Modulation of duck intrapulmonary chemoreceptor discharge by cardiac activity

A previous study on duck intrapulmonary chemoreceptors (IPC) reported that the cardiac cycle modulated discharge of most IPC, but did not distinguish whether pulsatile blood flow or cardiac-linked fluctuation in parabronchial gas flow was responsible. In this study with Pekin ducks one of 14 IPC recorded was found to be modulated by cardiac activity in the perfused lung, and none in the non-perfused lung. Discharge variability expressed as coefficients of variation did not change with pulmonary artery ligation. It is concluded that: (1) pulsatile blood flow does not affect discharge regularity of most IPC and (2) the infrequent occurrence of cardiac modulation of IPC in thoracotomized ducks may be the result of IPC having receptive endings near the parabronchial lumen.