Effects of cyanide and doxapram during panting

Abstract

The ventilatory responses, blood gases and acid-base status to intravenous injections of KCN and doxapram hydrochloride were studied in anesthetized dogs during normothermia and thermally induced panting. In the normothermic animal, KCN evoked elevation of VE (154.7%), VT (70.1%), f (48.3%, PaO2 (12.1%) and pH (0.098 units), while PaCO2 diminished by 9.7 mm Hg. During panting, KCN infusions resulted in increases of VE (24.5%), VT (46.6%), PaO2 (3.9%) and pH (0.034 units), while f decreased (10.1%). Bolus injections of doxapram during normothermia increased VE (32.6%), VT (18.8%) and f (17.1%). During panting VE, VT and f increased by 18.0%, 18.2% and 1.5%, respectively. These results demonstrate that the peripheral (arterial) chemoreceptors preserve the capacity to react to acute chemical stimuli in animals in which the thermal stimuli override the normal chemical control of respiration in order to control body temperature, and that this reaction contributes to the integrated respiratory drive.