Fig. 5.

Effect of CaSR expression on stimulated secretion of CCK from isolated I cells. CCK secretion was from sorted CaSR^+/+ (solid bars; A) and CaSR^−/− (open bars; B) CCK-eGFP cells in response to a 30-min incubation with l-Phe (30 mM) alone and with additional extracellular Ca²⁺ (2.5 mM), 2.5 mM Ca²⁺ alone, d-Phe (30 mM), 1% tryptone, and KCl (50 mM). CCK secreted in the supernatant was measured by RIA. Results are presented as %change (means ± SE) from baseline CCK secretion in Hank's balanced salt solution supplemented with 10 mM HEPES (HHBSS) alone. N = 6–9 separate cell preparations for all treatments, with each condition performed and sampled in triplicate. *P < 0.05 and **P < 0.01, relative to baseline secretion within each genotype.