On the Function of Haemoglobin in Chironomus After Oxygen Lack

ABSTRACT When Chironomus plumosus larvae receive aerated water after a period of anaerobiosis their oxygen consumption increases at once to a value well above the normal. This initial increase lasts for about 10 min. at 17° C., after which the oxygen consumption falls but continues to be slightly above normal for 1 hr. The initial sudden considerable rise in oxygen consumption is due to increased activity of the larvae ; it is absent in larvae made inactive by a low temperature of 1° C. Such larvae, however, maintain an oxygen consumption above the normal value for about 2 hr. The increased oxygen consumption lasting for 1-2 hr. after anaerobiosis represents the repayment of an oxygen debt, but this debt is only 0·5 % of the oxygen which would have been consumed had the anaerobic period been an aerobic one. The small size of the oxygen debt suggests that most of the products of anaerobic metabolism are excreted. The haemoglobin of the larvae does not function during the repayment in fully aerated water of the small oxygen debt. This is shown by experiments with and without carbon monoxide. During the initial short considerable rise in oxygen consumption at 17° C. due to larval activity after anaerobiosis the haemoglobin is functional. This activity occurs while the water is not yet fully aerated, and so the haemoglobin enables the larvae to maintain their activity aerobically in water containing little dissolved oxygen. In nature the undulatory activity of the larvae immediately after anaerobiosis must serve to ventilate the U-shaped tubes in which they live in the mud, and so to fill the tubes with aerated water.