Age-Dependent Cardiovascular Effects of Afferent Stimulation in Neonatal Pigs

Postnatal development of heart rate (HR), mean aortic pressure and arterial flow responses to carotid baroreceptor stimulation (CS) or inhibition (BCCO), and to sciatic nerve stimulation (SNS), was studied in 60 newborn piglets under halothane-N<sub>2</sub>O anesthesia. There was no HR change in most piglets during CS or BCCO, but tachycardia was observed during high frequency or intensity SNS and after bilateral vagotomy. In younger animals, smaller pressor effects were observed during high frequency or intensity SNS than in older ones. There were also age-dependent changes in femoral and renal flows and resistances to CS, BCCO, SNS or bilateral vagotomy. The results indicate postnatal maturation of regulatory mechanisms for HR and peripheral flow.