Light dependence of oxygen consumption by blowfly eyes recorded with a magnetic diver balance
- 111 Downloads
We measured the oxygen (O2) consumption of isolated blowfly eyes using a magnetic diver balance, a device for high-resolution volumetric O2 consumption measurements. The light-induced O2 consumption is at most three times the value of the dark consumption, which is 0.6 nl O2 s−1 eye−1, and is in good agreement with the estimates based on electrophysiological data. With longer stimuli the increase follows a double exponential time course. The respective time constants are approximately 2 and 20 s and show no dependence on light intensity, whereas the dependence of amplitudes can be fitted by a Hill equation. Decreasing the stimulus duration reveals that the peak in O2 consumption overshoots the time course induced by long stimuli. We suggest this may be a general feature of mitochondrial activation. The dependence of the O2 consumption peak on stimulus duration at high light intensity has a hump with stimulus durations of 10–20 ms, coinciding with the stimulus durations that start to induce the adaptation of the receptor potential.
KeywordsOxygen consumption Blowfly Photoreceptor Mitochondria Volumetric measurement
Transient receptor potential
Transient receptor potential-like
The experiments comply with the “Principles of Animal Care”, publication No. 86-23, revised 1985, of the National Institute of Health, and also with the Animal Protection Law of Republic of Slovenia (Zakon o zaščiti živali, Uradni list RS, št. 98-4617/1999, p. 14645). Work was supported by the Ministry of Education, Science and Sports of the Republic of Slovenia (grant J1-1593, research program P0-0524-0481). We wish to thank Dr. R. Paulsen (University Karlsruhe, Germany) for supplying us with fresh batches of blowflies several times.
- Brzin M, Oman S (1975) The magnetic diver differential microgasometer. Anal Biochem 70:526–536Google Scholar
- Hamdorf K, Kaschef AH (1964) Der Sauerstoffverbrauch des Facettenauges von Calliphora erythrocephala in Abhängigkeit von der Temperatur und dem Ionenmilieu. Z Vergl Physiol 48:251–265Google Scholar
- Hamdorf K, Hochstrate P, Höglund G, Burbach B, Wiegand U (1988) Light activation of the sodium pump in blowfly photoreceptors. J Comp Physiol A 162:285–300Google Scholar
- Hanke W, Hamdorf K, Horn E, Schlieper C (1977) Praktikum der Zoophysiologie, Sinnesphysiologie. Gustav Fischer Verlag, Stuttgart, 242 ppGoogle Scholar
- McCormack JG, Denton RM (1994) Signal transduction by intramitochondrial Ca2+ in mammalian energy metabolism. News Physiol Sci 9:71–76Google Scholar
- Mojet MH (1992) Phototransduction and light-induced mitochondrial activation in blowfly compound eyes. PhD Thesis, GroningenGoogle Scholar
- Stavenga DG, Tinbergen J (1983) Light dependence of oxidative metabolism in fly compound eyes studied in vivo by microspectrofluorometry. Naturwissenschaften 70:618–620Google Scholar
- Stušek P, Grosman M (1983) Simultaneous photometry and oxygen consumption measurements in insect eyes. Iugoslav Physiol Pharmacol Acta 19:413–426Google Scholar
- Tinbergen J, Stavenga DG (1987) Spectral sensitivity of light induced respiratory activity of photoreceptor mitochondria in the intact fly. J Comp Physiol A 160:195–203Google Scholar