Polyamines regulate calcium fluxes in a rapid plasma membrane response

Activation of cell-surface receptors often evokes changes in Ca 2+ fluxes leading to an increase in cytosolic Ca 2+ , a generally accepted mediator of many cell responses 1–3 . The molecular mechanisms by which surface agonists elicit these changes in Ca 2+ flux have remained elusive. An increase in the polyamines putrescine, spermidine and spermine, and their rate-regulating, synthetic enzyme ornithine decarboxylase (ODC), is one of the earliest events that occur during cell growth, replication and differentiation 4–6 . However, the precise physiological roles of the polyamines remain enigmatic 4–6 . Recently, we found that testosterone induces an early (