ABSTRACT
The effects of hypoxia and air microembolism on pulmonary pressor response and lung fluid exchange were studied in eight conscious goats with chronic lung lymph fistula. The results indicate: (1). The site of pulmonary vasoconstriction induced by hypoxia may be precapillary. Hypoxia (4000m-simulated high altitude) induces no pulmonary microvascular injury. (2). Air microembolism results in elevation in Ppa and increase in pulmonary microvascular permeability, (3). Air microembolism in hypoxic animal induces further increase in Ppa. But the amplitude of pressor response induced by hypoxia in combination with air microembolism is not the summation of those induced by either of them acting separately. (4). Hypobaric hypoxia(4000m-simulated high altitude) does not aggravate air microembolism-induced lung injury.
ABSTRACT
This paper is to report our results of the observation on the changes of the pulmonary water content of the rats and mice after their exposure to a simulated altitude of 6000 meters above sea level for seven days.It was found that the changes of the pulmonary water content varied with the duration of exposing to the high altitude. It was lower than the control value on the first day of exposure, and then it increased approaching or even being a little higher than the control value on the second and third day. But it decreased and was below the control value again from the fourth day to the seventh day. The lung weight was increasing continuously in the same period.In addition, there were progressive increase of both the wet-lung/body and dry-lung/body indices, progressive decrease of left/right ventricles ratio, and gradual rising of hemoglobin in the animals studied.
ABSTRACT
Rats were made to bleed and about 40% of the total blood volume was lost. A replacement of Ringer's solution of the volume four times the lost blood volume was given and the animals were closely monitored for 24 hours. The hemoglobin level of the animals was low throughout the course of observation. The plasma colloid osmotic pressure reached the lowest point 15 minutes after bleeding, and then gradually rising up returned to a level about 90% of the control value at the end of 24 hours. The relativity between the plasma colloid osmotic pressure and the lung water content was quite significant in those rats in a low altitude environment (P0.05).The result indicates that the increased lung water content due to decreased plasma osmotic pressure could not be made further worse by hypoxia due to high altitude. The characteristic pulmonary hemodynamic changSs caused by hypoxia might be considered as the explanation of the phenomenon.