抄録
As reported previously, a majority of heart rate variability (HRV) induced by human respiration showed remarkable postnatal development especially in low birth weight neonates. In this report, we compared the frequency components of HRV in mammalian neonates (human, pig and rat) and hatched white chicken. The power spectrum was obtained by autocorrelation-FFT method from the heart rate and respiration waves. A comparison of the cardiopulmonary reflex in human and pig neonates resulted in a similar developmental progression. In case of normal human neonate, respiration induced HRV was significant within a week after the birth, however it took approximately one month in low birth weight neonate (mean gestational age 33±1 weeks). In case of pig neonates, the HRV was significant a few days after birth and developed in parallel to the body weight. Rat neonates however showed negligible HRV until days 8 and it became significant at postnatal 1 month. The white chicken indicated similar HRV development as rat, and became significant after 38days-old (17days post hatching). The results indicated that the development of the respiration linked HRV was triggered by the birth in mammalian neonates and quickly grew subsequently. The results also suggested that the developmental maturity of HRV is strongly depend on the gestational period when comparing rat and the low birth weight human neonates. The trigger for the HRV formation was however unclear. We consider the gravity exposure may play an essential role of the post natal development of the cardiopulmonary reflex. [Jpn J Physiol 55 Suppl:S99 (2005)]
