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Impedance pneumography, electrical impedance measurements of the lung, is a technique which has been widely used to monitor respiration non-invasively and more recently, the onset of pulmonary oedema. Attempts have been made to try to localise the changes in impedance using electrode arrays and electrode guarding. These techniques allow localisation to a(More)
The mammalian respiratory tract contains innervated groups of endocrine cells which are believed to respond to hypoxia. We have demonstrated the involvement of a specific regulatory peptide produced by the cells, calcitonin gene-related peptide (CGRP), in this response. Cells immunoreactive for CGRP or for protein gene product 9.5 (PGP 9.5), a general(More)
An electrical impedance tomographic imaging system has been developed which can monitor changes in the resistivity of the thorax at a rate of 5 frames per second. There is a high correlation (r greater than 0.95) between changes in resistivity of the lungs and the volume of air inspired. Calibration of the system allows continuous monitoring of the level of(More)
Applied potential tomography (APT) images can be collected at a rate of 24 per second and data collection can be synchronised with the ECG. Images thus obtained from a thoracic plane allow the spatial separation of impedance changes originating in the heart, aorta and lungs and have raised the possibility of detecting pulmonary perfusion abnormalities from(More)
Rats subjected to 10% O2 (hypoxic rats) for various periods and recovery regimens were compared with control animals with respect to pulmonary artery pressure (Ppa), right ventricular hypertrophy (RVH), and muscularisation of small pulmonary vessels. Mean Ppa was measured in anaesthetised animals spontaneously breathing air and rose from 16 mmHg in controls(More)
The rat model of chronic hypoxic pulmonary hypertension has been extensively studied and shows many of the features seen in man with chronic pulmonary hypertension. The development and reversibility of these changes by various treatments and by drugs is discussed. The experimental model may provide valuable clues as to the mechanisms involved in the(More)
High hemoglobin affinity for O2 [low PO2 at 50% saturation of hemoglobin (P50)] could degrade exercise performance in normoxia by lowering mean tissue PO2 but could enhance O2 transport in hypoxic exercise by increasing arterial O2 saturation. We measured O2 transport at rest and at graded levels of steady-state exercise in tracheostomized dogs with normal(More)
Ventilation to one lobe of lung was reduced in anaesthetized open-chest cats and dogs to simulate the ventilation/perfusion (V/Q) mismatching of chronic lung disease. Blood flow to this lobe fell less than ventilation; thus lobar V/Q diminished. In seven cats almitrine (0.5 mg/kg + 10 micrograms/kg per min, i.v.) caused a rise in pulmonary artery pressure(More)
Almitrine bismesylate is a peripheral chemoreceptor agonist. When given intravenously to anaesthetized rats it results in a reversible diuresis and natriuresis. The effect is abolished by denervation of the carotid bodies and is still present following vagotomy, when the animal is paralysed and artificially ventilated or following bilateral adrenalectomy.(More)