title: Cerebral autoregulation is minimally influenced by the superior cervical ganglion in two- week-old lambs, and absent in preterm lambs immediately following delivery.
abstract: Cerebral vessels in the premature newborn brain are well supplied with adrenergic nerves, stemming from the superior cervical ganglia (SCG), but their role in regulation of blood flow remains uncertain. To test this function twelve premature or two-week-old lambs were instrumented with laser Doppler flow probes in the parietal cortices to measure changes in blood flow during changes in systemic blood pressure and electrical stimulation of the SCG. In lambs delivered prematurely at ∼129 days gestation cerebral perfusion and driving pressure demonstrated a direct linear relationship throughout the physiologic range, indicating lack of autoregulation. In contrast, in lambs two-weeks of age, surgical removal of one SCG resulted in ipsilateral loss of autoregulation during pronounced hypertension. Electrical stimulation of one SCG elicited unilateral increases in cerebral resistance to blood flow in both pre-term and two-week-old lambs, indicating functioning neural pathways in the instrumented, anesthetized lambs. We conclude cerebral autoregulation is non-functional in preterm lambs following cesarean delivery. Adrenergic control of cerebral vascular resistance becomes effective in newborn lambs within two-weeks after birth but SCG-dependent autoregulation is essential only during pronounced hypertension, well above the normal range of blood pressure.
authors.affiliation: Department of Pediatrics, Division of Neonatology, Loma Linda University School of Medicine, Loma Linda, California, United States of America.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Czynski
authors.affiliation: Department of Respiratory Care, Pulmonary Physiology Laboratories, Loma Linda University Medical Center, Loma Linda, California, United States of America.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Terry
authors.affiliation: Department of Pediatrics, Division of Neonatology, Loma Linda University School of Medicine, Loma Linda, California, United States of America.
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Deming
authors.affiliation: Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California, United States of America.
authors.forename: Gordon G
authors.initials: GG
authors.lastname: Power
authors.affiliation: Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, California, United States of America.
authors.forename: John N
authors.initials: JN
authors.lastname: Buchholz
authors.affiliation: Department of Pediatrics, Division of Neonatology, Loma Linda University School of Medicine, Loma Linda, California, United States of America ; Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California, United States of America.
authors.forename: Arlin B
authors.initials: AB
authors.lastname: Blood
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001794:Blood Pressure; D001921:Brain / Q000098:blood supply / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D036861:Delivery, Obstetric; D004558:Electric Stimulation; D006454:Hemoglobins / Q000378:metabolism; D006706:Homeostasis; D047928:Premature Birth / Q000503:physiopathology*; D034561:Sheep, Domestic / Q000502:physiology*; D017783:Superior Cervical Ganglion / Q000502:physiology*
chemical_list: D006454:Hemoglobins