Figure 6
Expression of the bombesin/GRP receptor in Rat-1 fibroblasts increases sensitivity to growth inhibition by SP-G. Rat-1a fibroblasts (A) or rat-1a fibroblasts expressing the bombesin receptor (B) were loaded with FURA-2-AME and resuspended in electrolyte solution. Fluorescence was monitored and basal and peak [Ca2+]i calculated as described in Materials and Methods. (A) Rat-1a cells were stimulated with 10 nM each of bombesin (Bn), vasopressin (Vp), neurotensin (NT) and bradykinin (Bk), 10 μ M SP-G or 1% FCS. The results are representative of three experiments. (B) (left) Response to 10 nM bombesin in BOR-15 cells and (right) effect of 10 μ M SP-G on bombesin-stimulated Ca2+ release in BOR-15 cells. (C) Rat-1 fibroblasts (closed squares) or Rat-1 fibroblasts expressing the bombesin receptor (BOR15, open squares) were grown in SITA media in the presence or absence of the indicated concentrations of SP-G. The cell number was determined and IC50 values calculated following 7 days of growth.
