Although power spectra of R-R and P-R intervals in response to random respiration show similar frequency distributions, the way in which dynamic sympathetic regulation contributes to such similarity remains unknown. We estimated the transfer function from sympathetic stimulation to the atrioventricular interval (AV conduction time; T_AV) with and without constant atrial pacing in seven anesthetized cats. The transfer function from sympathetic stimulation to T_AV, except for absolute gain values, approximated a low-pass filter similar to that from sympathetic stimulation to the A-A interval (heart period; T_AA). The 90%-rise times did not differ between the T_AA and T_AV step responses (32.3 ± 1.8 vs. 29.6 ± 3.2 s). Constant pacing augmented the T_AV step response (0.58 ± 0.10 vs. 0.86 ± 0.12 ms/Hz, P < 0.05) without affecting the 90%-rise time. These findings suggest that the dynamic characteristics of sympathetic control are similar between T_AA and T_AV despite the different electrophysiological mechanisms determining T_AA and T_AV. A numerical simulation indicated that if the dynamic characteristics of the sympathetic control do not match between T_AA and T_AV, a critical condition for initiation of reentrant tachycardia would be encountered.