Effects of LL-VNS on SGNA and heart rate (HR). A, Chronic LL-VNS significantly reduced SGNA over 24 hrs. The SGNA normalized to baseline level after cessation of LL-VNS. B, Hourly averages of SGNA show that the reduction in integrated SGNA was particularly striking at 8 AM. All values are averaged over 5 days and 6 dogs. C, The administration and cessation of chronic LL-VNS did not change the overall heart rate. D, Hourly averages of heart rate reveal that the morning surge of heart rate (arrowhead) was markedly attenuated during LL-VNS. HR, heart rate. * P<0.05.