Evidence of Heritable Determinants of Decompression Sickness in Rats

INTRODUCTION: Decompression sickness (DCS) is a complex and poorly understood systemic disease caused by inadequate desaturation following a decrease of ambient pressure. Strong variability between individuals is observed for DCS occurrence. This raises questions concerning factors that may be involved in the inter-individual variability of DCS occurrence. This study aimed to experimentally assess the existence of heritable factors involved in DCS occurrence by selectively breeding individuals resistant to DCS from a population stock of wistar rats. METHODS: 52 males and 52 females Wistar rats were submitted to a simulated air dive known to reliably induce about 63% DCS: compression was performed at 100 kPa.min up to 1000 kPa absolute pressure before a 45 min long stay. Decompression was performed at 100 kPa.min with three decompression stops: 5 min at 200 kPa, 5 min at 160 kPa and 10 min at 130 kPa. Animals were observed for one hour to detect DCS symptoms. Individuals without DCS were selected and bred to create a new generation, subsequently subjected to the same hyperbaric protocol. This procedure was repeated up to the third generation of rats. RESULTS: As reported previously, this diving profile induced 67% of DCS, and 33% asymptomatic animals in the founding population. DCS/asymptomatic ratio was not initially different between sexes, although males were heavier than females. In three generations, the outcome of the dive significantly changed from 33% to 67% asymptomatic rats, for both sexes. Interestingly, survival in females increased sooner than in males. CONCLUSION: This study offers evidence suggesting the inheritance of DCS resistance. Future research will focus on genetic and physiological comparisons between the initial strain and the new resistant population.