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Biomedical subjects

B A Waaler

Publications and source records attributed to B A Waaler.

At least 37 records · Page 2Linked to original sources
PubMed1970

The cite of action of nerves in the pulmonary vascular bed in the dog.

1. The effects of stimulation of the thoracic vagosympathetic nerve or upper thoracic sympathetic chain on the pulmonary vascular resistance have been studied in atropinized, isolated, ventilated lung lobes under various conditions of pulmonary circulation perfusion. Throughout the nerve-stimulation tests bronchial circulation perfusion was maintained or temporarily interrupted.2. The pulmonary vascular resistance increase evoked by nerve stimulation (a) occurred in the absence of tidal air changes; (b) did not consistently differ during predominantly ;sluice' and ;non-sluice' conditions of pulmonary circulation perfusion; (c) was approximately one and a half times greater during constant pressure than during constant volume inflow perfusion of the pulmonary circulation; and (d) was greater during reverse than during forward perfusion.3. In lung lobes perfused in either direction at constant volume inflow nerve stimulation produced an increase in inflow pressure and a diminution in total lung blood volume reflected by a temporary increase in blood outflow.4. In lung lobes in which neither the pulmonary nor the bronchial circulations were perfused and the capillaries were completely blocked by high intratracheal pressures, thus isolating the pulmonary arterial system from the venous system, nerve stimulation produced a diminution in the blood volume of both systems.5. Nerve stimulation produced a rise in bronchial arterial pressure in the absence of pulmonary circulation perfusion.6. Further evidence is adduced that pulmonary vasomotor nerve responses do not depend upon the transfer of transmitter substances from the bronchial to the pulmonary circulation.7. The possible significance of these observations in relation to the site of action of pulmonary vasomotor nerves is discussed.

Animals↗
PubMed1969

Transvascular fluid balance in the lung.

1. The transvascular fluid balance has been studied in isolated blood-perfused lungs of rabbit and cat. During periods of left atrial pressure (LAp) elevation, changes in preparation weight were measured. In some experiments simultaneous recordings of changes in blood volume, as judged by changes in emitted radioactivity from (51)Cr labelled red blood cells, were performed.2. In nine out of eleven experiments, elevation of LAp by 5 mm Hg within a test period of 8 min resulted in new weight stability and thus apparently in the establishment of a new transvascular fluid equilibrium. In five of these eleven experiments weight stability was also obtained on elevation of LAp by 10 mm Hg. When LAp was elevated further, transvascular fluid equilibrium was not obtained, and a continuous and eventually progressive outward flux of fluid occurred.3. In a preparation with the vasculature paralysed by papaverine in order to avoid vasomotor reactions, changes in plasma protein content caused immediate alterations in the weight slopes of the preparations. These alterations were interpreted as being due to changes in transvascular fluid transfer. Again new stable weights were obtained on moderate changes in plasma protein content.4. New weight and transvascular fluid equilibria seemed to be reached as a result of very small transvascular fluxes of fluid. The transvascular fluid balance in the lung may thus be dynamically maintained as a result of such small fluxes of fluid. The Starling hypothesis could account for this balance, provided that a small shift of fluid can cause sufficiently marked alterations in the osmotic and/or hydrostatic pressure gradient across the wall of the exchange vessels.5. The possible role of a small extravascular compartment with a high fluid colloid osmotic pressure is discussed in relation to transvascular fluid balance in the lung.

Animals↗
PubMed1968

Conditions governing the pulmonary vascular response to ventilation hypoxia and hypoxaemia in the dog.

1. Isolated lung lobes of the dog perfused through the pulmonary circulation only with atropinized autologous blood obtained by bleeding out the animal under general anaesthesia or following premedication with morphine hydrochloride were subjected to repetitive tests of ventilation hypoxia, the control and test gas mixtures containing similar concentrations of CO(2).2. The pulmonary vasomotor response to ventilation hypoxia depended upon the temperature of the perfusate and the time which had elapsed from the death of the animal to the start of perfusion, termed the ;ischaemic period'. The higher blood temperatures and shorter ischaemic periods favoured a pulmonary vasopressor response to hypoxia, and the lower temperatures and longer ischaemic periods a vasodepressor response or an absence of response.3. The vasopressor responses to hypoxia were associated with a rise in the pH (average, 0.09 in 5 experiments) and a fall in the P(CO2) of the blood. There were no consistent changes in the pH and P(CO2) of the blood accompanying vasodepressor responses.4. The vasopressor responses could be obtained over periods of perfusion lasting 4 hr or longer.5. It is suggested that changes in the composition of blood equilibrated in the isolated perfused lung cannot be predicted from in vitro dissociation curves.

Animals↗