Table 2. Demographic characteristics, resting physiological values of Tibetan and Han groups living at SL and HA for more than one year.

Variables§		SL (400 m)				HA (3658 m)
		Han-SL		Tibetan-SL		Han-HA		Tibetan-HA
Demographics		Female	Male	Female	Male	Female	Male	Female	Male
Sample size, n		24	24	26	20	42	60	37	38
Age, years		21 ± 1	21 ± 1	21 ± 1	21 ± 1	22 ± 2	21 ± 3	21 ± 1†	21 ± 3
Height, cm		161 ± 4	172 ± 5#	161 ± 4	172 ± 5#	162 ± 6	172 ± 6#	161 ± 6	170 ± 6#
Weight, kg		53 ± 7	63 ± 7#	51 ± 4	62 ± 7#	53 ± 7	61 ± 7#	52 ± 6	60 ± 8#
BMI, kg/m2		20.3 ± 2.3	21.3 ± 2.3	19.8 ± 1.9	20.8 ± 2.1	20.2 ± 2.1	20.8 ± 1.8	20.2 ± 1.7	20.6 ± 2.4
BSA, m2		1.54 ± 0.11	1.74 ± 0.11#	1.52 ± 0.07	1.72 ± 0.11#	1.54 ± 0.12	1.71 ± 0.10#	1.53 ± 0.10	1.68 ± 0.12#
Systemic measurements
SBP, mmHg		107 ± 6	117 ± 8#	114 ± 9†	123 ± 11#†	117 ± 10*	125 ± 10#*	112 ± 9†	121 ± 10#
DBP, mmHg		66 ± 6	66 ± 5	67 ± 6	67 ± 7	74 ± 10*	74 ± 9*	68 ± 7†	69 ± 10†
MAP, mmHg		80 ± 5	83 ± 6	83 ± 7	86 ± 8	88 ± 9*	91 ± 9*	83 ± 7†	87 ± 9#†
Heart rate, beats/min		69 ± 10	66 ± 8	72 ± 11	69 ± 12	77 ± 13*	70 ± 12#	70 ± 7†	70 ± 11
Hct, %		39.9 ± 3.2	45.7 ± 2.9#	34.9 ± 3.5†	40.3 ± 4.4#†	46.1 ± 3.6*	51.6 ± 2.8#*	42.0 ± 4.7*†	47.8 ± 3.6#*†
Hb, gm/dL		13.5 ± 1.3	15.9 ± 1.1#	11.2 ± 1.3†	13.2 ± 1.5#†	16.0 ± 1.4*	18.6 ± 1.0#*	14.4 ± 1.8*†	16.8 ± 1.3#*†
SaO2, %		98.2 ± 0.9	98.0 ± 0.6	97.9 ± 0.5	97.9 ± 0.4	92.7 ± 2.5*	92.0 ± 1.7*	92.7 ± 2.1*	92.1 ± 2.1*
CaO2, ml O2/dL		18.0 ± 1.8	21.2 ± 1.4#	14.9 ± 1.7†	17.6 ± 2.0#†	20.2 ± 1.6*	23.2 ± 1.3#*	18.2 ± 2.2*†	21.0 ± 1.5#*†
ICA measurements
Diameter, mm	R	4.24 ± 0.39	4.53 ± 0.30#	4.27 ± 0.40	4.55 ± 0.30#	4.72 ± 0.42*	4.95 ± 0.47#*	4.41 ± 0.51†	4.60 ± 0.44†
	L	4.19 ± 0.32	4.48 ± 0.22#	4.32 ± 0.33	4.51 ± 0.34	4.60 ± 0.39*	4.85 ± 0.51#*	4.36 ± 0.49†	4.63 ± 0.47#†
CBFV, cm/s	R	26.6 ± 7.1	24.0 ± 3.6	27.7 ± 4.6	27.6 ± 4.4†	22.7 ± 4.6*	20.5 ± 3.8#*	23.4 ± 5.4*	20.8 ± 5.4#*
	L	29.6 ± 5.5	25.0 ± 4.5#	29.1 ± 3.5	25.8 ± 4.3#	22.9 ± 4.4*	21.0 ± 3.7#*	21.8 ± 6.8*	19.9 ± 5.1*
CBF, mL/min	R	223 ± 51	233 ± 43	238 ± 50	270 ± 51#†	236 ± 46	236 ± 53	215 ± 65	207 ± 62*†
