Indicators of Hypoxia Tolerance as Determined by Cellular Elements of Rat Blood

Abstract

Although hypoxia tolerance is mainly determined genetically, it is important to study individual variability of animal organisms in order to identify the factors that underlie their tolerance to hypoxic exposure. We investigated blood cell counts and coagulograms in Wistar rats as predictors allowing the animal population to be split into hypoxia-tolerant and hypoxia-intolerant individuals. The validity of the specific predictors’ choice was proved by a coincidence between the population split in accordance with the detected individual parameters and the results of testing animals in a decompression chamber at a rarefaction corresponding to the “rise to an altitude” of 11500 m above sea level. Circulating blood cells were quantitatively assessed by eighteen indicators before and after hypoxic exposure. The differences between animals low-tolerant (LT), high-tolerant (HT), and medium-tolerant (MT) to hypoxia were determined by five indicators: white blood cell count (WBC), granulocyte count (Gran#), red blood cell count (RBC), reticulocyte count/percent (RTC), and mean corpuscular hemoglobin (MCH). The RBC, RTC, and MCH values in HT rats were significantly higher than in LT animals (by 1.4, 1.9, and 1.1 times, respectively). The WBC and Gran# values in HT rats were lower than in LT individuals. The hypoxia tolerance indices (HTI) were calculated using the original formula. It was established that in LT rats, the HTI ≤ 0.203, in HT rats ≥ 0.335, and in MT rats < 0.335 but > 0.203. After testing in a decompression chamber, the activated partial thromboplastin time (APTT), thrombin time (TT), and prothrombin time (PT) decreased, but the fibrinogen level increased. LT rats were characterized by the lowest APTT, TT, and PT values and the highest values of the fibrinogen level. Our results indicate that one of the most important mechanisms underlying a high hypoxia tolerance in rats consists in sustaining reciprocal relationships between the complex of RBC indicators, which tend to increase under hypoxia, and Gran# indicators, which tend to decrease after hypoxic exposure.

Haematological Alterations in Calves With Acute Respiratory Distress Syndrome Due to Aspiration Pneumonia: A Prospective Study

“…During infectious or non-infectious conditions causing hypoxia, erythroid cells continue performing their specifi c functions, changing their numbers, size, or O 2 content. Th us, under hypoxic conditions, WBC counts in small laboratory rodents, mainly neutrophils, are reported to be elevated (Kondashevskaya et al, 2021). As a result of the correlation analysis, which is one of the main topics of the present study, a moderate negative correlation was determined between PaO 2 and WBC count (Table 4).…”

“…Th ese fi ndings could be a consequence of the adaptation and compensatory processes refl ecting an existing pulmonary disease, hypoxaemia, and the stimulation of erythropoiesis (Hanzlicek et al, 2010;Fraser et al, 2014). In a study in rats, hypoxia was determined by fi ve indicators: WBC, granulocyte and RBC counts, reticulocyte count/percent, and MCH levels (Kondashevskaya et al, 2021). However, in the present study, RBC, haematocrit, MCHC and Hb levels of the diseased calves were not statistically diff erent from the healthy ones.…”

“…Since blood serves as the primary channel for transferring CO 2 in the opposite direction and O 2 from the lungs to tissues, studies aimed at identifying the eff ects and/or refl ections of hypoxia mostly on blood (Kondashevskaya et al, 2021). Th at is why the use of arterial blood samples has been suggested in evaluating lung ventilation/damage (Bleul et al, 2007).…”