Faster spontaneous respiratory rate in normal men is associated with higher muscle sympathetic nerve activity (29 vs 17 bursts/min; P<0.001) and potentiated responses to hypoxia and hypercapnia.
Cross-Sectional (n=69)
Are muscle sympathetic nerve activity and chemoreflex sensitivity linked to spontaneous respiratory rate in normal men?
In healthy men, a faster spontaneous respiratory rate is associated with higher sympathetic nerve activity and increased chemoreflex sensitivity to hypoxia and hypercapnia.
Effect estimate: r=0.42
Absolute Event Rate: 29% vs 17%
p-value: p=<0.001
Respiration contributes importantly to short-term modulation of sympathetic nerve activity. However, the relationship between spontaneous breathing rate, chemoreflex function, and direct measures of sympathetic traffic in healthy humans has not been studied previously. We tested the hypothesis that muscle sympathetic nerve activity and chemoreflex sensitivity are linked independently to respiratory rate in normal subjects. We studied 69 normal male subjects aged 29.6+/-8.1 years. Subjects were subdivided according to the tertiles of respiratory rate distributions. Mean respiration rate was 10.6 breaths/min in the first tertile, 14.8 breaths/min in the second tertile, and 18.0 breaths/min in the third tertile. Subjects from the third tertile (faster respiratory rate) had greater sympathetic activity than subjects from the first tertile (slower respiratory rate; 29+/-3 versus 17+/-2 bursts/min; P<0.001). Stepwise multiple linear regression analysis revealed that only respiratory rate was linked independently to sympathetic activity (r=0.42; P<0.001). In comparison to subjects with slow respiratory rate, subjects with fast respiratory rate had greater increases in minute ventilation during both hypercapnia (7.3+/-0.8 versus 3.2+/-1.0 L/min; P=0.005) and hypoxia (5.7+/-0.8 versus 2.4+/-0.7 L/min; P=0.007). Muscle sympathetic nerve activity and chemoreflex sensitivity are linked to spontaneous respiratory rate in normal humans. Faster respiratory rate is associated with higher levels of sympathetic traffic and potentiated responses to hypoxia and hypercapnia. Spontaneous breathing frequency, central sympathetic outflow, and chemoreflex sensitivity exhibit significant and hitherto unrecognized interactions in the modulation of neural circulatory control.
Narkiewicz et al. (Mon,) conducted a cross-sectional in Healthy subjects (n=69). Faster respiratory rate (third tertile) vs. Slower respiratory rate (first tertile) was evaluated on Muscle sympathetic nerve activity (bursts/min) (r=0.42, p=<0.001). Faster spontaneous respiratory rate in normal men is associated with higher muscle sympathetic nerve activity (29 vs 17 bursts/min; P<0.001) and potentiated responses to hypoxia and hypercapnia.