Pulmonary Vasomotor Responses of Isolated Perfused Cat Lungs to Anoxia and Hypercapnia

Abstract

RECENT observations in the intact animal indicate that a decrease in 02 concentration in the inspired air may act, as does CO2, on the pulmonary vessels to produce constriction [for references see Duke, 1949 a; Dirken and Heemstra, 1949 a, b, c; Nisell, 1950]. Isolated perfused lungs provide a means of determining whether these effects are independent of neuro-humoral reflexes. When this investigation was begun, Lohr [1924] had used this technique to study pulmonary vasomotor responses of the cat in response to anoxia and hypercapnia. The same problem had been investigated in anaesthetized cats [Retzlaff, 1913;Wearn, Ernstene, Bromer, Barr, German and Zschiesche, 1934;Von Euler and Liljestrand, 1946; Logaras, 1947] and in the cat heart-lung preparation [Drinker, Churchill and Ferry, 1926]. The results considered in the present paper dealing with the effects of 02 and CO2 on the isolated lungs of this species were briefly reported [Duke, 1949[Duke, b, 1950 earlier. Since this investigation was begun, Nisell [1948Nisell [ , 1950 has reported the results of a similar study. METHODS.Isolated cat lungs were set up and perfused using essentially the same technique as that described by Daly [1938] for the lungs of dogs. Cats weighing more than 2-0 kg. were anaesthetized with intraperitoneal pentobarbitone (0.03 g./kg.) or chloralose (0.1 g./kg.) and bled from the carotid artery until death occurred. Heparin (1000 I.U. "Liquemin," Roche) was injected intravenously before bleeding, and 1000-1500 J.U. were added subsequently to each 100 c.c. blood collected. Artificial ventilation (Starling "Ideal" pump) was maintained during bleeding and subsequent dissection. Cannulw were inserted into the trachea, the left auricle and the pulmonary artery, and the ventricles were compressed by tying them tightly with tape. When positive pressure ventilation was used during perfusion the lungs and heart were left in situ, but when negative pressure ventilation was used they were removed from the chest.

The viability of premature lambs

“…It is therefore possible that the additional increase in pulmonary vascular conductance which was seen when the lungs 203 204 G. V. R. BORN, G. S. DAWES AND JOAN C. MOTT were ventilated with air, after ventilation with nitrogen, may have been due to the removal of vasoconstrictor substances formed in the absence of sufficient oxygen. Alternatively the phenomenon may be related to that observed by Nisell (1948Nisell ( , 1950 and Duke (1951Duke ( , 1954 in the isolated perfused lungs of cats and ascribed to changes in the oxygen tension of the alveolar air or the perfusate.…”

Effects of Breathing Carbon Dioxide upon the Pulmonary Circulation

“…5 of the 15 patients had increases in flow that exceeded 0.48 liter per minute per square meter of body surface; this value had been previously calculated in this laboratory as representing the limit of variation that might, with 95 per cent confidence, be anticipated to occur between successive Fick measurements.9 These patients (E.C., P.G., W.B., B.S., and J.S.) also had the largest increases in oxygen uptake, ranging from 11 to 30 per cent; indeed, the largest increment in flow of +41 per cent occurred in patient J.S., who showed the largest increment in oxygen uptake (+30 per cent).…”

The Effect of Breathing 100% Oxygen on the Pulmonary Arterial Pressure in Patients With Pulmonary Tuberculosis and Mitral Stenosis 1

“…Possibly the effect of oxygen at this altitude is to abolish the slight relative anoxemia which normally exists here. If this is the case one might observe a less marked response at sea level or even no response at all (8).…”

“…This effect has been attributed to a local action of the anoxic mixture on the blood vessel walls resulting in a constriction of the pulmonary arterioles and pre-capillaries and an increase in pulmonary arterial pressure. Vagotomy and stellate ganglionectomy do not change the vascular response to the breathing of anoxic mixtures in the cat (1).The effect of breathing 100% oxygen on the pulmonary arterial pressure has been investigated in animals (1,3,4,8) but not adequately in man. Euler and Liljestrand (1) found that pure oxygen caused a fall in the pulmonary arterial pressure of cats which did not appear to these investigators to be the result of decreased blood flow, but rather to a dilatation of the pulmonary vasculature.…”

“…The effect of breathing 100% oxygen on the pulmonary arterial pressure has been investigated in animals (1,3,4,8) but not adequately in man. Euler and Liljestrand (1) found that pure oxygen caused a fall in the pulmonary arterial pressure of cats which did not appear to these investigators to be the result of decreased blood flow, but rather to a dilatation of the pulmonary vasculature.…”