Correlation of ventricular mechanosensory neurite activity with myocardial sensory field deformation.

The mechanosensory activity generated by ventricular epicardial sensory neurites associated with afferent axons in thoracic sympathetic nerves was correlated with sensory field deformation (long axis, short axis, and transmural dimension changes), regional intramyocardial pressure, and ventricular chamber pressure in anesthetized dogs. Ventricular mechanosensory neurites generated activity that correlated best with strain developed along either the long or short axis of their epicardial sensory fields in most instances. Activity did not correlate normally to local wall thickness or to regional wall or chamber pressure development in most cases. During premature ventricular contractions, the activity generated by these sensory neurites correlated best with maximum strain developed along at least one sensory field epicardial vector. Identified sensory neurites were also activated by local application of the chemical bradykinin (10 μM) or by local ischemia. These data indicate that the activity generated by most ischemia-sensitive ventricular epicardial sensory neurites associated with afferent axons in sympathetic nerves is dependent on not only their local chemical milieu but on local mechanical deformation along at least one epicardial vector of their sensory fields.