Cerebral perfusion, oxygenation and metabolism during exercise in young and elderly individuals

TY - JOUR

T1 - Cerebral perfusion, oxygenation and metabolism during exercise in young and elderly individuals

AU - Fisher, James P

AU - Hartwich, Doreen

AU - Seifert, Thomas

AU - Olesen, Niels

AU - McNulty, Clare L

AU - Nielsen, Henning M Bay

AU - van Lieshout, Johannes J

AU - Secher, Niels H

PY - 2013/4

Y1 - 2013/4

N2 - We evaluated cerebral perfusion, oxygenation and metabolism in 11 young (22 ± 1 years) and nine older (66 ± 2 years) individuals at rest and during cycling exercise at low (25%Wmax), moderate (50%Wmax), high (75%Wmax) and exhaustive (100%Wmax) workloads. Mean middle cerebral artery blood velocity (MCA Vmean), mean arterial pressure (MAP), cardiac output (CO) and partial pressure of arterial carbon dioxide () were measured. Blood samples were obtained from the right internal jugular vein and brachial artery to determine concentration differences for oxygen (O2), glucose and lactate across the brain. The molar ratio between cerebral uptake of O2versus carbohydrate (O2-carbohydrate index; O2/[glucose +1/2 lactate]; OCI), the cerebral metabolic rate of O2 (CMRO2) and changes in mitochondrial O2 tension () were calculated. 100%Wmax was ∼33% lower in the older group. Exercise increased MAP and CO in both groups (P < 0.05 vs. rest), but at each intensity MAP was higher and CO lower in the older group (P < 0.05). MCA Vmean, and cerebral vascular conductance index (MCA Vmean/MAP) were lower in the older group at each exercise intensity (P < 0.05). In contrast, young and older individuals exhibited similar increases in CMRO2 (by ∼30 μmol (100 g-1) min-1), and decreases in OCI (by ∼1.5) and (by ∼10 mmHg) during exercise at ≥75%Wmax. Thus, despite the older group having reduced cerebral perfusion and maximal exercise capacity, cerebral oxygenation and uptake of lactate and glucose are similar during exercise in young and older individuals.

AB - We evaluated cerebral perfusion, oxygenation and metabolism in 11 young (22 ± 1 years) and nine older (66 ± 2 years) individuals at rest and during cycling exercise at low (25%Wmax), moderate (50%Wmax), high (75%Wmax) and exhaustive (100%Wmax) workloads. Mean middle cerebral artery blood velocity (MCA Vmean), mean arterial pressure (MAP), cardiac output (CO) and partial pressure of arterial carbon dioxide () were measured. Blood samples were obtained from the right internal jugular vein and brachial artery to determine concentration differences for oxygen (O2), glucose and lactate across the brain. The molar ratio between cerebral uptake of O2versus carbohydrate (O2-carbohydrate index; O2/[glucose +1/2 lactate]; OCI), the cerebral metabolic rate of O2 (CMRO2) and changes in mitochondrial O2 tension () were calculated. 100%Wmax was ∼33% lower in the older group. Exercise increased MAP and CO in both groups (P < 0.05 vs. rest), but at each intensity MAP was higher and CO lower in the older group (P < 0.05). MCA Vmean, and cerebral vascular conductance index (MCA Vmean/MAP) were lower in the older group at each exercise intensity (P < 0.05). In contrast, young and older individuals exhibited similar increases in CMRO2 (by ∼30 μmol (100 g-1) min-1), and decreases in OCI (by ∼1.5) and (by ∼10 mmHg) during exercise at ≥75%Wmax. Thus, despite the older group having reduced cerebral perfusion and maximal exercise capacity, cerebral oxygenation and uptake of lactate and glucose are similar during exercise in young and older individuals.

U2 - 10.1113/jphysiol.2012.244905

DO - 10.1113/jphysiol.2012.244905

M3 - Journal article

C2 - 23230234

SN - 0022-3751

JO - Journal of Physiology

JF - Journal of Physiology

ER -