Premium
Regulation of cerebral blood flow during exercise in men and women
Author(s) -
Clausen Mary,
Leddy John,
Willer Barry,
Pendergast David
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.804.19
Subject(s) - cerebral blood flow , cerebral autoregulation , cardiology , medicine , ventilation (architecture) , treadmill , vo2 max , perfusion , heart rate , anesthesia , autoregulation , blood pressure , physics , thermodynamics
Cerebral autoregulation (CA) maintains cerebral blood flow (CBF) constant over a wide range of perfusion pressures (MAP). However, arterial PCO 2 (P ET CO 2 ) may modify CBF if brain metabolism and total oxygen consumption (VO 2 ) are modified. During exercise MAP, VO 2 and VCO 2 are increased and may affect CBF. Female (13) and male (9) subjects completed a CO 2 sensitivity test at rest and a graded exercise treadmill test. Heart rate (HR), MAP, ventilation (V E ) and CBF velocity (CBFV) were measured in both tests. During rest CBFV (45%) and V E (221%) increased linearly with P ET CO 2 (58%). During exercise CBFV increased (31%) from 61 ± 16 cm/s to 78 ± 16 cm/s at 80% of VO 2 max. Once above the ventilatory threshold, CBFV decreased to 65 ± 16 cm/s at 100% VO 2 max. The changes in CBFV paralleled the changes in P ET CO 2 (36 ± 5 to 46 ± 6 to 36 ± 6 mmHg), despite a linear increase in MAP with VO 2 . Multiple linear regression indicated that P ET CO 2 was contributing more to CBFV than MAP (CBFV = 5.001 + (0.759 * P ET CO 2 ) + (0.313 * MAP)). During exercise CA did not maintain CBFV and P ET CO 2 strongly influenced it, thus ventilatory regulation (P ET CO 2 ) in exercise is critical in determining CBF. Resting CO 2 sensitivity did not predict exercise P ET CO 2 . Regulation of P ET CO 2 during exercise may explain the differences in CBF among individuals or conditions. One example may be the dysregulation of CBF in post concussion syndrome patients.