Biomedical subjects

J M Colacino

Publications and source records attributed to J M Colacino.

39 records · Page 3Linked to original sources

PubMed1977

Respiratory responses of ducks to simulated altitude.

Domestic ducks were exposed to simulated altitudes of 0, 3000, 6000, and 9000 m in order to study the respiratory changes that take place. We found that the respiratory minute volume (VE,BTPS) increased with altitude, the increase being due to increased respiratory frequency while tidal volume (VT, BTPS) showed only minor changes. The quantity of air moved (VE, STPD), however, remained nearly unchanged with increasing altitude. The oxygen extraction, calculated as 1--(FIN2FEO2)/(FEN2FIO2), remained constant at about 0.28 up to 6000 m and declined to 0.17 at 9000 m. The fractional gas concentrations (FO2 and FCO2) in exhaled air and in the interclavicular and posterior thoracic air sacs changed only little up to 6000 m, but at 9000 m FO2 increased and FCO2 decreased. The relative constancy of expired and air sac gas up to 6000 m seems remarkable. However, when applied to current models of air flow in the avian respiratory system the results seem fully explainable and permit a detailed analysis of the functioning of the avian respiratory system.

Adaptation, Physiological↗

PubMed1977

Effect of arterial carbon dioxide on cerebral blood flow in ducks.

The purpose of this study was to determine the effect of arterial PCO2 on blood flow to the avian brain. Cerebral blood flow was measured on curarized, artificially ventilated Pekin ducks by the rate at which intra-arterially injected xenon-133 was cleared from the duck's brain. A two-component clearance curve resulted: the blood flow calculated from the fast and slow components was similar to the blood flow to mammalian grey and white matter, respectively. Hypercapnia markedly increased the fast component of blood flow, whereas hypocapnia had no effect on this component. These effects were not due to changes in blood pressure, which was independent of arterial PCO2. Blood flow calculated from the slow component was independent of arterial PCO2. We conclude that the lack of response to hypocapnia may contribute to the exceptional tolerance of birds to high altitude by maintaining normal cerebral blood flow.

Animals↗

PubMedDate not supplied

Peritoneal oxygenation of normoxic and hypoxic dogs.

The ability of an oxygen saturated fluorocarbon, perfluorodecalin (C10F18), to raise the arterial partial pressure of oxygen (PaO2) of anesthetized dogs, was tested by peritoneal lavage in normoxic and hypoxic animals. While breathing room air, five of six animals showed an increased PaO2 of 5-10 torr above reference values. In cases of mild hypoxia, increases of 5-25 torr were observed. No increase in PaO2 was seen when hypoxia was severe. A mathematical model was used to analyze the data and determine a transport coefficient (k). Calculated k values were 1.18 +/- 0.151 ml O2 STPD per minute for normoxic animals and 0.91 +/- 0.180 ml O2 STPD per minute for hypoxic animals, respectively. The estimated transport coefficients are small and indicate that physiologically significant amounts of O2 cannot be delivered by the proposed method under the experimental conditions used. The low k values were attributed to long diffusion distances and small effective surface areas in the abdominal cavity.

Animals↗