title: Ambiguous response of lung lamellar bodies to sauna-like heat stress in two age groups of adult male rats.
abstract: Two groups of adult male rats, aged 2.5 and 5 months, were exposed daily for 12 min to 65 degrees C for five successive periods a week for 6 weeks. Both age groups, and in particular the young one, repeatedly suffered from exhausting heat stress. Lung specimens from cardiac lobes were prepared for light- and electron-microscopy. A significnat increase was noted in the lung lamellar body number in the old test rats, on comparison with old ones employed as controls (p < 0.05). The young group was unresponsive. Consequently, stress induced by increased sympathetic activity is not always a direct stimulus, as had been thought earlier. It seems, at least where heat stress is concerned, that it is the age, weight, and systemic reactions which exercise a great influence upon lamellar body production, and may even overrule the role of sympathetic activity.
mesh_terms: D000367:Age Factors; D000818:Animals; D001835:Body Weight; D006358:Hot Temperature / Q000009:adverse effects*; D008297:Male; D011650:Pulmonary Alveoli / Q000503:physiopathology*; D051381:Rats; D013312:Stress, Physiological / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000503:physiopathology