You seem to enjoy learning Maffin!
Maybe these will help
http://www.pspinformation.com/disease/otherdiseases/hypotension.shtml
http://www.cybermedicine2000.com/pharmacology2000/Autonomics/Adrenergics1/Adrenergic-53.htm
http://nursingpharmacology.info/Autonomics/Adrenergics/Adren1.htm