Hemorrhage affects the ability of murine peritoneal macrophages to alkanize intracellular pH in acidic environments.

Although departures from the normal physiologic pH range, associated with states of shock, injury, and/or infection are thought to impair phagocytic function and chemotaxis, it remains unknown if the ability of the peritoneal macrophage (pMø) to gate H+ is affected following hemorrhagic shock. To study this, male C3H/HeN mice were bled to a BP of 40 mm Hg and maintained at that level for 1 hr. Following resuscitation with the shed blood plus 2x that volume as Ringer's lactate, pMø was harvested via lavage in bicarbonate-free RPMI 1640 and enumerated to 2 million cells/ml. PMø was then loaded with a pH-sensitive dye, BCECF (2 micrograms/ml), for 20 min and washed with a buffered Na+ solution followed by phorbol myristate acetate stimulation (0.5 micrograms/ml). The capacity of the pMø to gate H+ at an external pH of 7.35 or 6.7 was assessed via fluorescence spectrophotometry. PMø from hemorrhaged animals had a decreased ability to alkalinize intracellular pH compared to that of control (P < 0.05), indicating a decreased ability of these Mø to maintain internal pH in an acidic environment following hemorrhage. In additional studies, oxidative burst capacity was determined by employing a commercially available fluorogenic substrate, (Fc Oxiburst), which fluoresces during intracellular oxidation. Fluorescence (U x 10(6)) was assessed with the ACAS 570 laser cytometer, after 0 and 200 sec following ingestion of substrate. The results demonstrate that pMø oxidative burst capacity was also decreased following hemorrhage and resuscitation.