Circadian blood pressure pattern in full-term newborn infants.
ABSTRACT A fully automatic noninvasive device (Dinamap) was used for monitoring blood pressure (BP) and heart rate repetitively over 48 h in 21 full-term newborn infants (9 males and 12 females), aged 4 days in order to clarify the occurrence of a circadian rhythm (CR). The data collected were analyzed by computer statistical analysis. Mean values and standard error of BP and heart rate measured at hourly intervals in males and females were computed and plotted as chronograms. However, each newborn infant was analyzed for a CR of BP and heart rate by the single cosinor fit of a 24-hour cosine curve. The analysis of the chronograms revealed that the values of systolic and diastolic BP show an hour-by-hour significant fluctuation in male infants, but not in female infants. CR development of BP is present only in a minority of newborn infants and reveals sex and interindividual differences. CR of heart rate is absent in all infants. The physiological significance of these findings was discussed, and the importance of knowing the physiological variances of BP in infants in order to obtain a correct clinical evaluation was stressed.
- [Show abstract] [Hide abstract]
ABSTRACT: Recent studies have suggested that peripheral tissues in mammals have an autonomous circadian oscillator driven by negative feedback loops consisting of periodical expression of clock genes. In the present study we investigated the mechanism that regulates circadian rhythms in mammalian peripheral tissues, and observed developmental aspects in circadian expression of clock genes in the heart of postnatal rats. Daily expression patterns of clock genes (rPer1, rPer2 and BMAL1) and a clock-controlled gene Dbp were examined by Northern blot analysis. Circadian expression of rPer1, BMAL1 and Dbp mRNAs started between postnatal day 2 (P2) and P5, but rPer2 mRNA did not show rhythmicity until P14. Rhythmic expression of other genes in the heart occurred even in the absence of rhythmic rPer2 expression. These findings suggest that in the rat heart, rhythmic expression of rPer2 was not essential to generate circadian rhythmicity at the early postnatal stage. Judging from mRNA rhythms in the heart, it was probably after P20 that rats established the mature circadian system controlling peripheral rhythms.Neuroreport 08/2002; 13(10):1239-42. · 1.40 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Circadian rhythms of BP are established early in life. The ABPM coupled with an objective measure of activity is a powerful tool for the management of hypertension and is a sensitive tool for the dissection of the determinants of hypertension. The challenge for pediatricians in the future includes such important goals as establishing normal values for the circadian assessment of BP for a growing child, coupling of BP determinations with activity, using the ABPM to better understand BP tracking, studying the rhythms of families using the ABPM, educating the medical and lay communities of the importance of rhythmic phenomena, studying longitudinally patients with varying forms of hypertension, using the ABPM to test and optimize antihypertensive medications, and determining the proper diagnosis of hypertension in children based on end-organ damage rather than surrogate measures.Annals of the New York Academy of Sciences 09/1996; 783:227-41. · 4.38 Impact Factor