The time course of postnatal development of cardiovascular regulatory mechanisms is being studied in piglets Less than 1 day-3 months of age, from the viewpoint of efferent out-flow of the regulatory system. Because of the close interrelationship between the cardiovascular and respiratory controlling systems, aspects of developing postnatal regulation of the latter system are also being studied.
Three specific aims are being pursued: 1) age-related differences in sympathetic activity (both efferent discharge and plasma catecholamine levels), 2) characteristics of development of autonomic regulation of the heart (recordings from cardiac vagal motoneurons and use of HRP techniques to locate cardiac sympathetic postganglionic soma), 3) age-related changes in the respiratory rhythm generator (efects of various forcing inputs, e.g., lung inflation, chemoreceptor stimulation). Recordings will be obtained from Althesin anesthetized or decerebrate unanesthetized piglets of: efferent sympathetic activity (splanchnic, cervical sympathetic, renal), efferent phrenic discharge, cardiac vagal fibers, motoneurons in nucleurs ambiguus and ventrolateral nucleus ambiguus, aortic pressure, EKG, regional arterial blood flow (particularly renal, mesenteric) and appropriate marking pulses. The age-related effects of alterations in afferent discharge from various cardiovascular-respiratory receptors, e.g. cardiopulmonary, arterial baroreceptors, on central cardiovascular and respiratory controlling systems will be evaluated. Common periodicities in sympathetic discharge and periodicities related to the cardiac cycle (indicated by EKG) or central respiratory cycle (indicated by efferent phrenic discharge) are being revealed by cross correlation and power spectral analyses, particularly tests for power spectral equivalence and coherence. The effects of brain stimulation and of stresses such as hypercapnia, hypoxia and hemorrhage will also be evaluated. Age-dependency of results will be determined statistically in 6 age groups of piglets. The results will contribute to our understanding of circulatory adjustments to extrauterine environment and to our knowledge of the degree of regulation of cardiovascular function available in the neonate. Information will be obtained which is necessary for the understanding of reflexes involved in physiological adjustments to various stresses (hypercapnia, hemorrhage, hypoxia), relevant especially to the most vulnerable period in the life of the child.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL020864-08
Application #
3336295
Study Section
(SSS)
Project Start
1978-08-01
Project End
1987-07-31
Budget Start
1985-08-01
Budget End
1986-07-31
Support Year
8
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Suny Downstate Medical Center
Department
Type
Schools of Medicine
DUNS #
068552207
City
Brooklyn
State
NY
Country
United States
Zip Code
11203
Sica, Anthony L; Zhao, Ning (2006) Heart rate variability in conscious neonatal swine: spectral features and responses to short-term intermittent hypoxia. BMC Physiol 6:5
Sica, Anthony L; Ruggiero, David A; Hundley, Bruce W (2005) The cardiac-related rhythm in preganglionic sympathetic activities of developing piglets. Brain Res 1042:205-13
Ruggiero, D A; Zhao, N; Anwar, M et al. (2004) Organization of the newborn piglets vagal motor complex: insights into integrated autonomic control mechanisms. Auton Neurosci 115:41-53
Sica, Anthony L; Hundley, Bruce W (2004) Hypercapnia induces long-term changes in postganglionic renal nerve activity in the piglet. Auton Neurosci 111:97-109
Sica, Anthony L; Ruggiero, David A; Zhao, Ning et al. (2002) Developmental changes in heart rate variability during exposure to prolonged hypercapnia in piglets. Auton Neurosci 100:41-9
Zhao, Ning; Gootman, Phyllis M; Sica, Anthony L (2002) Baroreceptor-related dysrhythmias in piglets with selective autonomic denervation of the heart. Neurosci Lett 330:79-83
Khan, M S; Zhao, N; Sica, A L et al. (2001) Changes in R-R and Q-T intervals following cardiac vagotomy in neonatal swine. Exp Biol Med (Maywood) 226:32-6
Hundley, B W; Sica, A L; Gootman, P M (2001) Rhythmicities in sympathetic discharge: a signal of cardiorespiratory integration in developing animals. Ann N Y Acad Sci 940:416-30
Zhao, N; Khan, M; Ingenito, S et al. (2001) Electrocardiographic changes during postnatal development in conscious swine with cardiac autonomic imbalance. Auton Neurosci 88:167-74
Ruggiero, D A; Underwood, M D; Mann, J J et al. (2000) The human nucleus of the solitary tract: visceral pathways revealed with an ""in vitro"" postmortem tracing method. J Auton Nerv Syst 79:181-90

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