1. From the Microvascular Research Laboratories, Bristol Heart Institute, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Bristol, United Kingdom;
2. University Eye Hospital, Albert-Ludwig University, Freiburg, Germany;
3. Division of Nephrology and Clinical Immunology, University Hospital, RWTH University of Aachen, Achen, Germany; and
4. Unit of Ophthalmology, University of Bristol, Bristol Eye Hospital, Bristol, United Kingdom.