出版社：Japan Society of Circulation Control in Medicine
摘要：Severe cerebral acidosis has been reported to worsen cerebral ischemic injury. Recent works have suggested that apoptosis as well as necrosis can be observed following cerebral ischemia. Acidosis was reported to activate some kind of endonuclease, which may lead cells to apoptosis. Accordingly, cerebral acidosis may worsen cerebral ischemic injury by increasing apoptotic cell death. In this study, we evaluated whether the ratio of apoptotic cell death increased in proportion as the degree of acidosis progressed after hypoxic insult in neuronal cells. We utilized PC 12 cells, which are derived from rat phenochromocytoma. The cells were incubated in N-[2-hydroxyethyl] piperazine-N’-[2-ethanesulfonic acid]-buffered mediu, the pH of which was adjusted at 7.4, 6.8, 6.2, 5.6 or 5.0. Hypoxic insult was induced by filling the chamber with N2. Eight, 24, 48 or 72 hours after incubation, cells were stained with Hoechst 33342 and propidium iodide and analyzed under a nonconfocal fluorescence microscope to distinguish whether cells were apoptotic or necrotic. The percentage of apoptosis at pH 6.2 was 9.4±2.9 and 19.9±7.5 % at 8 and 24 hours, which was slightly but significantly higher compared to pH 7.4 (3.1±1.5 and 12.7±5.1 %, respectively). After that, apoptosis was not enhanced by any degrees of acidosis. Acidosis below pH 5.6 increased the percentage of necrosis to more than 80 % during the entire period. Contrary to our expectation, apoptosis was slightly enhanced by moderate acidosis only in the early phase of hypoxic insult, while severe acidosis increased necrotic cell death during the total period of hypoxic insult. Accordingly, we propose that the main cause of aggravation of hypoxic neuronal damage by acidosis is enhancement of necrosis, whereas apoptosis may play only a small role.
关键词：Acidosis ; Cell death ; apoptosis ; necrosis ; Cerebral ischemia ; hypoxia ; cell culture ; PC 12 cells
