“…Many investigations, which in the past required acute preparations, can be done in, surgically prepared conscious animals with minimal restraint. More recently radio-telemetry has been used to acquire information on physiological variables from unrestrained animals (Mellor and Pettinger, 1986). The advantages of the latter technique are that more efficient use can be made of resources, the animals are more re laxed and continuous monitoring for prolonged periods is possible.…”