Clinical measurements included whole-body norepinephrine kinetics -LSB- spillover rate , plasma clearance , and the steady state ratio of tritiated @,@-dihydroxyphenylglycol to tritiated norepinephrine ( -LSB- ( @ ) H -RSB- - DHPG to -LSB- ( @ ) H -RSB- - NE ) as an index of neuronal uptake-@ -RSB- , muscle sympathetic nerve activity , spontaneous baroreflex sensitivity , euglycemic hyperinsulinemic clamp , oral glucose tolerance test , ambulatory blood pressure , and Doppler echocardiography .