[1] Univ Vermont, Coll Med, Dept Pharmacol, Burlington, VT 05405 USA
[2] Univ Colorado, Dept Anesthesiol, Anschutz Med Campus, Boulder, CO 80309 USA
[3] Univ Colorado, Dept Pharmacol, Anschutz Med Campus, Boulder, CO 80309 USA
[4] Univ Maryland, Sch Med, Dept Physiol, Baltimore, MD 21201 USA
[5] Michigan State Univ, Dept Pharmacol & Toxicol, E Lansing, MI 48824 USA
[6] Univ Manchester, Inst Cardiovasc Sci, Manchester, Lancs, England