Figure 3.

Time-dependent effects of culture with (a,b) BTS 67 582 or (c) tolbutamide on subsequent insulin-secretory responsiveness to (a,c) BTS 67 582 and (b) tolbutamide. After 3, 6, 12 or 18 h culture in the absence (standard culture conditions) or presence of either 100 μM BTS 67 582 (BTS culture) or 100 μM tolbutamide (Tol culture), cells were preincubated for 40 min before 20 min acute incubation with a buffer containing 1.1 mM glucose in the absence or presence of either 200 μM BTS 67 582 (BTS) or 200 μM tolbutamide (Tol). Values are mean±s.e.mean for six separate observations. Insulin-secretory responses to control (1.1 mM glucose) remained constant from 3–18 h regardless of culture condition employed (in ng per 10⁶ cells 20 min⁻¹: 1.90±0.11 for standard culture conditions; 1.97±0.12 for BTS culture; 1.88±0.09 for Tol culture). ^*P<0.05, ^**P<0.01, ^***P<0.001 compared with respective effects of control (1.1 mM glucose alone). ΔΔΔP<0.001 compared with respective effects after standard culture conditions.