Lee T F, Wang L C
Life Sci. 1985 May 27;36(21):2025-32. doi: 10.1016/0024-3205(85)90452-7.
During severe cold exposure, old rats (23-26 months) were less capable in maintaining normal body temperature as compared to young rats (6-9 months) due to lower rate of heat production (HP). Single injection of optimal doses of aminophylline (AMPY; 10 and 18.7 mg/kg, i.p.), a phosphodiesterase inhibitor which enhances the intracellular cyclic AMP concentration, significantly increased the rate of HP in old rats to levels beyond the control values observed in young rats. Consequently, cold tolerance of the old rats was significantly improved. This AMPY-improved cold tolerance is apparently not due to increased non-shivering thermogenesis (NST) since AMPY failed to enhance norepinephrine-stimulated NST in the old rats. It is likely that AMPY increased substrate mobilization and/or conversion, thereby circumventing the limiting role of substrate availability for shivering thermogenesis. Thus, the age-dependent decrease in cold tolerance may be due to a reduced capacity for substrate mobilization when challenged by cold.
在严重冷暴露期间，与年轻大鼠（6 - 9个月）相比，老年大鼠（23 - 26个月）由于产热（HP）速率较低，维持正常体温的能力较差。单次注射最佳剂量的氨茶碱（AMPY；10和18.7毫克/千克，腹腔注射），一种可提高细胞内环磷酸腺苷浓度的磷酸二酯酶抑制剂，可显著提高老年大鼠的HP速率，使其超过年轻大鼠的对照值水平。因此，老年大鼠的耐寒性显著提高。AMPY改善的耐寒性显然不是由于非颤抖性产热（NST）增加，因为AMPY未能增强老年大鼠中去甲肾上腺素刺激的NST。AMPY可能增加了底物的动员和/或转化，从而规避了底物可用性对颤抖性产热的限制作用。因此，耐寒性的年龄依赖性下降可能是由于受到寒冷挑战时底物动员能力降低所致。
