The effect of carbon monoxide on glucose metabolism and growth of rat embryos.

Rat embryos at days 11-12 of gestation cultured for 18 hours in vitro respond to reduced oxygen or to elevated levels of CO. Glucose consumption and lactate production increase while the growth rate decreases. The ratio of lactate produced to glucose consumed increases to values characteristic of earlier, more anaerobic, embryos. It is suggested that most of the energy consumed by the embryo goes to support growth and that the change in glucose metabolism results in a decrease in available energy which decreases the growth rate. The response to reduced oxygen levels is more marked than the response to elevated levels of carbon monoxide and we interpret the result to imply that oxygen transport in these embryos is primarily via solution rather than via combination with hemoglobin.