Effects of acute exposure to cold on pulmonary arterial blood pressure in awake rats.

This study examined alterations in the degree of exposure to cold and the pulmonary arterial pressure in awake, catheter-implanted rats. Seven male Wistar rats weighing 280 to 300 g were used. Two special hand-made catheters were inserted into the pulmonary artery and the level of the aortic arch, respectively. Each animal was exposed once to each of four cold temperatures, i.e. 5, 0, -5 and -10 degrees C, and 25 degrees C temperature. Acute cold exposures produced significant increases in pulmonary arterial pressure (p < 0.05). Pulmonary arterial pressure and the ratio of pulmonary arterial pressure to systemic arterial pressure increased gradually with exposure to decreasing temperatures (p < 0.05). These results indicate the possible significance of greater cold exposure in the increased occurrence of high altitude sickness, such as high altitude pulmonary edema. Further work is necessary to investigate the direct relation between cold-induced pulmonary arterial pressure increments and high altitude pulmonary edema.