Imperatoxin A (IpTxa) is a 33 amino acid peptide toxin from the African scorpion Pandinus imperator. Its definitive structural and functional characteristics designate it as a member of the calcin family, a unique group of peptide toxins, which to date includes Hemicalcin (HCa), Hadrucalcin (HdCa), IpTxa, Maurocalcin (MCa), and Opicalcins 1 & 2 (Opi 1 & 2). Calcins are unified by 1) a compact, globular structure containing an inhibitor cystine knot, 2) positive net charge, 3) the ability to activate ryanodine receptors (RyR) with high affinity and selectivity, and 4) presumed or confirmed cell-penetrating capabilities. Previous studies have demonstrated the ability of MCa to carry a fluorescent cargo to the interior of intact cells, and we have used a similar method to confirm that IpTxa is also a cell-penetrator. In addition, we have demonstrated IpTxa's ability to transiently enhance calcium release from the sarcoplasmic reticulum (SR) of intact cells. In the current study, we used confocal microscopy to explore the effects of IpTxa on saponin-permeabilized cells. Perfusion of 10nM IpTxa on cells resulted in a dramatic reduction of sparks to as low as 1% of control within two minutes. This effect was even more pronounced and rapid in the presence of 50nM toxin, with complete ablation of sparks in less than 1 minute. At the same time, mean fluorescence is often increased in our scans relative to control, although rapid application of caffeine reveals that SR calcium content is retained. Our results suggest that IpTxa depletes calcium from the SR, a hypothesis that would explain not only the ablation of sparks, but also the transient nature of enhanced calcium release in intact cells observed upon perfusion with IpTxa.