Characteristics of Ion Transport in Kidney Cortex of Mammalian Hibernators

Recent studies have demonstrated resistance of membrane function to cold in several tissues of hibernating mammals. Thus, in hamsters or ground squirrels excitability of nerves (Chatfield et al., 1948; Kehl and Morrison, 1960) and cardiac muscle (see Marshall and Willis, 1962) is maintained at low temperatures, the resting membrane potential of atrial fibers is virtually unchanged by temperature between 31° and 5°C (Marshall and Willis, 1962), neuromuscular transmission of phrenic nerve diaphragm preparation persists to 5°C (South, 1961), and a relative resistance to cold swelling exists in skeletal muscle (Willis, 1962). A preliminary investigation has also re-