RESUMO
Thrombocytes are multifunctional, nucleated blood cells. Morphological changes in thrombocytes have been used as a physiological indicator of a stress response. This study investigated the effects of in vitro heat stress (HS) on the neutral red uptake activity of chicken thrombocytes. Chicken thrombocytes (98% pure) were prepared from adult Barred Plymouth Rock and Rhode Island Red males. The isolated thrombocytes were preincubated at normal (41 C) or HS (45 C) temperatures for 30 min before either a 30- or 90-min incubation with neutral red at these same temperatures. After incubation the cells were washed, lysed, and the internal neutral red concentrations analyzed. There was no difference in thrombocyte numbers or their uptake of neutral red in samples from males of these two chicken breeds. At 41 C thrombocytes actively took up neutral red over the 90-min incubation period. However, at 45 C thrombocyte internalization of neutral red was significantly reduced. At both time periods (30 and 90 min), thrombocytes at 41 C took up significantly (P < or = 0.05) more neutral red than their counterparts at 45 C. This lack of neutral red uptake was not due to cell death as monitored by Trypan blue exclusion. Following the 30-min incubation there was no difference in viability between thrombocytes at the two temperatures. Although there was a significant (P < or = 0.05) increase in cell death at 90 min for thrombocytes kept at 45 C, the livability difference was of a much smaller magnitude than the difference in neutral red uptake when comparing to cells cultured at 41 C. Neutral red uptake is a rapid, inexpensive and repeatable technique for the study of thrombocyte function.
