Figure 2.

(A) Exponential decay is fit to HRR from sympathetic stimulation in anesthetized dogs (data digitized from graph of Warner and Cox).26 (B) Heart rate recovery (normalized) of healthy subjects during control, atropine, propranolol, and double blockade (data digitized from graph of Savin et al.).2 The propranolol curve is fit with exponential decay, whereas the atropine curve is fit with a sigmoidal curve for sympathetic withdrawal. (C) The sigmoidal curve is fit to heart transplant patients recovering from exercise, with normal control recovery included for contrast (data digitized from graph of Savin et al.2