Figure 1.

Serenase, a commercial preparation of haloperidol, stimulates Ca²⁺ release from isolated rabbit skeletal muscle terminal cisternae. The experiments were carried out as described in the Methods section, using the Ca²⁺ indicator antipyrylazo-III. Where indicated six consecutive additions of 25 nmol of CaCl₂ were administered; after Ca²⁺ loading, 150 μl Serenase (1 : 10 dilution) were added. At the end of the experiment the Ca²⁺ ionophore A23187 was added to release remaining Ca²⁺, followed by the addition of 25 nmol CaCl₂ used to calibrate the dye response. Upward deflections indicate Ca²⁺ release and downward deflections indicate Ca²⁺ accumulation.