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Dynamic time-varying analysis of heart rate and blood pressure variability in cats exposed to short-term chronic intermittent hypoxia.
Rey, Sergio; Tarvainen, Mika P; Karjalainen, Pasi A; Iturriaga, Rodrigo.
Affiliation
  • Rey S; Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
Am J Physiol Regul Integr Comp Physiol ; 295(1): R28-37, 2008 Jul.
Article in En | MEDLINE | ID: mdl-18463194
Chronic intermittent hypoxia (CIH) contributes to the development of hypertension in patients with obstructive sleep apnea and animal models. However, the early cardiovascular changes that precede CIH-induced hypertension are not completely understood. Nevertheless, it has been proposed that one of the possible contributing mechanisms to CIH-induced hypertension is a potentiation of carotid body (CB) hypoxic chemoreflexes. Therefore, we studied the dynamic responses of heart rate, blood pressure, and their variabilities during acute exposure to different levels of hypoxia after CIH short-term preconditioning (4 days) in cats. In addition, we measured baroreflex sensitivity (BRS) on the control of heart rate by noninvasive techniques. To assess the relationships among these indexes and CB chemoreflexes, we also recorded CB chemosensory discharges. Our data show that short-term CIH reduced BRS, potentiated the increase in heart rate induced by acute hypoxia, and was associated with a dynamic shift of heart rate variability (HRV) spectral indexes toward the low-frequency band. In addition, we found a striking linear correlation (r = 0.97) between the low-to-high frequency ratio of HRV and baseline. CB chemosensory discharges in the CIH-treated cats. Thus, our results suggest that cyclic hypoxic stimulation of the CB by short-term CIH induces subtle but clear selective alterations of HRV and BRS in normotensive cats.
Subject(s)

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Blood Pressure / Heart Rate / Hypoxia Type of study: Prognostic_studies Limits: Animals Language: En Journal: Am J Physiol Regul Integr Comp Physiol Journal subject: FISIOLOGIA Year: 2008 Document type: Article Affiliation country: Chile Country of publication: United States

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Blood Pressure / Heart Rate / Hypoxia Type of study: Prognostic_studies Limits: Animals Language: En Journal: Am J Physiol Regul Integr Comp Physiol Journal subject: FISIOLOGIA Year: 2008 Document type: Article Affiliation country: Chile Country of publication: United States