Postganglionic sympathetic discharge in neonatal swine.
We hypothesized that cardiac and respiratory modulation of postganglionic peroneal activity appeared in an age-related manner. In anesthetized, paralyzed and artificially ventilated piglets, simultaneous recordings of efferent phrenic and peroneal discharges were obtained during hyperoxia (fraction of inspired oxygen, FiO2 = 1.0) and hypoxia (FiO2 = 0.1). Spectral analyses of peroneal and aortic blood pressure signals revealed peaks at the cardiac frequency (3.25-5.0 Hz). Coherence analysis showed that these two signals were highly correlated at those frequencies, providing evidence for baroreceptor entrainment. Statistically significant (p < 0.05) increases of coherence values were observed during hypoxic stimulation. Such results were observed in most animals despite age, and provided evidence of a potent mechanism for insuring vasomotor tone even in newborn animals. In contrast, spontaneous respiration-related peroneal discharges were observed only in animals > or = 20 d old. In animals < 20 d old, hypoxic stimulation elicited respiration-related discharges in peroneal activity. In many cases, peroneal hypoxic discharges exhibited an immature biphasic response pattern despite the presence of a mature response pattern of phrenic activity. Such findings suggest a developmental lag in the linkages of respiratory and sympathetic controlling networks.
Sica
A L
AL
Department of Pediatrics, Clinical Campus of the Albert Einstein College of Medicine, New Hyde Park, New York 11042, USA.
Hundley
B W
BW
Gootman
P M
PM
D000818:Animals; D000831:Animals, Newborn; D004195:Disease Models, Animal; D005728:Ganglia, Sympathetic / Q000502:physiology*; D018496:Hyperoxia / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D010543:Peroneal Nerve / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D013552:Swine