Chiappe de Cingolani G E
Cátedra de Fisiología con Biofísica, Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Argentina.
Mol Cell Biochem. 1992 Sep 22;115(1):97-103. doi: 10.1007/BF00229101.
The effects of isoproterenol and insulin on phospholipid methyltransferase (PLMT) activity were investigated in adipocytes from control and streptozotocin-diabetic rats. PLMT activity was assayed by measuring the rate of incorporation of 3H-methyl groups from S-adenosyl-L-[methyl-3H] methionine into phospholipids. Basal PLMT activity was higher in adipocytes from diabetic animals. Treatment of adipocytes with isoproterenol induced a concentration-dependent stimulation of PLMT activity. In control adipocytes, the maximal effect was obtained at 100 nM isoproterenol with 2.3 fold increase in PLMT activity and a half maximal effect at 25 nM. In adipocytes from diabetic rats, a lower dose of isoproterenol (10 nM), caused 1.2 fold increase with a half maximal effect at 4 nM. Addition of 100 nM insulin inhibited basal PLMT activity and the stimulatory effect of isoproterenol in both types of adipocytes. The beta-adrenergic blocking agent propranolol inhibited the stimulatory effect of isoproterenol on PLMT activity in control and diabetic adipocytes. Intracellular concentration of cAMP was higher in diabetic adipocytes but decreased to normal values after incubation in the presence of insulin.
研究了异丙肾上腺素和胰岛素对正常大鼠及链脲佐菌素诱导的糖尿病大鼠脂肪细胞中磷脂甲基转移酶（PLMT）活性的影响。通过测量S-腺苷-L-[甲基-³H]甲硫氨酸中³H-甲基基团掺入磷脂的速率来测定PLMT活性。糖尿病动物脂肪细胞的基础PLMT活性较高。用异丙肾上腺素处理脂肪细胞可诱导PLMT活性呈浓度依赖性刺激。在正常脂肪细胞中，100 nM异丙肾上腺素时达到最大效应，PLMT活性增加2.3倍，25 nM时达到半数最大效应。在糖尿病大鼠的脂肪细胞中，较低剂量的异丙肾上腺素（10 nM）可使PLMT活性增加1.2倍，4 nM时达到半数最大效应。添加100 nM胰岛素可抑制两种类型脂肪细胞的基础PLMT活性以及异丙肾上腺素的刺激作用。β-肾上腺素能阻滞剂普萘洛尔可抑制异丙肾上腺素对正常和糖尿病脂肪细胞中PLMT活性的刺激作用。糖尿病脂肪细胞中的细胞内cAMP浓度较高，但在胰岛素存在下孵育后降至正常值。
