Time delay of baroreflex control and oscillatory pattern of sympathetic activity in patients with metabolic syndrome and obstructive sleep apnea.
The incidence and strength of muscle sympathetic nerve activity (MSNA) depend on the magnitude (gain) and latency (time delay) of the arterial baroreflex control (ABR). However, the impact of metabolic syndrome (MetS) and obstructive sleep apnea (OSA) on oscillatory pattern of MSNA and time delay of the ABR of sympathetic activity is unknown. We tested the hypothesis that MetS and OSA would impair the oscillatory pattern of MSNA and the time delay of the ABR of sympathetic activity. Forty-three patients with MetS were allocated into two groups according to the presence of OSA (MetS + OSA, n = 21; and MetS - OSA, n = 22). Twelve aged-paired healthy controls (C) were also studied. OSA (apnea-hypopnea index > 15 events/h) was diagnosed by polysomnography. We recorded MSNA (microneurography), blood pressure (beat-to-beat basis), and heart rate (EKG). Oscillatory pattern of MSNA was evaluated by autoregressive spectral analysis and the ABR of MSNA (ABRMSNA, sensitivity and time delay) by bivariate autoregressive analysis. Patients with MetS + OSA had decreased oscillatory pattern of MSNA compared with MetS - OSA (P < 0.01) and C (P < 0.001). The sensitivity of the ABRMSNA was lower and the time delay was greater in MetS + OSA compared with MetS - OSA (P < 0.001 and P < 0.01, respectively) and C (P < 0.001 and P < 0.001, respectively). Patients with MetS - OSA showed decreased oscillatory pattern of MSNA compared with C (P < 0.01). The sensitivity of the ABRMSNA was lower in MetS - OSA than in C group (P < 0.001). In conclusion, MetS decreases the oscillatory pattern of MSNA and the magnitude of the ABRMSNA. OSA exacerbates these autonomic dysfunctions and further increases the time delay of the baroreflex response of MSNA.
Heart Institute (Instituto do Coração University of Sao Paulo Medical School, Sao Paulo, Brazil.
Edgar
E
Toschi-Dias
Ivani C
IC
Trombetta
Valdo J
VJ
Dias da Silva
Cristiane
C
Maki-Nunes
Felipe X
FX
Cepeda
Maria-Janieire N N
MJ
Alves
Luciano F
LF
Drager
Geraldo
G
Lorenzi-Filho
Carlos E
CE
Negrao
Maria Urbana P B
MU
Rondon
D000328:Adult; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure; D016022:Case-Control Studies; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000503:physiopathology*; D008875:Middle Aged; D017286:Polysomnography; D011930:Reaction Time; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000503:physiopathology*