Figure 4.

Time-dependent recovery of insulin-secretory responsiveness to (a,c) BTS 67 582 or (b) tolbutamide after 18 h culture with (a,b) 100 μM BTS 67 582 or (c) tolbutamide. After 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 cultured in the absence of BTS 67 582 or tolbutamide for 0, 12 or 18 h before preincubation (40 min) and subsequent 20 min incubation with a buffer containing 1.1 mM glucose in the absence or presence of 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: 1.92±0.08 for standard culture conditions; 2.00±0.08 for BTS culture; 1.96±0.11 for Tol culture). ^*P<0.05, ^***P<0.001 compared with respective effects of control (1.1 mM glucose). ΔΔΔP<0.001 compared with respective effects after standard culture conditions. †††P<0.001 compared with respective effects at 0 h.