The Development of Cardiac Rate Regulation in Preweanling Rats

Hofer, Myron A.; Reiser, Morton F.

doi:10.1097/00006842-196909000-00003

Cited by 101 publications

(71 citation statements)

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“…For instance, the heart rate of young rats (P3-P5) does not respond to handling stress, while older rats (P6-P16) show a decreased heart rate in response to handling stress (Hofer and Reiser, 1969). The heart rate response reaches an adult state only after P20, when handling elicits an increase in heart rate (Hofer and Reiser, 1969).…”

Section: Neonatal Development Of Other Autonomic Control Systemsmentioning

confidence: 99%

Neonatal maturation of the hypercapnic ventilatory response and central neural CO2 chemosensitivity

Putnam

Conrad

Gdovin

et al. 2005

Respiratory Physiology & Neurobiology

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The ventilatory response to CO 2 changes as a function of neonatal development. In rats, a ventilatory response to CO 2 is present in the first 5 days of life, but this ventilatory response to CO 2 wanes and reaches its lowest point around postnatal day 8. Subsequently, the ventilatory response to CO 2 rises towards adult levels. Similar patterns in the ventilatory response to CO 2 are seen in some other species, although some animals do not exhibit all of these phases. Different developmental patterns of the ventilatory response to CO 2 may be related to the state of development of the animal at birth. The triphasic pattern of responsiveness (early decline, a nadir, and subsequent achievement of adult levels of responsiveness) may arise from the development of several processes, including central neural mechanisms, gas exchange, the neuromuscular junction, respiratory muscles and respiratory mechanics. We only discuss central neural mechanisms here, including altered CO 2 sensitivity of neurons among the various sites of central CO 2 chemosensitivity, changes in astrocytic function during development, the maturation of electrical and chemical synaptic mechanisms (both inhibitory and excitatory mechanisms) or changes in the integration of chemosensory information originating from peripheral and multiple central CO 2 chemosensory sites. Among these central processes, the maturation of synaptic mechanisms seems most important and the relative maturation of synaptic processes may also determine how plastic the response to CO 2 is at any particular age.

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Section: Neonatal Development Of Other Autonomic Control Systemsmentioning

confidence: 99%

Neonatal maturation of the hypercapnic ventilatory response and central neural CO2 chemosensitivity

Putnam

Conrad

Gdovin

et al. 2005

Respiratory Physiology & Neurobiology

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“…Thus, during the first 2 weeks or so of life, spontaneous gross motor movements in rats were observed in the absence of corresponding changes in HR (Ashida, 1972;Hofer & Reiser, 1969), suggesting that the two systems may develop at different rates. A specific classically conditioned HR CR was established in 3-4-day-01d rats (L. T. Martin & Alberts, 1982), but the question of possible motor involvement was not evaluated.…”

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Classically conditioned heart rate and respiratory-motor activity in newborn and neonatal pygmy goats

Fitzgerald

Francisco

Metcalfe

et al. 1984

Animal Learning & Behavior

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Classical discrimination conditioning of heart rate (HR) and respiratory-motor (RM) activity was examined in 16 newborn (average age = 1 day) and 8 neonatal (average age = 2 weeks) pygmy goats over 4 days of conditioning involving an electric shock US and auditory CSs. On the 4th day, one-half of the animals in each group received a low to moderate dose of ethanol to test the resistance of the CRs to drug effects. Discriminated conditioning of RM activity but not HR occurred in the newborn group, indicating an absence of close coupling between skeletal-motor activity and HR at this early age. While the newborn group failed to show recognizable HR reactions to the CSs during the 4 days of testing, it did show a long-latency bradycardia UR beginning at 2 days of age that may have been secondary to baroreceptor reflex actions. The neonatal group displayed conditioning of both HR and RM activity.

