Aim. To elucidate whether an inhibited superoxide production（O 2 ） of neutrophils induced by commercial lactate based peritoneal dialysates（PDS） could be corrected after a transient intracellular acidosis. Methods. The intracellular pH（[pHi]） of human neutrophils incubatd in PDS was monitored with a spectrofluorometer with a pH sensitive dye （BCECF AM）. Neutrophilic O 2 stimulated by zymosan was determined in PDS with the superoxide dismutase inhibitable ferricytochrome c reduction

using a spectrophotometer. Results. The severe intracellular acidosis induced within 5 min by PDS at an extracellular pH of 5.2 could be promptly and completely recovered by a neutralization of the pH of media. However

O 2 by neutrophils exposed to the PDS for as little as 5 min was drastically and persistently inhibited

even the acidic [pHi] of cells had been fully returned for 1h. Conclusions. The intracellular acidification of cells in the initial phase could be transient and reversible

but impaired cell functions

at least in part including O 2 generating system

might be consistent and irreversible in the early stage of the cellular acidosis in the peritoneal cavity of CAPD patients. The findings above may be of particular importance in both clinic and cell biology.