1. Departments of Physiology (R.L.B., S.S., T.V.M., P.P.B.), School of Medical Sciences, University of New South Wales, Sydney NSW 2052 Australia
2. Pharmacology (S.S., I.M., L.L., L.H, H.C., S.L.S.), School of Medical Sciences, University of New South Wales, Sydney NSW 2052 Australia