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“…On the other hand, the developmental change in HR follows a different time course in small animals. In rats, HR increases from ϳ300 beats/min at birth to ϳ500 beats/min at ϳ1 mo of age (15,37). HR of anesthetized newborn mice (rats) also increases from ϳ360 (ϳ340) to ϳ440 (ϳ490) beats/min during the first postnatal week (17,26).…”

mentioning

confidence: 99%

“…This is because stressor stimuli due to the attachment of ECG electrodes produce a sympathetically and/or parasympathetically mediated response in HR. It has been shown that there is a series of stages by which HR responsiveness to stressor stimuli becomes established during the first few postnatal weeks (7,15,16,18,23,31). According to the pioneering work by Hofer and Reiser in 1969 (15), HR is unresponsive to stressor stimuli in the first few days but decreases between 6 and 16 days of age.…”

mentioning

confidence: 99%

“…According to the pioneering work by Hofer and Reiser in 1969 (15), HR is unresponsive to stressor stimuli in the first few days but decreases between 6 and 16 days of age. Finally at 20 days, the stressor stimuli are associated with an increase in HR (15), the adult pattern for most species. In this respect, noninvasive measurement of HR is a prerequisite for describing and comparing the basal HR during the first few postnatal weeks.…”

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confidence: 99%

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Quantitative evaluation of ontogenetic change in heart rate and its autonomic regulation in newborn mice with the use of a noninvasive piezoelectric sensor

Sato

2008

American Journal of Physiology-Heart and Circulatory Physiology

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Sato S. Quantitative evaluation of ontogenetic change in heart rate and its autonomic regulation in newborn mice with the use of a noninvasive piezoelectric sensor. Am J Physiol Heart Circ Physiol 294: H1708-H1715, 2008. First published February 8, 2008 doi:10.1152/ajpheart.01122.2007.-A reliable basal heart rate (HR) measurement in freely moving newborn mice was accomplished for the first time by using a novel noninvasive piezoelectric transducer (PZT) sensor. The basal HR was ϳ320 beats/min at postnatal day (P)0 and increased with age to ϳ690 beats/min at P14. Contribution of autonomic control to HR was then assessed. Sympathetic blockade with metoprolol significantly reduced basal HR at both P6 (Ϫ236 Ϯ 23 beats/min; mean Ϯ SE) and P12 (Ϫ105 Ϯ 8 beats/min), but atropine was without effect, indicating the predominant tonic adrenergic stimulation and absence of vagal control for basal HR in newborn mice. In contrast to stable basal HR during 5-min recording, HR measured by ECG (ECG-HR) was markedly decreased because of the restraint stress of attaching ECG electrodes, with accompanying freezing behavior. ECG-HR lowered and further decreased gradually during 5 min (slow cardiodeceleration) at P0 -P3 and rapidly decreased and gradually recovered within 5 min (transient bradycardia) at P9 -P14. The response was not uniform in P4 -P8 mice: they showed either of these two patterns or sustained bradycardia (9 -29%), and the number of mice that showed transient bradycardia increased with age (30 -100%) during the period. Studies with autonomic blockade suggest that the slow cardiodeceleration and transient bradycardia are mediated mainly by withdrawal of adrenergic stimulation and phasic vagal activation, respectively, and the autonomic control of HR response to restraint stress is likely to change from the withdrawal of adrenergic stimulation to the phasic vagal activation at different stages during P4 -P8 in individual mice. The PZT sensor may offer excellent opportunities to monitor basal HR of small animals noninvasively. slow cardiodeceleration; circulating catecholamine; phasic vagal activation; transient bradycardia; baroreflex THE MAMMALIAN HEART RATE (HR) changes dramatically from the fetal period to the early postnatal period. For example, the human HR is ϳ140 beats/min at birth and then decreases gradually during the course of development to ϳ70 beats/min in adults. Animals such as lambs (5,6,35) and pigs (12, 41) also show qualitatively similar ontogenetic changes in HR. On the other hand, the developmental change in HR follows a different time course in small animals. In rats, HR increases from ϳ300 beats/min at birth to ϳ500 beats/min at ϳ1 mo of age (15,37). HR of anesthetized newborn mice (rats) also increases from ϳ360 (ϳ340) to ϳ440 (ϳ490) beats/min during the first postnatal week (17,26).

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The Development of Cardiac Rate Regulation in Preweanling Rats

Cited by 101 publications

References 10 publications

Neonatal maturation of the hypercapnic ventilatory response and central neural CO2 chemosensitivity

Neonatal maturation of the hypercapnic ventilatory response and central neural CO2 chemosensitivity

Classically conditioned heart rate and respiratory-motor activity in newborn and neonatal pygmy goats

Quantitative evaluation of ontogenetic change in heart rate and its autonomic regulation in newborn mice with the use of a noninvasive piezoelectric sensor

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