Impact of laparoscopic gases on peritoneal microenvironment and essential parameters of cell function.
Several experimental studies confirm the hypotheses that laparoscopic gases influence the development of tumor metastases [12, 14, 23]. The mechanism for this alteration of malignant tumor growth is still unknown. One reason might be an influence of the in sufflation gas on essential cell function regulating parameters. To investigate the changes of the intra- and extracellular milieu, four parameters--extra- and intracellular pH, intracellular free calcium levels, and tissue oxygen partial pressure--were measured during insufflation with carbon dioxide (CO2), helium (He), or a nonhypoxic gas mixture consistent of 80% CO2 and 20% O2.


METHODS
(In vitro experiments) Intracellular calcium and pH levels were measured in DHD/K12/TRb colon adenocarcinoma cells using fluorescence imaging microscopy. (In vivo experiments) Tissue oxygen partial pressure was measured using a flexible micro catheter (Licox CMP) implanted in the abdominal wall of rats. After establishing the pneumoperitoneum an optical system and an aspirator were inserted to control the position of the micro catheter and to aspirate wound exudates for pH measurements of the wound fluid.


RESULTS
Creating of pneumoperitoneum with both CO2 and helium caused a decrease in partial pressure of oxygen in the abdominal wall to about 5 mm Hg whereas insufflation with a nonhypoxic gas mixture (80% CO2 and 20% O2) induced no significant changes. The intra- and extra cellular pH values dramatically decreased during CO2 insufflation (7.4 to 6.2) in vitro. Helium caused a pH increase up to 7.6. Free intracellular calcium was enhanced during CO2 insufflation, whereas helium insufflation did not cause any changes in [Ca2+]i. Nevertheless, a significant decrease of [Ca2+]i was observed during reoxygenation following helium-induced hypoxia.


CONCLUSIONS
Our study demonstrates that insufflation with either CO2 or He causes significant changes of intra- and extracellular parameters regulating essential cell functions such as oxidative phosphorylation to produce ATP, cell proliferation, or onset of apoptosis.
D000138:Acidosis / Q000209:etiology; D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism; D002245:Carbon Dioxide / Q000009:adverse effects*; D002277:Carcinoma / Q000556:secondary; D002455:Cell Division / Q000502:physiology; D002477:Cells / Q000378:metabolism*; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D006371:Helium / Q000009:adverse effects*; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000209:etiology; D007327:Insufflation / Q000009:adverse effects; D010535:Laparoscopy / Q000009:adverse effects*; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000209:etiology; D010085:Oxidative Phosphorylation; D010537:Peritoneum / Q000473:pathology*; D051381:Rats; D011919:Rats, Inbred Strains; D014407:Tumor Cells, Cultured
D002245:Carbon Dioxide; D006371:Helium; D000255:Adenosine Triphosphate; D002118:Calcium