Integrated cardiovascular responses to combined somatic and visceral afferent stimulation in newborn piglets

Mean aortic pressure, arterial flow and heart rate response to interactions of afferent stimulation of the sciatic nerve (SNS) and carotid sinus stimulation by infusion (CSI) or inhibition by bilateral common carotid occlusion (BCCO) were studied in 25 newborn piglets under halothane-N2O anesthesia. Combined stimulation of the somatic and visceral afferents produced no heart rate changes. Combinations of pressor stimuli (BCCO and high frequency SNS) showed facilitation; femoral and renal resistances increased. However, combinations of depressor stimuli (CSI and low frequency SNS) showed occlusion. In combinations of pressor with depressor stimuli, the pressor pattern of responses dominated. Thus, dissimilar types of excitatory afferent inputs are capable of evoking facilitation in the neonatal cardiovascular regulatory system.