- In vitro and in vivo characterization of intrinsic sympathomimetic activity in normal and heart failure rats. Willette, R.N., Aiyar, N., Yue, T.L., Mitchell, M.P., Disa, J., Storer, B.L., Naselsky, D.P., Stadel, J.M., Ohlstein, E.H., Ruffolo, R.R. J. Pharmacol. Exp. Ther. (1999)