STRUCTURAL AND METABOLIC CHANGES IN SKELETAL-MUSCLE OF COLD-ACCLIMATED RATS

1. The effects of long-term (8 weeks), intermittent (16 h daily), cold exposure (4-5 +/- 1 degrees C) on pectoralis, diaphragm and gastrocne mius muscles of rat were studied. 2. Cold acclimation resulted in mark ed morphological aberrations in the constituent muscle fibers coupled with metabolic changes recognized as early on as the first week. 3. Th e activities of all enzymes and total lipids witnessed an increase not ably in red and intermediate muscle fibers during prolonged acclimatio n. 4. A measurement of the cross sectional dimensions and populations of the different fiber types suggested an overall tendency among the t hree muscles to undergo a fiber transformation during cold acclimation . (C) 1997 Elsevier Science Ltd.