Chou H F, Ipp E
Department of Medicine, Harbor-UCLA Medical Center, Torrance 90509.
Diabetes. 1990 Jan;39(1):112-7. doi: 10.2337/diacare.39.1.112.
The pancreas secretes insulin in an oscillatory fashion, but the precise site of the pacemaker for pulsatile insulin secretion has not been identified. These studies were designed to determine whether islets also secrete insulin in a pulsatile fashion if they are isolated from their pancreatic milieu. Isolated rat islets (80-100) were perifused 8 h in culture medium after overnight incubation, and samples were collected at 3.3-min intervals. Insulin secretion was evaluated for pulsatility with the Clifton Cycle Detection Program. Perifusion of islets was associated with a spontaneous, persistent, and regular pulsatility of insulin secretion, which was observed in all conditions tested. Perifusion with medium containing 5.5 mM glucose (n = 11) demonstrated oscillations with a mean periodicity of 17.6 +/- 1.1 min and a mean amplitude of 4.8 +/- 0.4 microU/ml when overall mean insulin concentration was 16.7 +/- 2.4 microU/ml. When the glucose concentration was 16.7 mM (n = 9), overall mean insulin concentration was 54.4 +/- 2.6 microU/ml, with increases in periodicity (22.0 +/- 1.3 min) and amplitude (10.7 +/- 0.5 microU/ml). All measurements were significantly different from those observed during perifusion with 5.5 mM glucose (P less than 0.02-0.001). Theophylline (1 mM) also enhanced the overall mean insulin concentration and amplitude (69.4 +/- 10.4 and 14.2 +/- 1.2 microU/ml, respectively) compared with control studies without theophylline (16.7 +/- 5.3 and 4.3 +/- 0.5 microU/ml) (P less than 0.01). The period of the cycle was also increased from 17.5 +/- 1.1 to 26.4 +/- 6.3 min, but this was not significantly different from the control group.(ABSTRACT TRUNCATED AT 250 WORDS)
胰腺以振荡方式分泌胰岛素，但尚未确定脉冲式胰岛素分泌的起搏器的确切位置。这些研究旨在确定胰岛如果从胰腺环境中分离出来是否也以脉冲方式分泌胰岛素。将分离的大鼠胰岛（80 - 100个）过夜培养后在培养基中灌注8小时，每隔3.3分钟收集样本。使用克利夫顿周期检测程序评估胰岛素分泌的脉冲性。胰岛的灌注与胰岛素分泌的自发、持续且规律的脉冲性相关，在所有测试条件下均观察到这种情况。用含5.5 mM葡萄糖的培养基灌注（n = 11）时，当总体平均胰岛素浓度为16.7 +/- 2.4微单位/毫升时，显示出振荡，平均周期为17.6 +/- 1.1分钟，平均振幅为4.8 +/- 0.4微单位/毫升。当葡萄糖浓度为16.7 mM（n = 9）时，总体平均胰岛素浓度为54.4 +/- 2.6微单位/毫升，周期（22.0 +/- 1.3分钟）和振幅（10.7 +/- 0.5微单位/毫升）增加。所有测量值与用5.5 mM葡萄糖灌注时观察到的测量值均有显著差异（P小于0.02 - 0.001）。与不含茶碱的对照研究（16.7 +/- 5.3和4.3 +/- 0.5微单位/毫升）相比，茶碱（1 mM）也提高了总体平均胰岛素浓度和振幅（分别为69.4 +/- 10.4和14.2 +/- 1.2微单位/毫升）（P小于0.01）。周期也从17.5 +/- 1.1分钟增加到26.4 +/- 6.3分钟，但与对照组无显著差异。（摘要截短至250字）
