Concentrations of lactate and pyruvate and temperature effects on lactate dehydrogenase activity in the tissues of the big brown bat (Eptesicus fuscus) during arousal from hibernation.
1. The rectal temperatures, steady state concentrations of lactate and pyruvate, and the LDH isoenzyme composition in the heart, liver, and pectoral muscle of hibernating and arousing Eptesicus fuscus were measured. 2. Bat rectal temperature increased from 8.86 to 33.1 degrees C during arousal. 3. During arousal, steady state concentrations of pyruvate and lactate increased significantly in the tissues, however they remained generally below the level necessary to saturate LDH at the respective temperature. 4. The activities of the two LDH isoenzymes, M4, the predominant form in bat liver, and H4, the main form in bat heart and pectoral muscle, show substrate-dependent temperature effects described by the equation, mu = (E beta S + E alpha K t)/(K t + S). 5. Temperature effects (mu) on bat LDH activity increased during arousal but remained significantly lower than mu determined at saturating concentrations of substrate (E beta). 6. The parameters E beta-E alpha, E alpha and K tau are particularly important in describing the temperature dependence of LDH activity in tissues of the arousing bat.
D000818:Animals; D001143:Arousal; D001831:Body Temperature; D002685:Chiroptera / Q000502:physiology*; D006605:Hibernation; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D007773:Lactates / Q000032:analysis*; D019344:Lactic Acid; D008099:Liver / Q000032:analysis; D008433:Mathematics; D009132:Muscles / Q000032:analysis; D009206:Myocardium / Q000032:analysis; D011773:Pyruvates / Q000032:analysis*; D019289:Pyruvic Acid
D007527:Isoenzymes; D007773:Lactates; D011773:Pyruvates; D019344:Lactic Acid; D019289:Pyruvic Acid; D007770:L-Lactate Dehydrogenase