A, representative graph of force versus frequency relationship. B, acute effect of 1 mm RGD peptide on the active force generated by papillary muscle from the right ventricle of a mouse heart. A significant inhibition of force is observed. C, effect of varying concentrations of RGD on force development. Note that 1 mm GRGDNP peptide causes maximal inhibition of force development. The 100% value of force/cross-sectional area represents the control measurement prior to addition of the RGD peptide. Data are presented as mean ± s.e.m., *P < 0.05, paired t test.