FIGURE 4.

Inhibition of phospholipase C (PLC) blocks maresin 1 (MaR1)-stimulated increase in [Ca²⁺]_i. Goblet cells were incubated with the PLC inhibitor U73122 (10⁻⁷ M), its negative control U73143 (10⁻⁷ M, a and b) or (c and d) IP₃ receptor inhibitor 2-APB (10⁻⁵ M) for 30 min and stimulated with MaR1 at 10⁻⁸ M for [Ca²⁺]_i or 10⁻⁹ M for secretion or carbachol (Cch, 10⁻⁴ M). (a) and (c) show the change in peak [Ca²⁺]_i while (b) and (d) show high molecular weight glycoprotein secretion. (e) Rat conjunctival goblet cells were preincubated with the SERCA-inhibitor thapsigargin (10⁻⁵ M) for 15 min and stimulated with either MaR1 (10⁻⁸ M) or carbachol (Cch, 10⁻⁴ M). (f) Goblet cells were incubated with KRB with or without CaCl₂ and stimulated with MaR1 (10⁻⁸ M) or Cch (10⁻⁴ M). (e and f) The change in peak [Ca²⁺]_i. Data are mean ± SEM of three (a–e) or five (f) experiments. *Significance above basal. #Significant difference from MaR1 or Cch alone. 2-APB, 2-aminoethoxydiphenyl borate; [Ca²⁺]_i, intracellular Ca²⁺; KRB, Krebs–Ringer bicarbonate buffer; SEM, standard error of the mean; SERCA, sarco/endoplasmic reticulum