Swimming capacity of mice after prolonged treatment with psychostimulants. III. Effect of fencamfamine on swimming endurance and availability of metabolic substrates.

The effect of long-term treatment with fencamfamine on swimming endurance and availability of metabolic substrates was investigated in mice. Fencamfamine (14 micrograms/g per day orally for 6 weeks) reduced maximum swimming capacity by more than 40%. This effect could not be attributed to motor incoordination or a diminution of pre-swimming levels of metabolic substrates such as liver and muscle glycogen or blood glucose and non-esterfied fatty acids. However, during swimming the hepatic and muscular glycogen stores were depleted more rapidly in the fencamfamine-treated animals. Thus it appears that fencamfamine leads more rapidly to a shortage of combustible substrates in the swimming animals.