Table 2.

Responses to limb dependency (Protocol 1)

	Arm		Leg
Limb position	Heart level	Limb dependent	Heart level	Limb dependent
Young (n=12)
HR, beats/min	61±2	61±2	63±2	61±2*
Mean BP, mmHg	85±1	85±2	84±1	85±1
Mean BP (corrected)	85±1	108±2	84±1	108±1
Limb MBV, cm/sec	1.7±0.2	1.4±0.2*	1.3±0.1	0.9±0.1*
Δ Limb MBV, cm/sec	--	−0.3±0.1*	--	−0.4±0.1*
Limb VR index, au	61±10	95±15*	72±8	142±15*
Δ Limb VR index, au	--	34±6*	--	70±9*‡
Skin flux, au	30.1±3.9	14.1±2.8*	25.7±3.8	10.0±1.9*
Δ Skin flux, au	--	−16.0±1.8*	--	−15.7±2.3*
Skin VR index, au	3.3±0.5	11.0±1.9*	4.5±1.0	14.7±2.1*
Δ Skin VR index, au	--	7.7±1.5*	--	10.2±1.6*
Older (n=12)
HR, beats/min	60±2	59±2	58±2†	58±2†
Mean BP, mmHg	89±1†	90±2†	92±1†	93±2†
Mean BP (corrected)	89±1†	123±2†	92±1†	116±2†
Limb MBV, cm/sec	1.7±0.2	1.4±0.1*	1.2±0.10	0.9±0.1*
Δ Limb MBV, cm/sec	--	−0.3±0.1*	--	−0.3±0.1*†
Limb VR index, au	57±5	91±10*	86±9	136±13*
Δ Limb VR index, au	--	34±7*	--	50±6*†
Skin flux, au	25.8±4.7	11.9±2.8*	18.4±2.6†	6.9±0.7*
Δ Skin flux, au	--	−13.9±2.8*	--	−11.5±2.3*
Skin VR index, au	4.9±0.9	14.2±2.6*	6.1±0.7	18.4±1.7*
Δ Skin VR index, au	--	9.2±2.1*	--	12.3±1.2*

Values are mean±SE; HR=heart rate; BP=arterial pressure; MBV=mean blood velocity; VR=vascular resistance index (mean BP/MBV or flux);

Mean BP (corrected) accounts for hydrostatic pressure effects (mean BP+(0.766^*30cm)) when the limb was dependent (i.e., lowered below heart level).

Limb responses were measured in the brachial (arm) and popliteal artery (leg). Skin responses were measured on the ventral aspect of the forearm (arm) and calf (leg).

^*P<0.05 Δ from heart level

^†P<0.05 compared to young (same time point)

^‡compared to response in arm (same age group)