Figure 1.
Aging enhances ER-dependent [Ca2+]i increases in response to ACh. Fura-2 recordings of [Ca2+]i in response to 3 × 10–6 M ACh in the presence of 2 × 10–3 M [Ca2+]o (Control, “C”) and with 0 [Ca2+]o in A, Young and B, Old endothelium. C, Summary data for F340/F380 and D, ΔF340/F380 at designated time points (gray dots; refer to traces in A and B). Note initial peak of [Ca2+]i transients (reflecting Ca2+ release from ER) followed by sustained plateau (reflecting Ca2+ entry through the plasma membrane) during 90 s following peak response. Note diminished plateau during 0 [Ca2+]o to eliminate Ca2+ entry (A and B, right vs. left panels). Peak [Ca2+]i responses were similar across groups irrespective of [Ca2+]o (C and D). However, in Old endothelium, increases in [Ca2+]i remain elevated at 30 s and 60 s with 0 [Ca2+]o (D). *p < .05, old vs. young, n = 10 per group. ACh = acetylcholine; ER = endoplasmic reticulum.