- 作者: Shih-Hurng Loh, Wei-Hwa Chen, Cheng-Hsien Chiang, Chien-Sung Tsai, Guo-Chen Lee, Jong-Shiaw Jin, Tzu-Hurng Cheng, Jin-Jer Chen
- 作者服務機構: Departments of Pharmacology, Gynecology, Cardiovascular Surgery and Pathology, National Defense Medical Center, " Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, ROC
- 中文摘要: --
- 英文摘要: 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (anNHS inhibitor) or removal of extracellular Na inhibitedthe acid extrusion entirely. Therefore, in the presentstudy, we provided evidence that two acid extrudersinvolved in acid extrusion in human atrial myocytes, onewhich is HCO independent and one which is HCOdependent, are mostly likely NHE and NHS, respectively.When we checked the percentage of contribution ofthese two carriers to pH recovery following induced aci-dosis, we found that the activity of N HE increased steep-1y in the acid direction, while that of NHS did not change.Our present data indicate for the first time that two acidextruders, NHE and NHS, exist functionally and pHdependently in human atrial cardiomyocytes.Intracellular pH (pHi) exerts considerable influence oncardiac contractility and rhythm. Over the last few years,extensive progress has been made in understanding thesystem that controls pH in animal cardiomyocytes. Inaddition to the housekeeping Na -H exchanger(NHE),the Na -HCO symporter (NHS) has been demonstratedin animal cardiomyocytes as another acid extruder.However, whether the NHE and NHS functions existin human atrial cardiomyocytes remains unclear. Wetherefore investigated the mechanism of pH recoveryfrom intracellular acidosis (induced by NH CI prepulse)using intracellular 2',7'-bis(2-carboxethyl)-5(6)-carboxy-fluorescein fluorescence in human atrial myocardium. InHEPES (nominally HCO -free) Tyrode solution, pH re-covery from induced intracellular acidosis could beblocked completely by 30 M 3-methylsulfonyl-4-piper-idinobenzoyl, guanidine hydrochloride (HOE 694), a spe-cific NHE inhibitor, or by removing extracellular Na . In3% CO2-HCO Tyrode solution, HOE 694 only slowed thepH recovery, while addition of HOE 694 together with
- 中文關鍵字: --
- 英文關鍵字: Intracellular pH, BCECF fluorescence, Na+-H+ exchanger, Na+-HCO-3 symporter, Acid extruder, Human atrium