Figure 3.

Increases in [Ca²⁺]_i elicited by NPS R-568 are refractory to inhibition by La³⁺ but are blocked by removal of extracellular Ca²⁺. Bovine parathyroid cells were suspended in medium containing 0.5 mM CaCl₂. In all traces, the final concentration of NPS R-568 was 1 μM. La³⁺ (1 μM, final), EGTA (1 mM, final), or Mg²⁺ (3 mM, final) was added as indicated. The numbers accompanying each trace are estimates of [Ca²⁺]_i in nM. Each trace is from a single preparation of cells and is representative of the pattern seen in three other experiments.