Free Amino Acid Profile in Blood Plasma of Bats (Myotis dasycneme Boie, 1825) Exposed to Low Positive and Near-Zero Temperatures

Abstract

We analyze here for the first time the plasma free amino acid profile in pond bats (Myotis dasycneme Boie, 1825) living in the boreal Ural region and exposed experimentally to low positive and near-zero temperatures during their preparation for hibernation. Pond bats were caught in their mass habitation territory in the Middle Ural near the Smolinsky cave (N 56°28’, E 61°37’) in the third decade of September 2015. Qualitatively, blood plasma in pond bats contains 21 amino acids. In a model experiment carried out on pre-hibernating animals at a regular hibernation temperature (0–2°C), the total plasma pool of free amino acids increased significantly by 42% (irrespective of sex) and reached 1561.4 ± 112.6 μmol/L (p = 0.01). Under these experimental conditions, the fraction of glucogenic amino acids rose by 34% (p = 0.01) and that of essential ones by 80% (p = 0.001). Both in control and experimentally cooled pre-hibernating animals, the plasma was found to lack tryptophan, suggesting its utilization as a substrate in the synthesis of serotonin, a biogenic amine directly involved in the maintenance of hypothermia and hypometabolism in these chiropterans.