SUMMARY: Rates of oxygen uptake and heat dissipation were measured in cultures of that had been induced to divide synchronously by adding 2 mM-2#-deoxyadenosine and then removing the inhibitor after 4 h. Respiratory oscillations occurred during the last 1.5h of treatment with deoxyadenosine and throughout the subsequent period of synchronous growth. Before completion of the first synchronous division three peaks of oxygen uptake occurred, the third peak being coincident with cell division. These peaks were less sensitive to the rate-stimulating effect of the uncoupler, carbonyl cyanide -chlorophenylhydrazone, than were the troughs, so that in the presence of the uncoupler the oscillations were attenuated. In the absence of uncoupler, heat dissipation of the culture increased linearly during and after deoxyadenosine treatment, with sharp increases (approximate doublings) in the rate of dissipation occurring at intervals similar to the mean generation time of an exponential culture. Heat dissipation also increased continuously in samples removed from such a culture and incubated with the uncoupler. The possible modulation of oxygen uptake rates by respiratory control, and the implications of linear increases in heat dissipation are discussed.


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