Microcalorimetric Investigations on the Energy Metabolism of Lizards

The energy metabolism of three lizard species ( Podarcis milensis, Podarcis muralis and Lacerta agilis ) was investigated by means of microcalorimetry and polarography over the range of environmental temperatures between 17 and 35 °C encountered by active lizards during summer in Europe. In non-stimulated animals, the maximum and mean heat production rates were highest around 30°C for all species and amounted to 3.9±1.1 mWg −1 and 2.1±0.5 mWg −1 , respectively. Resting metabolism contributed approximately 60% to the mean routine heat dissipation; the remainder originated from locomotory activity, 43% of which was based on anaerobic energy metabolism. From simultaneous determinations of heat dissipation and oxygen consumption, an average oxycaloric equivalent of 18.6±3.2 J ml −1 O 2 was calculated, which rose to 26.6±7.1 J ml −1 O 2 during short bursts of locomotion. Note: Institut fur Physiologie, Ruhr-Universitat Bochum, Universitatsstrasse 150, D-4630 Bochum, Germany.