The rise in clearing-factor lipase activity that occurs when epididymal fat bodies from starved rats are incubated in appropriate media in vitro is inhibited in the presence of 6-N-2'-O-dibutyryl-3',5'-(cyclic)-AMP (1mm). 2. Inhibition occurs at a concentration of glucose in the incubation medium of 1.3mg./ml. or less, but not at a glucose concentration of 2.4mg./ml., unless caffeine (1mm), an inhibitor of 3',5'-(cyclic)-nucleotide phosphodiesterase, is also present. Caffeine (5mm) alone inhibits the rise in clearing-factor lipase activity at a glucose concentration of 2.4mg./ml. of medium. 3. The concentration of free fatty acids in the epididymal fat bodies normally falls during incubations in vitro as the rise in clearing-factor lipase activity occurs. In the presence of 1mm-6-N-2'-O-dibutyryl-3',5'-(cyclic)-AMP, however, either the tissue free fatty acid concentration is increased or it does not fall to the same extent. The concentration of glucose in the incubation medium is important in determining the direction and extent of the changes in tissue free fatty acid concentration that occur in the presence of 6-N-2'-O-dibutyryl-3',5'-(cyclic)-AMP. 4. Free fatty acid concentrations in epididymal fat bodies in vivo rise as the clearing-factor lipase activity of the tissue falls during starvation. 5. The possibility that the concentration of 3',5'-(cyclic)-AMP in adipose tissue may regulate clearing-factor lipase activity, and that the regulation may occur through effects of the nucleotide on tissue free fatty acid concentrations, is discussed.
摘要
当将饥饿大鼠的附睾脂肪体在合适的培养基中进行体外孵育时，所出现的清除因子脂肪酶活性的升高，在存在6 - N - 2'- O - 二丁酰 - 3',5' -（环）- 腺苷酸（1毫摩尔）的情况下受到抑制。2. 在孵育培养基中葡萄糖浓度为1.3毫克/毫升或更低时会出现抑制现象，但在葡萄糖浓度为2.4毫克/毫升时则不会，除非同时存在3',5' -（环）- 核苷酸磷酸二酯酶的抑制剂咖啡因（1毫摩尔）。单独的咖啡因（5毫摩尔）在培养基葡萄糖浓度为2.4毫克/毫升时会抑制清除因子脂肪酶活性的升高。3. 在体外孵育过程中，随着清除因子脂肪酶活性升高，附睾脂肪体中游离脂肪酸的浓度通常会下降。然而，在存在1毫摩尔6 - N - 2'- O - 二丁酰 - 3',5' -（环）- 腺苷酸的情况下，要么组织游离脂肪酸浓度升高，要么其下降幅度没有那么大。孵育培养基中葡萄糖的浓度对于确定在存在6 - N - 2'- O - 二丁酰 - 3',5' -（环）- 腺苷酸时组织游离脂肪酸浓度变化的方向和程度很重要。4. 在饥饿期间，随着组织的清除因子脂肪酶活性下降，附睾脂肪体中游离脂肪酸的浓度在体内会升高。5. 讨论了脂肪组织中3',5' -（环）- 腺苷酸的浓度可能调节清除因子脂肪酶活性，并且这种调节可能通过该核苷酸对组织游离脂肪酸浓度的影响而发生的可能性。
