1. From the Laboratory for Physiology (J.v.d.V., B.R.K., A.T.J., N.M.B., G.J.M.S.), Institute for Cardiovascular Research, VU University Medical Center, Amsterdam; Experimental Cardiology, Thoraxcenter (D.M., D.J.D.) and Department of Biochemistry (D.H.W.D., J.M.J.L.), Cardiovascular Research School Cardiovasculaire Onderzoekschool Erasmus Universiteit Rotterdam, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, the Netherlands.