RESUMO
Objective To study the signal transduction pathway for myocyte contraction induced by Substance K (SK) in rats. Methods The fluorescent Ca 2+ indicator Fluo 3AM was used to quantitate the calcium signal directly in the primary cultured myocardial cells. Changes of free Ca 2+ concentration in cardiac myocytes were detected by flow cytometry. The phospholipase C (PLC) inhibitor, neomycin and IP3 receptor antagonist, heparin, were used to block signal system of phosphates Ca 2+ in order to investigate whether they took part in the SK induced changes of [Ca 2+ ]i in myocytes. Results SK(1.78?10 -5 mol/L) elevated [Ca 2+ ]i in myocytes. The effects could be blocked by neomycin and heparin. Conclusion SK can elevate [Ca 2+ ]i in myocyte, which may be mediated by a signal system of phosphates Ca 2+ .