首页 | 本学科首页   官方微博 | 高级检索  
     


Intracellular pH during ischemia in skeletal muscle: relationship to membrane potential,extracellular pH,tissue lactic acid and ATP
Authors:Henrik Hagberg
Affiliation:(1) Department of Histology, University of Göteborg, P.O.B. 33031, S-40033 Göteborg, Sweden
Abstract:Intracellular pH (pHi) was measured with double-barrelled microelectrodes during 4 h of complete tourniquet ischemia in rabbit gastrocnemius muscle (group I). The pHi was related to extracellular pH (pHe), membrane potential (Em), tissue lactic acid (LA) and ATP. A fall in pHi from 7.00±0.03 to 6.60±0.05 occurred during 4 h of ischemia, with a slight pH-drop (0.07 pH units) during the initial hour and a more pronounced drop of 0.13 pH units during the last hour of ischemia. These changes were paralleled by a considerable decrease in pHe from 7.30±0.01 to 6.36±0.05 and a sixfold increase of tissue LA. The buffering capacity during the 4 h of ischemia was estimated to 81.9±5.6 mmol H+/l×pH. In parallel with the reduction in pHe, the resting membrane potential decreased from –90 mV and stabilised at around –60 mV after 2 h of ischemia. A less negative cell interior would favour H+ extrusion since the Em-EH+ gradient was unchanged at about –70 mV during the entire period of ischemia. This could contribute to muscle fiber buffering during ischemia.In another set of experiments (group II) the muscular glycogen reserve was reduced 20 min prior to a 4 h period of ischemia. Thereby an ischemic state was created where ATP levels decreased to 30% of initial, in contrast to the unaltered ATP content in group I. In the low-ATP group II the Em-EH+ gradient decreased to 58% of initial and the buffering capacity was slightly but significantly lower (64.6±4 mmol H+/l×pH) than in the high-ATP group I. Significant correlation coefficients were obtained between the ATP loss and the Em-EH+ gradient (r=0.861,P<0.001). These data suggest that maintenance of the transmembrane H+ gradient and to a certain degree the buffer capacity depend on the energy-state of the muscle cell.
Keywords:Intracellular pH  Extracellular pH  Membrane potential  Lactic acid  ATP  Ischemia
本文献已被 SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号