Regulation of Heart Rate Variation by the Autonomic Nervous System in Neonatal Lambs
作者:
ANJA SIIMES,
ILKKA VÄLIMÄKI,
KARI ANTILA,
MERVI JULKUNEN,
TAINA METSALA,
LAURI HALKOLA,
H S SARAJAS,
期刊:
Pediatric Research
(OVID Available online 1990)
卷期:
Volume 27,
issue 4
页码: 383-391
ISSN:0031-3998
年代: 1990
出版商: OVID
数据来源: OVID
摘要:
We studied the role of the autonomic nervous system in the regulation of heart rate variation (HRV) in 12 chronically instrumented neonatal lambs. HRV was quantified from ECG tracings by computing periodic HRV distributions at frequencies of 0.02-1.00 Hz, using power spectral analysis of heart rate, and also by HRV indices. Heart rate declined more during the 1st than the 2nd mo after birth. Multiple regression analysis showed that the heart rate responses to vagal and to ß-adrenergic blockade had an independent negative association both with age and with the initial mean heart rate, whereas the overall HRV response had a positive association with age. Vagal blockade led to a 70-80% decrease in the beat-to-beat HRV in all lambs (p<0.001). The overall HRV indices decreased by 40-65% in lambs (< 30 d old (p<0.001) and about 30% in those >30 d old (p<0.05). In the power spectrum the greatest decrease was seen in the high-frequency components of HRV. β-Blockade led to a decrease of about 50% in all HRV (p<0.001) in the younger lambs, without frequency selection. In the older lambs, it had no effect on the beat-to-beat HRV, but the overall HRV (coefficient of variance) decreased maximally by 40% (p<0.01), with a significant reduction in the low-frequency components of HRV. These results suggest that in the regulation of HRV after birth dual control via the autonomic nervous system is most important. In the older lambs, developmental changes result in precise regulation of the fast heart rate fluctuations mainly by the vagal division, whereas the slow fluctuations are partially regulated by the vagal and β- adrenergic divisions.
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