Demonstration of action-potential-producing cells in the rat pineal gland in vitro and their regulation by norepinephrine and nitric oxide

PURPOSE: The purpose of this study was to analyse donor and time dependent variations in the frequencies of radiation-induced aberrations in chromosomes 1 and 2. MATERIALS AND METHODS: Human lymphocytes from two donors were irradiated with 1 and 2 Gy of X-rays. Chromosomal aberrations were scored in chromosomes 1 and 2 painted with different fluorochromes and in Giemsa stained cells. Two time displaced experiments were performed with lymphocytes of each donor. RESULTS: In cells of both donors chromosome 1 was generally more frequently involved in translocations than chromosome 2. This result was not always reproducible. Chromosome 2 showed a higher frequency of acentric fragments, especially following a dose of 1 Gy. Again interexperimental variations were observed. No differences between the two chromosomes were seen with regard to other aberration types. Both chromosomes showed less dicentrics and more acentric fragments than proportional to their DNA content. CONCLUSIONS: Chromosomes 1 and 2 show a different sensitivity to ionizing radiation. The difference is dependent on the aberration type and is not always reproducible. This variability could contribute to the difficulty in reaching a consensus regarding the radiosensitivity of individual chromosomes.