Loading...
Please wait, while we are loading the content...
Similar Documents
Autonomic nervous system influence on arterial baroreflex control of heart rate during exercise in humans (2005)
| Content Provider | CiteSeerX |
|---|---|
| Author | Ogoh, Shigehiko Fisher, James P. Dawson, Ellen A. White, Michael J. Secher, Niels H. Raven, Peter B. |
| Abstract | A combination of sympathoexcitation and vagal withdrawal increases heart rate (HR) during exercise, however, their specific contribution to arterial baroreflex sensitivity remains unclear. Eight subjects performed 25 min bouts of exercise at a HR of 90, 120, and 150 beats min−1, respectively, with and without metoprolol (0.16 ± 0.01 mg kg−1; mean ± S.E.M.) or glycopyrrolate (12.6 ± 1.6µg kg−1). Carotid baroreflex (CBR) function was determined using 5 s pulses of neck pressure (NP) and neck suction (NS) from +40 to −80 Torr, while transfer function gain (GTF) was calculated to assess the linear dynamic relationship between mean arterial pressure and HR. Spontaneous baroreflex sensitivity (SBR) was evaluated as the slope of sequences of three consecutive beats in which systolic blood pressure and the R–R interval of the ECG either increased or decreased, in a linear fashion. The β-1 adrenergic blockade decreased and vagal cardiac blockade increased HR both at rest and during exercise (P < 0.05). The gain at the operating point of the modelled reflex function curve (GOP) obtained using NP and NS decreased with workload independent of β-1 adrenergic blockade. In contrast, vagal blockade decreased GOP from −0.40 ± 0.04 to −0.06 ± 0.01 beats min−1 mmHg−1 at rest (P < 0.05). Furthermore, as workload increased both GOP and SBR, and GOP and GTF were correlated |
| File Format | |
| Journal | The Journal of Physiology Online |
| Language | English |
| Publisher Date | 2005-01-01 |
| Access Restriction | Open |
| Subject Keyword | Arterial Baroreflex Control Heart Rate Autonomic Nervous System Influence Adrenergic Blockade Spontaneous Baroreflex Sensitivity Modelled Reflex Function Curve Eight Subject Carotid Baroreflex Operating Point Systolic Blood Pressure Vagal Cardiac Blockade Vagal Blockade Linear Dynamic Relationship Transfer Function Gain Min Bout Specific Contribution Consecutive Beat Mean Arterial Pressure Vagal Withdrawal Increase Heart Rate Mg Kg Neck Pressure Mean S.e.m. Arterial Baroreflex Sensitivity Linear Fashion |
| Content Type | Text |
| Resource Type | Article |
