Aerobic metabolism in the bovine lens

The concentration of sodium in the lens is a sensitive index of its metabolic integrity. A bovine lens incubated in air for 22 hr at 34·5°C in a medium consisting only of inorganic salts has a sodium concentration only a little higher than normal. The inference that endogenous substrates are oxidized under these conditions was strengthened by the finding that there is a great increase in the sodium concentration if the metabolic inhibitors cyanide, amytal and 4-pentenoate are added to the medium, or if the air is replaced by nitrogen. However, if glucose is present in the medium, the inhibitors have no effect. Glutamate has been shown to be one such endogenous substrate; it appears to be oxidized at the same rate in the presence or absence of glucose. We were unable to detect oxidation of fatty acids, but our methods may have been too insensitive.