Reduced exercise capacity in systemic sclerosis patients without pulmonary involvement.

OBJECTIVE: To evaluate the exercise capacity of women with systemic sclerosis (SSc) without pulmonary involvement using a cardiopulmonary stress test. METHODS: Thirteen consecutive female SSc patients [mean age 40.8+/-14 years, mean body mass index (BMI) 25.5+/-3.7 kg/m2] without pulmonary and cardiac involvement and 13 healthy sedentary female controls (mean age 41.6+/-9.1 years, mean BMI 23.7+/-3.8 kg/m2) matched by age and BMI underwent a maximum cardiopulmonary stress test (Bruce protocol). The following parameters were analysed: peak oxygen uptake (VO2peak), anaerobic threshold (AT), respiratory compensation point (RCP) and metabolic equivalent (MET) of the VO2peak. Comparisons between groups were analysed using the Student t-test. RESULTS: Forced vital capacity (FVC; 92.2+/-14.2% predicted) and carbon monoxide diffusion lung capacity (DL CO; 85.8+/-5.8% predicted) were within the normal range in SSc patients. VO2peak of SSc patients was significantly reduced in comparison to the control group (19.8+/-4.6 vs. 23.7+/-4.5 mL/kg/min, p = 0.04). SSc patients also had a significant reduction in MET at peak exercise (5.6+/-1.3 vs. 6.7+/-1.3 MET, p = 0.04) and a significant shorter time interval between AT and RCP compared to the control group (112.6+/-95.6 vs. 164.0+/-65.3 s, p = 0.03). CONCLUSION: SSc patients without pulmonary impairment have reduced exercise capacity. Abnormal vascular response to exercise may account for this finding, as the vascular system is one of the major target organs in this pathological condition.

Alpha2B-adrenergic receptor deletion polymorphism and cardiac autonomic nervous system responses to exercise in obese women.

OBJECTIVE: To investigate the association of short form (Glu9/Glu9) of the 12Glu9 deletion polymorphism of the alpha2B-adrenergic receptor (alpha2B-AR) gene polymorphism with the cardiac autonomic responsiveness during sustained isometric handgrip exercise. DESIGN: Cross-sectional clinical study. SUBJECTS: In all, 97 normotensive obese women (body mass index (BMI) = 33.2 kg/m2). Of these, 78 (80.41%) were genotyped as Glu12/Glu12, 13 (13.40%) as Glu12/Glu9 and six (6.19%) as Glu9/Glu9 form. MEASUREMENTS: The sympathovagal balance was assessed by means of power spectral analysis of heart rate variability at rest and during sustained isometric handgrip exercise at 30% of maximal voluntary handgrip contraction for 3 min. Two spectral components were analysed: low-frequency component reflecting sympathetic efferent activity and high-frequency power (HFnu) reflecting parasympathetic modulation. In addition, a normalized low-frequency power (LFnu) and HFnu were analysed. Genotypes were determined by polymerase chain reaction followed by agarose gel electrophoresis. RESULTS: There were no differences in baseline measurements among groups. The absolute level of LFnu throughout handgrip exercise was significantly lower in Glu9/Glu9 subjects compared with other genotypes, while the decline of absolute HFnu was significantly smaller compared with Glu12/Glu12 genotype. CONCLUSION: These findings suggest that 12Glu9 deletion polymorphism of the alpha2B-AR gene (Glu9/Glu9 genotype) might result in reduced autonomic responsiveness by altering cardiac sympathetic and vagal function during sustained handgrip exercise in normotensive obese women.

Effect of aging on carotid artery stiffness and baroreflex sensitivity during head-out water immersion in man.

To examine the possible age-related blood pressure (BP) deregulation in response to central hypervolemia, we measured spontaneous baroreflex sensitivity (SBRS), carotid arterial compliance (CC), and R-R interval coefficient of variation (RRICV) during basal and thermoneutral resting head-out-of-water immersion (HOWI) in 7 young (YG = 24.0 +/- 0.8 years) and 6 middle-aged/older (OL = 59.3 +/- 1.3 years) healthy men. Compared with basal conditions (YG = 19.6 +/- 4.0 vs OL = 6.1 +/- 1.5 ms/mmHg, P < 0.05), SBRS remained higher in YG than OL during rest HOWI (YG = 23.6 +/- 6.6 vs OL = 9.3 +/- 2.1 ms/mmHg, P < 0.05). The RRICV was significantly different between groups (YG = 6.5 +/- 1.4 vs OL = 2.8 +/- 0.4%, P < 0.05) under HOWI. The OL group had no increase in CC, but a significant increase in systolic BP (basal = 115.3 +/- 4.4 vs water = 129.3 +/- 5.3 mmHg, P < 0.05) under HOWI. In contrast, the YG group had a significant increase in CC (basal = 0.16 +/- 0.01 vs water = 0.17 +/- 0.02 mm(2)/mmHg, P < 0.05) with no changes in systolic BP. SBRS was positively related to CC (r = 0.58, P < 0.05 for basal vs r = 0.62, P < 0.05 for water). Our data suggest that age-related vagal dysfunction and reduced CC may be associated with SBRS differences between YG and OL groups, and with BP elevation during HOWI in healthy older men.

Effect of aging on carotid artery stiffness and baroreflex sensitivity during head-out water immersion in man

To examine the possible age-related blood pressure (BP) deregulation in response to central hypervolemia, we measured spontaneous baroreflex sensitivity (SBRS), carotid arterial compliance (CC), and R-R interval coefficient of variation (RRICV) during basal and thermoneutral resting head-out-of-water immersion (HOWI) in 7 young (YG = 24.0 ± 0.8 years) and 6 middle-aged/older (OL = 59.3 ± 1.3 years) healthy men. Compared with basal conditions (YG = 19.6 ± 4.0 vs OL = 6.1 ± 1.5 ms/mmHg, P < 0.05), SBRS remained higher in YG than OL during rest HOWI (YG = 23.6 ± 6.6 vs OL = 9.3 ± 2.1 ms/mmHg, P < 0.05). The RRICV was significantly different between groups (YG = 6.5 ± 1.4 vs OL = 2.8 ± 0.4 percent, P < 0.05) under HOWI. The OL group had no increase in CC, but a significant increase in systolic BP (basal = 115.3 ± 4.4 vs water = 129.3 ± 5.3 mmHg, P < 0.05) under HOWI. In contrast, the YG group had a significant increase in CC (basal = 0.16 ± 0.01 vs water = 0.17 ± 0.02 mm²/mmHg, P < 0.05) with no changes in systolic BP. SBRS was positively related to CC (r = 0.58, P < 0.05 for basal vs r = 0.62, P < 0.05 for water). Our data suggest that age-related vagal dysfunction and reduced CC may be associated with SBRS differences between YG and OL groups, and with BP elevation during HOWI in healthy older men.