Biomaterial Database

Diurnal rhythms in cardiorespiratory function of the fetal baboon. 1996

K L Fletcher, and K Leung, and M M Myers, and R I Stark

Department of Pediatrics, Columbia College of Physicians and Surgeons, New York 10032, USA.

Diurnal periodicities of cardiorespiratory function were monitored between 144 and 156 days of gestation (term = 175 days) in six chronically instrumented fetal baboons. For each fetus, 5-11 days of electrocardiographic and tracheal fluid pressure data were summarized as hourly means of fetal heart rate (FHR), standard deviation of FHR, breath-to-breath interval (B-Bi) and percent time spent in fetal breathing activity (PFB). Summaries were evaluated by cosinor analysis to determine the least squares fit to a 24-h cycle. For all fetuses, FHR had a significant (P < 0.001) diurnal rhythm with peak to nadir fluctuations of 17.4 beats/min around a 24-h mean of 163.2 beats/min. The time of the peak FHR was similar across animals occurring in the mid-day between 10:49 h and 14:45 h. For each fetus, standard deviation of FHR also had a significant (P < 0.01) diurnal periodicity with highest values at night between 20:15 h and 02:04 h. The times of the acrophase for these heart rate parameters were correlated (R = 0.88, P < 0.02) across fetuses. Significant (P < 0.001) 24-h rhythms were found in four of six fetuses for B-Bi and five of six for PFB. These PFB rhythms accounted for a fluctuation of 14.4% around a mean of 36.9 +/- 4.5%. In contrast to heart rate, the acrophases of fetal breathing parameters were distributed throughout the entire 24-h cycle and not significantly correlated across fetuses. It is concluded that diurnal rhythms of fetal heart rate, which are synchronized with light/dark conditions in the environment, are evidence for a passive response or entrainment of fetal systems to maternal circadian influences. Alternately, the absence of synchronization across fetuses in daily rhythms of fetal breathing activity provides evidence for a functioning fetal pacemaker, and not simply the imposition of maternal rhythms on her fetus. This differential in the cardiac and breathing activity of the developing primate indicates that pathways for entrainment of fetal pacemaker function are subject to important maturational influences during late gestation.

UI	MeSH Term	Description	Entries
D010215	Papio	A genus of the subfamily CERCOPITHECINAE, family CERCOPITHECIDAE, consisting of five named species: PAPIO URSINUS (chacma baboon), PAPIO CYNOCEPHALUS (yellow baboon), PAPIO PAPIO (western baboon), PAPIO ANUBIS (or olive baboon), and PAPIO HAMADRYAS (hamadryas baboon). Members of the Papio genus inhabit open woodland, savannahs, grassland, and rocky hill country. Some authors consider MANDRILLUS a subgenus of Papio.	Baboons,Baboons, Savanna,Savanna Baboons,Baboon,Baboon, Savanna,Papios,Savanna Baboon
D010507	Periodicity	The tendency of a phenomenon to recur at regular intervals; in biological systems, the recurrence of certain activities (including hormonal, cellular, neural) may be annual, seasonal, monthly, daily, or more frequently (ultradian).	Cyclicity,Rhythmicity,Biological Rhythms,Bioperiodicity,Biorhythms,Biological Rhythm,Bioperiodicities,Biorhythm,Cyclicities,Periodicities,Rhythm, Biological,Rhythmicities,Rhythms, Biological
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D011270	Pregnancy, Animal	The process of bearing developing young (EMBRYOS or FETUSES) in utero in non-human mammals, beginning from FERTILIZATION to BIRTH.	Animal Pregnancies,Animal Pregnancy,Pregnancies, Animal
D012119	Respiration	The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (	Breathing
D002940	Circadian Rhythm	The regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs or environmental and physiological stimuli.	Diurnal Rhythm,Nyctohemeral Rhythm,Twenty-Four Hour Rhythm,Nycthemeral Rhythm,Circadian Rhythms,Diurnal Rhythms,Nycthemeral Rhythms,Nyctohemeral Rhythms,Rhythm, Circadian,Rhythm, Diurnal,Rhythm, Nycthemeral,Rhythm, Nyctohemeral,Rhythm, Twenty-Four Hour,Rhythms, Circadian,Rhythms, Diurnal,Rhythms, Nycthemeral,Rhythms, Nyctohemeral,Rhythms, Twenty-Four Hour,Twenty Four Hour Rhythm,Twenty-Four Hour Rhythms
D005260	Female		Females
D005333	Fetus	The unborn young of a viviparous mammal, in the postembryonic period, after the major structures have been outlined. In humans, the unborn young from the end of the eighth week after CONCEPTION until BIRTH, as distinguished from the earlier EMBRYO, MAMMALIAN.	Fetal Structures,Fetal Tissue,Fetuses,Mummified Fetus,Retained Fetus,Fetal Structure,Fetal Tissues,Fetus, Mummified,Fetus, Retained,Structure, Fetal,Structures, Fetal,Tissue, Fetal,Tissues, Fetal
D006339	Heart Rate	The number of times the HEART VENTRICLES contract per unit of time, usually per minute.	Cardiac Rate,Chronotropism, Cardiac,Heart Rate Control,Heartbeat,Pulse Rate,Cardiac Chronotropy,Cardiac Chronotropism,Cardiac Rates,Chronotropy, Cardiac,Control, Heart Rate,Heart Rates,Heartbeats,Pulse Rates,Rate Control, Heart,Rate, Cardiac,Rate, Heart,Rate, Pulse
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia