Influence of low environmental temperature on the phagocytic activity of bullfrog (Rana catesbeiana) thrombocytes

Abstract

The influence of low environmental temperature on phagocytic activity of bullfrog (Rana catesbeiana) thrombocytes induced by the injection of colloidal carbon in the dorsal lymphatic sac was investigated. Results showed that low environmental temperature decreased the thrombocyte phagocytic activity. Thrombocytes of animals treated and kept at 6°C showed a slow initial activity at 1h (16.3 ± 4.3; results expressed as mean ± SEM of positive thrombocytes in 400 cell analysed/animal; n=6), which increased slightly at 6h and 12h (45.8 ± 12.2; 55.5 ± 9.6), reaching a maximum reaction at 3d and 7d (80.3 ± 27.5; 78.3 ± 29.5). In contrast, bullfrogs maintained at 24°C presented an initial high reaction at 1h (90.0 ± 16.7), increasing markedly until 1d (196.0 ± 49.8), and then decreasing until 7d (56.0 ± 10.6). These data corroborate previous studies which demonstrated the effects of environmental temperature on multiple factors related to the host’s protective mechanisms.