Local heat stress and skin blood flowmotion in subjects with familial predisposition or newly diagnosed hypertension

Figures & data

Figure 1. Illustration of compressed resting and thermal flow records. RF, resting flow; HF, heat flow; MHF, maximal heat flow.

Table I. Characteristics of the study groups.

	NT(−) (n=17)	NT(+) (n=22)	HT (n=31)	p
Age (years)	34.82±13.88	34.32±8.64	37.97±9.19
Male gender (%)	41.2	50.0	67.7
Body mass index (kg/m^2)	22.03±2.40	23.25±2.72	25.30±3.34**	0.002
Pulse wave velocity (m/s)	8.77±1.79	7.73±1.46	8.89±2.14
Insulin (μU/ml)	5.63±1.69	7.50±5.79	8.19±3.33*	0.03
Endothelin (pg/ml)	0.82±0.23	0.83±0.23	0.86±0.27
Red blood cell count (number/mm^3)	4.69±0.37	4.70±0.36	4.93±0.40
Hematocrit (%)	40.96±2.77	40.74±3.34	42.40±2.68
Glucose (mmol/l)	4.79±0.52	4.91±0.81	5.29±0.70*	0.01
Triglyceride (mmol/l)	1.18±0.49	1.24±0.74	1.91 ±1.27^#	0.04
Total cholesterol (mmol/l)	5.07±1.39	4.81±0.74	5.25±1.09
High-density lipoprotein (mmol/l)	1.54±0.28	1.56±0.57	1.30±0.31
Low-density lipoprotein (mmol/l)	2.99±1.34	2.73±0.56	3.03±1.03
Osmolarity (mosm/l)	271.82±9.34	268.02±6.27	268.66±5.20

NT, normotensive subjects; (−) negative family history of hypertension; (+) positive family history of hypertension, HT-sustained hypertension. *HI vs NT (−) – p=0.03; **HI vs NT (−) – p=0.002, ^#HT vs NT (+) – p=0.08.

Table II. Clinic and ambulatory blood pressure (BP) values in the study groups.

Values and variability (SD) of BP (mmHg)	NT(−) (n=17)	NT(+) (n=22)	HT (n=31)	p
Clinic systolic BP	122.1±11.5	121.3±8.6	152.6±8.3
Clinic diastolic BP	80.1±6.3	75.4±6.8	95.1±6.9	<0.001
Clinic mean arterial pressure	94.2±7.4	91.1 ±6.8	114.3±6.4	<0.001
24-h systolic BP	118.2±9.0	113.8±6.9	132.6±10.2	<0.001
Variability of 24-h systolic BP	12.7±2.7	11.2±2.9	13.1±3.3
24-h diastolic BP	72.9±6.0	71.1 ±4.7	83.2±8.3	<0.001
Variability of 24-h diastolic BP	10.9± 1.5	10.4±2.2	11.3±2.7
Daytime systolic BP	119.9±9.4	117.2±7.2	136.9±10.4	<0.001
Variability of daytime systolic BP	11.9±2.7	10.0±2.7	11.3±2.4	0.02
Daytime diastolic BP	74.8±7.0	74.4±5.3	87.3±8.7	<0.001
Variability of daytime diastolic BP	10.0±1.7	9.0±2.1	9.4±1.9	<0.001
Night-time systolic BP	112.9± 13.0	105.0±9.2	124.0±12.6	<0.001
Variability of night-time systolic BP	9.2±3.7	8.6±2.7	11.2±3.4	0.01
Night-time diastolic BP	67.3±9.0	62.4±6.3	74.5±9.8	<0.001
Variability of night-time diastolic BP	8.2±2.8	8.1±2.9	9.8±3.8

Table III. Characteristics of resting and thermal flows in study groups.

	NT(−) (n=17)	NT(+) (n=22)	HT (n=31)	p
Resting flow (AU)	9.73±3.82	8.84±4.23	10.15±3.88
Cutaneous vascular conductance of resting flow (AU/mmHg)	0.10±0.04	0.10±0.05	0.09±0.03
Heat flow (AU)	133.40±46.37	98.53±34.11	112.4±45.11
Cutaneous vascular conductance of heat flow (AU/mmHg)	1.44±0.55	1.09±0.42	0.99±0.40
Thermal stimulation ratio (%)	1475.27±590.30	1267.22±536.00	1211.55±597.97
Maximal heat flow (AU)	172.51±58.68	128.80±42.39	148.06±60.10
Cutaneous vascular conductance of maximal heat flow (AU/mmHg)	1.87±0.70	1.42±0.52	1.30±0.53*	0.02

AU, absolute units. *HT vs NT(−) – p=0.01.

Table IV. Power spectral density values of the different skin blood flowmotion frequency intervals in thermal condition among the study groups.

Frequency intervals	NT(−) (n=17)	NT(+) (n=22)	HT (n=31)	p
Total power (0.009–1.6 Hz) (AU^2/Hz)	1.17±0.38	0.84±0.41*	0.92±0.37	0.01
Endothelium activity (0.009–0.02 Hz) (AU^2/Hz)	9.78±4.42	7.96±3.73	8.75±3.41
Neurogenic activity (0.02–0.06 Hz) (AU^2/Hz)	2.74±1.13	2.03±1.15	2.09±0.97
Myogenic activity (0.06–0.2 Hz) (AU^2/Hz)	1.48±0.44	1.01±0.56**	1.26±0.58	0.03
Respiration activity (0.2–0.6 Hz) (AU^2/Hz)	0.61±0.20	0.41 ±0.22***	0.48±0.18	0.006
Heart activity (0.6–1.6 Hz) (AU^2/Hz)	1.14±0.39	0.81±0.41^#	0.86±0.39	0.02

AU, absolute units. NT(+) vs NT(−) *p=0.01; **p=0.03; ***p=0.004; ^#p=0.02.

Table V. Significant predictors of cutaneous vascular conductance of maximal heat flow and myogenic origin of skin blood flowmotion in multiple regression models.

	β coefficient	p
Cutaneous vascular conductance of maximal heat flow (corrected R^2=0.40; p<0.00004)
Body mass index	−0.37	0.005
Osmolarity	0.29	0.007
Night diastolic blood pressure	0.67	0.00002
Variability of night diastolic blood pressure	−0.43	0.0004
Diastolic blood pressure (clinic)	−0.51	0.0005
Myogenic activity (corrected R^2=0.39; p<0.00004)
Body mass index	−0.30	0.03
Pulse wave velocity	0.31	0.02
Cholesterol high-density lipoprotein	0.33	0.009
Night systolic blood pressure	−0.56	0.01
Night diastolic blood pressure	0.95	0.00006