Table 1.
Subject characteristics
| Variable | Young Men | Young Women | MA/O Men | MA/O Women | P Value |
|---|---|---|---|---|---|
| n | 40 | 25 | 12 | 16 | |
| Age, years | 27 ± 1 | 30 ± 1 | 60 ± 3*† | 56 ± 1*† | <0.001 |
| Age range, years | 19–44 | 20–44 | 47–73 | 46–66 | – |
| BMI, kg·m2 | 28 ± 1 | 28 ± 1 | 29 ± 1 | 29 ± 1 | 0.411 |
| Glucose, mg/dL | 92 ± 1 | 93 ± 4 | 97 ± 2 | 100 ± 9 | 0.201 |
| Insulin, µIU/mL | 12.2 ± 1.7 | 9.3 ± 1.4 | 5.9 ± 0.8 | 10.1 ± 2.2 | 0.065 |
| Triglycerides, mg/dL | 99 ± 8 | 72 ± 7 | 82 ± 11 | 92 ± 13 | 0.298 |
| LDL, mg/dL | 106 ± 4 | 89 ± 6 | 106 ± 10 | 101 ± 7 | 0.142 |
| HDL, mg/dL | 43 ± 2 | 62 ± 3* | 60 ± 2* | 59 ± 3* | <0.001 |
| Total cholesterol, mg/dL | 173 ± 6 | 165 ± 6 | 182 ± 9 | 178 ± 7 | 0.426 |
| MSNA | |||||
| Burst incidence, bursts/100 heartbeats | 31 ± 3 | 24 ± 3 | 58 ± 7*† | 43 ± 4† | <0.001 |
| Burst frequency, bursts/min | 19 ± 2 | 15 ± 2 | 33 ± 4*† | 26 ± 2† | <0.001 |
| Common carotid artery | |||||
| IMT, mm | 0.41 ± 0.02 | 0.40 ± 0.02 | 0.52 ± 0.04*† | 0.50 ± 0.02*† | 0.001 |
| Lumen diameter, mm | 6.45 ± 0.10 | 6.03 ± 0.08* | 6.66 ± 0.25† | 6.33 ± 0.18 | 0.006 |
| IMT-to-lumen ratio | 0.064 ± 0.003 | 0.067 ± 0.003 | 0.079 ± 0.008 | 0.079 ± 0.004* | 0.009 |
| Cardiovascular variables | |||||
| Resting heart rate, beats/min | 63 ± 1 | 62 ± 2 | 56 ± 3 | 61 ± 2 | 0.168 |
| Resting systolic BP, mmHg | 125 ± 2 | 118 ± 2 | 132 ± 5 | 129 ± 5 | 0.060 |
| Resting diastolic BP, mmHg | 70 ± 2 | 69 ± 2 | 79 ± 2*† | 76 ± 2 | 0.006 |
| Resting mean BP, mmHg | 88 ± 2 | 85 ± 2 | 96 ± 3† | 94 ± 3† | 0.006 |
| 24-h systolic BP, mmHg | 128 ± 1 | 122 ± 2 | 130 ± 4 | 125 ± 4 | 0.095 |
| 24-h diastolic BP, mmHg | 75 ± 1 | 74 ± 1 | 80 ± 2 | 75 ± 3 | 0.123 |
| 24-h mean BP, mmHg | 92 ± 1 | 91 ± 2 | 96 ± 3 | 93 ± 3 | 0.295 |
| History | |||||
| HTN or borderline HTN, n (%) | 11 (28) | 3 (12) | 3 (25) | 6 (38) | 0.295 |
| Family HTN, n (%) | 17 (43) | 17 (68) | 6 (50) | 12 (75) | 0.076 |
| Smoking, n (%) | 6 (15) | 8 (32) | 1 (8) | 3 (19) | 0.268 |
| Cardiovascular medications | |||||
| Statin, n (%) | 0 (0) | 0 (0) | 1 (8) | 1 (6) | – |
| Diuretic, n (%) | 0 (0) | 2 (8) | 0 (0) | 1 (6) | – |
| ACE inhibitor, n (%) | 2 (5) | 0 (0) | 0 (0) | 1 (6) | – |
Values are means ± SE. History indicates self-reported history. ACE, angiotensin-converting enzyme; BMI, body mass index; BP, blood pressure; LDL, low-density lipoprotein; HDL, high-density lipoprotein; HTN, hypertension; IMT, intima-media thickness; MA/O, middle-aged/older; MSNA, muscle sympathetic nerve activity. P values are one-way ANOVA results across 4 groups.
*
P < 0.05 vs. young men,
†
P < 0.05 vs. young women.