Inhibition by 1,3-dipropyl-8(p-sulfophenyl)xanthine of the respiratory stimulation induced by common carotid occlusion in rats.

The effects of 1,3-dipropyl-8(p-sulfophenyl)xanthine (DPSPX) and enprofylline on the respiratory responses to bilateral occlusions of the common carotid arteries (CCO) were studied in rats anesthetized with sodium pentobarbitone and breathing spontaneously. CCO during periods of 5, 10 and 15 s caused increases in tidal volume (VT) and respiratory frequency (f) dependent on duration of the occlusions, these effects were markedly reduced after section of the carotid sinus nerves. Transient increases in systemic arterial blood pressure (BP) associated with the ventilatory effects of CCO were also observed. Intracarotid infusions of DPSPX (100 nmol/min, for 3 min) but not of enprofylline (100 nmol/min, for 3 min) decreased the respiratory stimulation induced by CCO without modifying significantly the increases in BP. It is concluded that adenosine may be involved in the ventilatory responses to CCO that are mediated by carotid body chemoreceptors.