Potassium Current Is Not Affected by Long-Term Exposure to Ghrelin or GHRP-6 in Somatotropes GC Cells
Figure 12
Effect of GHRP-6 on the K+ inward-rectifier current (KIR) in the cellular line of rat GC somatotropes. (a) Recording protocol to evoke the inward-rectifier current in GC cells, taken from Xu et al. [15], The protocol consists of hyperpolarizing pulses from −160 to −40, starting from a holding potential of −50 mV and a duration of 250 ms in steps of 10 mV, with the same recording solution for the K+ current. (b) Family of KIR current traces showing two components, an initial (transient) one of rapid activation and inactivation in the first 2-3 ms, followed by a (sustained) component of slow activation that remains for the 250 ms duration of the pulse. The transient component was measured 1 ms after the end of the capacitive component to avoid contamination from the component, the latter having a duration of ~0.3 ms; the sustained component was measured 5 ms before the end of the current trace (245–250 ms). (c) Insert of the same trace shown in (b), which was expanded in time so as to observe the transient component of the KIR current. (d) Current-voltage curves of the two KIR components. (e) and (f): current and density of current measured in the trace at −160 mV. The capacitance value for the control cells was and for the cells treated with GHRP-6 it was ; the numbers beside the error bars show the number of cells analyzed.
