Role of sinoaortic baroreceptors in initiating the renal response to continuous positive-pressure ventilation in the dog.

Experiments were conducted to determine the role of cardiopulmonary receptors with vagal afferents and sinoaortic baroreceptors in initiating the reflex antidiuresis and antinatriuresis during continuous positive-pressure ventilation (CPPV). CPPV was applied to 18 dogs: seven control, five that underwent bilateral vagotomy; and six that underwent sinoaortic baroreceptor denervation. The dogs were anesthetized with pentobarbital, paralyzed with succinylcholine, and their lungs were mechanically ventilated with a volume ventilator. Renal function and systemic hemodynamics were monitored by clearance methods and pressures, respectively. After two 30-min control periods of intermittent positive-pressure ventilation (IPPV), CPPV using 10 cm H2O positive end-expiratory pressure was applied for two 30-min experimental periods. Three 30-min recovery periods of IPPV followed. In dogs of the control group and vagotomy group, CPPV caused statistically significant decreases from control levels in urinary flow, sodium excretion, and glomerular filtration rate. However, in the dogs of the sinoaortic baroreceptor denervation group, CPPV did not produce any significant change in these variables. Therefore, the results do not support the hypothesis that cardiopulmonary receptors mediate the renal response to CPPV. Rather, the data indicate that the aortic arch and carotid sinus baroreceptors participate in initiating the reflex antidiuresis and antinatriuresis during CPPV.