Seasonal changes in cation transport in red blood cells of grey squirrel (Sciurus carolinensis) in relation to thermogenesis and cellular adaptation to cold - Willis, J.S.; Ming-ji, Z. (Elsevier)
1. Unidirectional influx of ^4^2K was measured in red cells of grey squirrels at seasonal intervals over two years.2. Na/K pump-related (i.e. ouabain-sensitive) K influx at 37^oC was maximal in cells collected in January and was more than three times greater than cells collected in summer. Na/K pump activity, maximized by loading the cells with Na, exhibited a similar difference.3. At 5^oC in fresh cells, ouabain-sensitive K influx, expressed as per cent of that at 37^oC, was highest in March. In Na-loaded cells it was lowest in summer.4. Passive ''leak'' K influx (i.e., the residual influx remaining in presence of ouabain and bumetanide) was highest in October, and declined progressively to the summer months, when it was only 27% of that in October.5. Cotransport (i.e., bumetanide-sensitive K influx) exhibited the same seasonal pattern as Na/K pump activity in fresh cells.6. Net gain of Na in cells stored at 5^oC for three days in March was less than half of that in January or summer.7. High transport activity in January may correlate with a requirement for increased non-shivering thermogenesis. However, red cells of grey squirrels exhibit maximum resistance to low temperature in March and at this time resemble the red cells of hibernating mammals.
http://dx.doi.org/10.1016/0300-9629(91)90528-K
Keywords: W; V