Figure 6.

Pharmacological depletion of intracellular Ca²⁺ stores restores nifedipine (Nif) sensitivity to depolarization-induced contractions in rat MV. Blocking store-operated Ca²⁺ release with Gd³⁺ (A, 100 µmol/L) or La³⁺ (B, 100 µmol/L) did not reduce venous KCl-induced constriction or restore sensitivity to Nif in veins. (n = 4–5) (C) KCl-induced constrictions after Thaps were blocked 80% by Nif (10 µmol/L). (n = 6) (D) Store depletion by caffeine (Caf, 10 mmol/L) also resulted in sensitivity to block by Nif. (E) Using ryanodine (Ryan, 10 nmol/L) to deplete intracellular Ca²⁺ stores also resulted in MV sensitivity to nifedipine, (n = 5–6), as did incubating with 2-APB (100 µmol/L) (F) (n = 6). * = significant difference from Control (Con), p<0.05; † = significant difference between Thaps, Caf, Ryan, or 2-APB in the presence and absence of Nif.