Figure 1.
GLP-1 potentiates exocytosis in B-cells. Increases in cell capacitance (ΔCm, bottom trace) elicited by progressively longer (5, 10, 15, 30, 50, 100, 150, 250, 350, 450, and 850 ms) depolarizations from −70 to 0 mV (V, top trace) under (A) control conditions and (B) 4 min after the inclusion of 10 nM GLP-1 in the extracellular medium. The interval between two successive depolarizations was 15 s for pulses ≤50 ms and 30 s for longer pulses. For clarity, only responses to the 30-, 100-, 250-, and 450-ms depolarizations are shown. The recording was performed using the perforated patch configuration. (C) Relationship between pulse duration (t) and increase in cell capacitance (ΔCm) under control conditions and in the presence of 10 nM GLP-1 as indicated. The curves were derived by fitting Eq. 3 to the data points for depolarizations ≤350 ms. The dotted lines represent linear fits to the values measured in response to the two longest depolarizations. Data are mean values ± SEM of seven paired experiments. *P < 0.05 and **P < 0.01.