The present investigation was undertaken to investigate the influence of hypercapnia on intrapulmonary neuroepithelial bodies (NEB). Rabbits were mechanically ventilated with a hypercapnic gas mixture (7% carbon dioxide, 20% oxygen, 73% nitrogen). Lung samples were examined by a microspectrographical analysis of the NEB formaldehyde-induced fluorescence to quantify the cytoplasmic 5-hydroxy-try...

Three children and two young adults with severe asthma who had frequent episodes of respiratory failure were studied. Isocapnic hypoxia and hyperoxic hypercapnia were produced separately using a rebreathing apparatus. Alveolar carbon dioxide tension and oxygen tension were estimated by continuously sampling expired gases. The three young children had a diminished response to hypoxia but a norma...

It has been proposed that the responses of the cerebral circulation to hypoxia, hypercapnia and hypotension may be partially mediated by an autonomic reflex with receptors in the carotid body or sinus serving as sensors and the efferent limbs being the 7th cranial nerves. Transection of the 7th cranial nerve has been reported to impair the cerebral circulatory response to isolated chemoreceptor...

This investigation tests the hypothesis that the normal cerebral image obtained non-invasively during continuous inhalation of C15O2 is related to cerebral blood flow. Trace amounts of CO2 labeled with the positron-emitting radionuclide 15O were administered to 4 normal subjects at normo- and hypocapnia and to 2 of these subjects at hypercapnia. Hypocapnia typically caused a marked decrease in ...

Severe hypercapnia can be predicted by a decrease in cerebral electrical activity. The authors describe a sudden decrease in spectral entropy due to severe hypercapnia-induced respiratory acidosis in a patient with chronic pulmonary obstructive disease during lung resection. After two and a half hours of low tidal volume ventilation in the lateral position, the state entropy suddenly dropped fr...

This investigation tests the hypothesis that the normal cerebral image obtained non-invasively during continuous inhalation of C"O, is related to cerebral blood flow. Trace amounts of CO, labeled with the positron-emitting radionuclide " 0 were administered to 4 normal subjects at normoand hypocapnia and to 2 of these subjects at hypercapnia. Hypocapnia typically caused a marked decrease in cer...

A 21 yr old with deep breathing and awake apnoea, who had recurrent hypoxaemia and hypercapnia without sleep apnoea, was presented. Although the organic abnormality responsible for the breathing disturbance was not found, administration of acetazolamide facilitated several breaths between sighs, and the patient's hypoxaemia with hypercapnia improved. Some patients who have abnormalities in the ...

The ventrolateral medulla (VLM) functions as a primary central chemoreceptive area, responsible for sensitivity to increases in arterial levels of PCO2 and mediating the ventilatory response to hypercapnia (Loeschcke, 1982). ATP acting via P2X receptors may be involved in mediating changes in the activity of medullary respiratory neurones during hypercapnia, thus playing an important role in ce...

Introduction An effective non-invasive method of assessing spinal function would be of great clinical importance. However, a better understanding of neurovascular coupling in the spinal cord is needed for a reliable use of the BOLD technique in a clinical context. In recent studies, hypercapnia was used as a control stimulus to study the sensitivity of BOLD responses in the spinal cord [1,2]. H...

It has been proposed that decreases in nasal resistance (Rn) during hypercapnia are entirely due to vasoconstriction in the nasal cavity. We hypothesized that alae nasi (AN) muscle activity dilates the nasal vestibule and contributes to the decrease in Rn during hypercapnia. Nine normal subjects were studied during hyperoxic hypercapnia (HH). Rn and vestibular resistance (Rvest) for one nasal p...