The Boundaries Of Reality: Where The Line Is To Be Held?

Abstract

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Red Blood Cell Metabolic Responses to Torpor and Arousal in the Hibernator Arctic Ground Squirrel

“…Torpor and arousal also impacted metabolism of amino acid beyond the aforementioned pathways, consistent with previous studies on plasma and liver in hibernators. 2,9,15,18,19 Of note, RBC levels of other aromatic amino acids (phenylalanine including tyrosine and tryptophan) were consumed during torpor and were normalized during arousal. Catabolism of tryptophan (an essential amino acid that during prolonged starvation may derive from proteolysis) was observed during torpor, with the levels of indoxyl, indole, kynurenine, picolinic acid and quinolic acid increasing in RBCs during torpor, prior to being normalized by arousal.…”

“…Over the past two decades, discovery-mode omics investigations employing transcriptomics, proteomics, and metabolomics approaches have been exploited to study molecular adaptations to hibernation in the liver, heart, kidney, skeletal muscle, intestine, brown adipose tissue, and plasma from different small mammalian hibernators. [2][3][4][5][6][7][8][9][10][11][12][13][14][15] In particular, extensive exploratory investigations have documented plasma metabolic adaptations in hibernating small mammals, 2,[16][17][18] including a comprehensive description of plasma metabolic phenotypes during entrance into and exit from torpor, as well as early/late and interbout arousal stages. 19 This body of literature has contribute to formulate the hypothesis that interbout arousals, which consume over 70% of winter energy in hibernators, 20 are necessary to replenish circulating levels of metabolic substrates (especially free fatty acids and amino acids) that are consumed by metabolism at low body temperature during torpor.…”

“…19 This body of literature has contribute to formulate the hypothesis that interbout arousals, which consume over 70% of winter energy in hibernators, 20 are necessary to replenish circulating levels of metabolic substrates (especially free fatty acids and amino acids) that are consumed by metabolism at low body temperature during torpor. 4,9,12 At the same time, arousal has been shown to promote the removal from the bloodstream of metabolic waste products that accumulate during torpor. 4,9,12 In arctic ground squirrels (Spermophilus parryii) oxygen consumption decreases by >90% during torpor (which results in decreased body temperature, heart and breathing rates), and increases profoundly during arousal to meet sudden metabolic demands for thermogenesis, mostly fueled by oxidation of fat stores accumulated during fall.…”

“…4,9,12 At the same time, arousal has been shown to promote the removal from the bloodstream of metabolic waste products that accumulate during torpor. 4,9,12 In arctic ground squirrels (Spermophilus parryii) oxygen consumption decreases by >90% during torpor (which results in decreased body temperature, heart and breathing rates), and increases profoundly during arousal to meet sudden metabolic demands for thermogenesis, mostly fueled by oxidation of fat stores accumulated during fall. RBCs-by far the most abundant host cell in the human body 21,22 -play a key role in oxygen transport and offloading.…”