Potassium Current Is Not Affected by Long-Term Exposure to Ghrelin or GHRP-6 in Somatotropes GC Cells
Figure 6
Effect of chronic treatment with secretagogues (ghrelin or GHRP-6) on the percentage of the components of the voltage-dependent potassium current on the cellular line of rat GC somatotropes. (a) Representative traces of a control cell. The current was evoked upon passing from a holding potential from −80 mV to −130 mV for 500 ms, from there to depolarize the cell at 60 mV for 1.5 seconds in order to obtain the totality of K+ current. Subsequently, an extracellular solution supplemented with specific blockers for the (tetraethylammonium; TEA 30 mM) and currents (4-aminopyridine; 4-AP 5 mM) was perfused with the aim of desiccating the components of the K+ current. It should be noted that, before a blocker was used, the control solution was employed for washing the effect of the blocker. (b) Summary of the results obtained by using blockers in the control cells () and in the cells treated chronically with GHRP-6 100 mM (). The measurements were made at the peak in the first 50 ms, and in the sustained component of the trace in the last 5 ms. The peak and sustained values of the current in the control cells were and pA, respectively, and for the cells treated chronically with GHRP-6 (100 mM), they were and pA, respectively.
