Identifying a site for maximum delivery of oxygen to transplanted cells

For in vivo cell implantation techniques to be successful, the energy and m etabolic substrate requirement of the cells being grown must be met. Certai n cells with high-energy requirements (e.g., hepatocytes, pancreatic island cells) experience a high degree of cell death after implantation due to a limited supply of oxygen. We proposed that the pleural cavity might be an o xygen-rich environment and hence an excellent site for cell implantation. T o test the hypothesis that the delivery of oxygen to the pleural cavity is directly proportional to the inspired oxygen concentration we measured the pO(2) of saline instilled in the pleural cavity as compared to that of the peritoneal cavity. We postulated that the physiologic basis for any differe nce was the result of direct diffusion of oxygen into the pleural space acr oss the alveoli. The study was conducted on sheep (n = 6), after induction of general anesthesia, in two phases, control and experimental. Saline was instilled into the peritoneal and pleural cavities via catheters. after equ ilibration at given FiO(2), the pO(2) of the paline aspirated from the two cavities was compared. In the experimental group, animals were sacrificed ( no circulation) and ventilated. The same sequence of steps as in the contro l phase were repeated. In the control group, the pO(2) of saline aspirated from the pleural cavity approached the arterial pO(2) at all FiO(2) levels. The pO(2) of the peritoneal saline aspirate fell over time. In the experim ental phase (no circulation), the pO(2) of the pleural cavity saline rose t o >400 mmHg. We conclude that this is a result of direct diffusion and is a potential source of unlimited oxygen supply not dependent on vascular supp ly.