LYMPHOCYTE TRAFFICKING FOLLOWING ACUTE STRESS AND ALTITUDE HYPOXIA IN LOW AND HIGH HEMATOCRIT SHEEP

Abstract

The object of the present study was to investigate small and large lymphocytestrafficking in sheep with low and high hematocrit values following shearing,exposure to moderate altitude and transport to low altitude. Twenty out of 101 Ilede France ewes (1-7 years old) were used in the present experiment. All ewes ofthe flock were artificially inseminated in May 2015 following estrussynchronization. The animals were allocated into two groups following threefoldmeasurements of hematocrit in all ewes as follows: I- low hematocrit group (n=10)and II - high hematocrit group (n=10). The ewes were transported to the PetrohanPass (1440 m above sea level) in June 2015 immediately after shearing, conductedat the experimental farm of the Institute of Animal Science, Kostinbrod (500 mabove sea level). Blood samples were collected before shearing, immediately aftershearing, 3 h after shearing, at 14 d following exposure to moderate altitude,immediately after transport to low altitude and following 7d of stay at low altitude.All leukocyte subpopulations were counted microscopically. In the current studywe presented the percentage of lymphocytes only, including small and large(reactive) lymphocytes. High and low hematocrit ewes had different percentage ofsmall lymphocytes when exposed to various acute and chronic stress stimuli. Therewere significant differences in the percentage of large (reactive) lymphocytesbetween low and high hematocrit ewes following blood collection and immediatelyafter shearing. The observed difference in small lymphocyte dynamics among thegroups in response to different stress stimuli was attributed to hematocrit relateddifferences in the time course and magnitude of lymphocyte distribution at earlyand late phases of stress. The results were interpreted to mean that the differencesin lymphocyte trafficking between the two groups of sheep in response to stresswere related to possible difference in the share of aerobic and glycolytic pathwaysfor energy supply.