The breathing frequency is a common parameter to assess the radiation response of the lungs of laboratory rodents. Rats of the strain WAG/Rij which were bred in Hamburg show different breathing patterns which consist of short regular and long irregular breaths. Depending on the breathing pattern, the breathing frequency of untreated animals varies by a factor of three. Although this phenomenon might be strain-specific, it seems noteworthy because it might influence the results obtained after irradiation significantly, especially if breathing frequency is automatically converted into a numerical value.
