Enhanced responsiveness of cardiac vagal chemosensitive endings to bradykinin in heart failure

Irving H. Zucker. Enhanced responsiveness of cardiac vagal chemosensitive endings to bradykinin in heart failure. Am. J. Physiol. 273 (Regulatory Integrative Comp. Physiol. 42): R637-R6451997.-There is good evidence that the cardiopul-monary and arterial baroreflexes are blunted in chronic heart failure (HF). Other evidence, however, suggests that the cardiac chemoreflex is enhanced during HF. In the present study, we sought to determine whether HF alters the sensitiv-ity of cardiac vagal chemosensitive endings to bradykinin (BK), an endogenous mediator that activates ventricular C fiber afferents. We measured the activity of cardiac vagal single fibers and compared the afferent responses to left atria1 injections of BK and capsaicin in sham-operated and pacing-induced HF dogs. The capsaicin-sensitive endings did not respond to changes in cardiac pressures evoked by vascula