Nuclear Magnetic Resonance Studies of Sodium Ions in Isolated Frog Muscle and Liver

Nuclear magnetic resonance (NMR) was used to determine Na + complexing in muscle and liver (at 23°C) from bullfrogs ( Rana catesbeiana) and to study the influence of temperature on Na + complexing in muscle from leopard frogs ( Rana pipiens). The Na + complexed in muscle and liver was found to be 36.6 ± 4.6% and 66.1 ± 3.5% respectively. A temperature decrease from +34°C to -2°C results in a 20% decrease in the mobility of the free Na + in the fresh muscle. This 20% decrease in mobility results in about 50% of the free Na + at 34°C being complexed at the lower temperature.