PHYSIOLOGICAL-RESPONSES TO TREADMILL EXERCISE AND AMBIENT-TEMPERATURE IN NORMAL AND MALIGNANT HYPERTHERMIA SUSCEPTIBLE PIGS

  • 1 January 1986
    • journal article
    • research article
    • Vol. 50  (1) , 78-83
Abstract
Ten susceptible and ten resistant pigs to malignant hyperthermia were used to observe the effects of exercise and ambient temperature on selected physiological parameters. Pigs were submitted to a ten minute exercise on a treadmill operating at a speed of 1.8 km/h and inclined to 11.degree.. Exercise in the first group was at an ambient temperature of 14.degree. C, and in the second at 29.degree. C. The right carotid artery was previously cannulated for blood pressure measurements and for repeated blood sampling during exercise. Arterial pressure, heart rate, rectal and cutaneous temperatures were recorded. Levels of cortisol, creatine kinase and its isoenzymes were measured. At 14.degree. C, exercise caused some physiological adjustments in susceptible animals; heart rate, skin temperature and cortisol levels incresed (P < 0.05). In resistant pigs, only the heart rate was elevated significantly following exertional stress at 14.degree. C. Exercise at 29.degree. C produced severe stress and marked physiological changes: heart rate, rectal and skin temperatures and cortisol levels increased significantly in both susceptible and resistant swine. At 29.degree. C, susceptible pigs also had higher levels of serum cortisol, total creatine kinase and MM isoenzyme (P < 0.05) compared to resistant pigs. The results indicate that, following exertional or thermal stress, susceptible pigs undergo more extensive physiological changes than do resistant pigs. Similar levels of stress prior to slaughter may trigger physiological changes which in the susceptible pigs would likely result in pale, soft exudative myopathy.