The results showed that DET of eithe,r direction in ereasfd after the onsrl uf hypnxia, and nturned lo the control level when the second hynxin episode Ixyaii. DET increased a gain during the-second reperfusion episodi. FRP prrsmied hiphasic changes, in which FRP was firsl kiigihencd and then shortened during thu hypoxia episode. FRF' returned lo the control level more slowly during the -eeond reperfu-ion episode than lhat during the first episode. The roulls indicnl ed that the first hypoxia atteiuiated ihe inenase of DFT in the suhseciuent hypoxia, which elcpendcd on the direcuon of elec irie field silnudaiion. and repealed hypoxin had :a shight accu mulative effect on FRP.