HOMEOSTATIC CONTROL OF RESPIRATORY METABOLISM IN BEETLES

Respiratory functions of diapausing adults of Bruchus affinis have been analysed by means of a recently invented ultra-microrespirographic scanning method. The method enables prolonged monitoring of respiratory patterns with sensitivity in nl of oxygen consumption or carbon dioxide release . min-1. The diapausing adults of B. affinis show special cycles in carbon dioxide production, which are called the Prague cycles. The principal features of these cycles can be summarized as follows: (a) the periodically repeated, sudden displacement of carbon dioxide from tissue buffers, with a velocity surpassing the rate of oxygen consumption up to 30-times; (b) a rather brief duration of emissions (usually less than 10 s), averaging only about 3% of the whole interburst period (3-5 min); (c) a virtual absence of carbon dioxide production between the cycles; (d) mechanical discharge of carbon dioxide out of the body by means of coordinated pulsations in haemocoelic pressure and (e) programmed nervous control of the cycles from autonomic nervous centres located in the meso- or metathoracic region. These results may represent the first experimental evidence for the programmed, nervous control of respiratory metabolism in an invertebrate animal.