	L	242 ± 40	236 ± 43	255 ± 42	249 ± 56	227 ± 48	233 ± 57	194 ± 59*†	201 ± 58*†
VA measurements
Diameter, mm	R	3.00 ± 0.53	3.13 ± 0.41	2.97 ± 0.47	3.06 ± 0.41	3.30 ± 0.46*	3.35 ± 0.37*	3.11 ± 0.39†	3.27 ± 0.52
	L	3.14 ± 0.44	3.21 ± 0.38	3.07 ± 0.41	3.12 ± 0.42	3.43 ± 0.42*	3.51 ± 0.42*	3.27 ± 0.33*	3.34 ± 0.56
CBFV, cm/s	R	18.7 ± 3.7	16.1 ± 3.2#	20.2 ± 3.8	17.9 ± 3.7#	14.9 ± 2.6*	13.7 ± 2.8#*	14.7 ± 3.9*	13.4 ± 3.2*
	L	19.3 ± 4.9	17.3 ± 3.1	18.7 ± 3.3	16.0 ± 2.9#	16.4 ± 3.1*	15.1 ± 2.7#*	15.6 ± 3.5*	14.1 ± 2.7#*
CBF, mL/min	R	81 ± 29	77 ± 29	88 ± 37	82 ± 30	79 ± 26	74 ± 24	69 ± 26*	71 ± 30
	L	93 ± 38	86 ± 28	86 ± 30	77 ± 33	93 ± 32	89 ± 27	79 ± 21†	78 ± 31
Global brain perfusion
TCBF, mL/min		639 ± 84	632 ± 89	668 ± 92	677 ± 112	635 ± 92	631 ± 109	556 ± 105*†	557 ± 121*†
TCVR, 10−3 mmHg∙min/mL		127 ± 19	134 ± 22	126 ± 20	132 ± 38	143 ± 29*	149 ± 30*	154 ± 34*	162 ± 35*
TCOD, mL O2/min		115 ± 20	134 ± 20#	100 ± 17†	119 ± 23#†	128 ± 23*	146 ± 24#*	101 ± 20†	116 ± 24#†
CBF distribution
QVA/TCBF, %		27.3 ± 5.8	25.8 ± 3.7	26.1 ± 5.0	23.3 ± 3.4#†	27.1 ± 4.6	26.1 ± 4.1	27.3 ± 6.4	27.2 ± 5.4*

^§Values are mean ± SD.

^#P < 0.05 vs. females,

^†P < 0.05 vs. Han group, and

^*P < 0.05 vs. the SL counterpart, using un-paired t test. SL = sea level; HA = high altitude; Han-SL = Han natives at SL; Tibetan-SL = Tibetan migrants staying at SL for 2 years; Han-HA = Han migrants at HA for 1 or 5 years; Tibetan-HA = Tibetan natives at HA; BMI = body mass index; BSA = body surface area =  ; SBP = systolic blood pressure; DBP = diastolic blood pressure; MAP = mean arterial pressure; Hct = hematocrit; Hb = hemoglobin concentration; SaO₂ = arterial blood oxygen saturation; CaO₂ = arterial oxygen content; ICA = internal carotid artery; CBFV = cerebral blood flow velocity, i.e. the space- and time-averaged mean velocity; CBF = cerebral blood flow; VA = vertebral artery; TCBF = total CBF; TCVR = total cerebrovascular resistance; TCOD = total cerebral oxygen delivery; Q_VA/TCBF = the percentage of bilateral VA CBFs to TCBF.