effects of acute systemic hypoxia on the cardiovascular system (cys) and respiration of spontaneously breathing cats were studied in two conditions. 1): hypoxic air (6-8% 02 in n2) was given to the animal to induce systemic hypoxia for 20 minutes. hyperventilation at this condition lowered arterial c02 tension (pac02 hypocapnia). 2): in the second run, induction of hypocapnia was prevented by a...

effects of acute hypercapnia on the cardiovascular system (cys) were studied in the anesthetized cat. after surgery the animal was exposed to a gas mixture of 12% co2 and 25% o2 in nitrogen, and hypercapnia with low levels of arterial ph (pha) was produced for 20 minutes. in the second run the same level of hypercapnia was induced by ventilating the same cat from the above gas mixture but pha w...

the purpose of this study was to investigate the potential responses of the cardiovascular system and regional blood flow to hypoxic hypoxia (bb) and to carbon monoxide (co)-induced hypoxia (coh). ten anesthetized cats were studied under two nonnoxic (control: cont) and two hypoxic conditions. four types of radioactive micro spheres were used to measure regional blood flow during cont and two h...

The stimulation of arterial baroreceptors (blind sack technique) inhibited the preganglionic and postganglionic cardiac sympathetic activity. There were found three populations of single sympathetic preganglionic fibers (Th3) responding in a different way to the stimulation of arterial baroreceptors and arterial chemoreceptors (infusion of the small volume of saline bubbled with CO2 into the ca...

The purpose of this study was to determine whether the level of arterial pressure and degree of baroreceptor activation affect responses to stimulation of chemoreceptors. Chemoreceptors were stimulated by injecting nicotine into the common carotid artery of anesthetized and paralyzed dogs. Responses were observed in the innervated gracilis muscle, perfused at constant flow while perfusion press...

Dopamine is present in the carotid body and has been postulated to be an inhibitory neurotransmitter. The purpose of this study was to determine the effects of dopamine on ventilation in man and to examine its mechanism of action. Dopamine (0.5-10 mug/kg per min) was infused in eight normal men at different levels of arterial chemoreceptor activity, produced by varying the inspired Po(2). Durin...

The peptidergic innervation of arterial chemoreceptor organs (the rat carotid body and vagal paraganglia; guinea pig carotid body) was studied immunohistochemically. Five different populations of nerve fibres in the guinea pig carotid body could be discriminated according to their origin and their chemical coding. The innervation pattern of the rat carotid body differed in some aspects. Compari...