Phenylephrine decreases frontal lobe oxygenation at rest but not during moderately intense exercise

Patrice Brassard; Thomas Seifert; Mads Wissenberg; Peter M Jensen; Christian K Hansen; Niels H Secher; Patrice Brassard; Thomas Seifert; Mads Wissenberg; Peter M. Jensen; Christian K Hansen; Niels H Secher

doi:10.1152/japplphysiol.01206.2009

Phenylephrine decreases frontal lobe oxygenation at rest but not during moderately intense exercise

Patrice Brassard, Thomas Seifert, Mads Wissenberg, Peter M Jensen, Christian K Hansen, Niels H Secher, Patrice Brassard, Thomas Seifert, Mads Wissenberg, Peter M. Jensen, Christian K Hansen, Niels H Secher

43 Citations (Scopus)

Abstract

Whether sympathetic activity influences cerebral blood flow (CBF) and oxygenation remains controversial. The influence of sympathetic activity on CBF and oxygenation was evaluated by the effect of phenylephrine on middle cerebral artery (MCA) mean flow velocity (V_mean) and the nearinfrared spectroscopy-derived frontal lobe oxygenation. (Sc_O2) at rest and during exercise. At rest, nine healthy male subjects received bolus injections of phenylephrine (0.1, 0.25, and 0.4 mg), and changes in mean arterial pressure (MAP), MCA V_mean, internal jugular venous O₂ saturation (Sjv_O2), Sc_O2, and arterial PCO₂ (Pa _CO2) were measured and the cerebral metabolic rate for O₂ (CMR_O2) was calculated. In randomized order, a bolus of saline or 0.3 mg of phenylephrine was then injected during semisupine cycling, eliciting a low (∼110 beats/ min) or a high (∼150 beats/min) heart rate. At rest, MAP and MCA V_mean, increased ∼20% (P < 0.001) and ∼10% (P < 0.001 for 0.25 mg of phenylephrine and P < 0.05 for 0.4 mg of phenylephrine), respectively. Sc_O2 then decreased ∼7% (P < 0.001). Phenylephrine had no effect on Sjv_O2, Pa_CO2, or CMR_O2. MAP increased after the administration of phenylephrine during low-intensity exercise (∼15%), but this was attenuated (∼10%) during high-intensity exercise (P < 0.001). The reduction in Sc_O2 after administration of phenylephrine was attenuated during low-intensity exercise (-5%, P < 0.001) and abolished during high-intensity exercise (-3%, P = not significant), where Pa_CO2 decreased 7% (P < 0.05) and CMR _O2 increased 17% (P < 0.05). These results suggest that the administration of phenylephrine reduced Sc_O2 but that the increased cerebral metabolism needed for moderately intense exercise eliminated that effect.

Original language	English
Journal	Journal of Applied Physiology
Volume	108
Issue number	6
Pages (from-to)	1472-8
Number of pages	7
ISSN	8750-7587
DOIs	https://doi.org/10.1152/japplphysiol.01206.2009
Publication status	Published - 1 Jun 2010

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10.1152/japplphysiol.01206.2009

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Brassard, P., Seifert, T., Wissenberg, M., Jensen, P. M., Hansen, C. K., Secher, N. H., Brassard, P., Seifert, T., Wissenberg, M., Jensen, P. M., Hansen, C. K., & Secher, N. H. (2010). Phenylephrine decreases frontal lobe oxygenation at rest but not during moderately intense exercise. Journal of Applied Physiology, 108(6), 1472-8. https://doi.org/10.1152/japplphysiol.01206.2009

@article{7a46c100803a11df928f000ea68e967b,

title = "Phenylephrine decreases frontal lobe oxygenation at rest but not during moderately intense exercise",

abstract = "Whether sympathetic activity influences cerebral blood flow (CBF) and oxygenation remains controversial. The influence of sympathetic activity on CBF and oxygenation was evaluated by the effect of phenylephrine on middle cerebral artery (MCA) mean flow velocity (Vmean) and the nearinfrared spectroscopy-derived frontal lobe oxygenation. (ScO2) at rest and during exercise. At rest, nine healthy male subjects received bolus injections of phenylephrine (0.1, 0.25, and 0.4 mg), and changes in mean arterial pressure (MAP), MCA Vmean, internal jugular venous O2 saturation (SjvO2), ScO2, and arterial PCO2 (Pa CO2) were measured and the cerebral metabolic rate for O2 (CMRO2) was calculated. In randomized order, a bolus of saline or 0.3 mg of phenylephrine was then injected during semisupine cycling, eliciting a low (∼110 beats/ min) or a high (∼150 beats/min) heart rate. At rest, MAP and MCA Vmean, increased ∼20% (P < 0.001) and ∼10% (P < 0.001 for 0.25 mg of phenylephrine and P < 0.05 for 0.4 mg of phenylephrine), respectively. ScO2 then decreased ∼7% (P < 0.001). Phenylephrine had no effect on SjvO2, PaCO2, or CMRO2. MAP increased after the administration of phenylephrine during low-intensity exercise (∼15%), but this was attenuated (∼10%) during high-intensity exercise (P < 0.001). The reduction in ScO2 after administration of phenylephrine was attenuated during low-intensity exercise (-5%, P < 0.001) and abolished during high-intensity exercise (-3%, P = not significant), where PaCO2 decreased 7% (P < 0.05) and CMR O2 increased 17% (P < 0.05). These results suggest that the administration of phenylephrine reduced ScO2 but that the increased cerebral metabolism needed for moderately intense exercise eliminated that effect.",

author = "Patrice Brassard and Thomas Seifert and Mads Wissenberg and Jensen, {Peter M} and Hansen, {Christian K} and Secher, {Niels H} and Patrice Brassard and Thomas Seifert and Mads Wissenberg and Jensen, {Peter M.} and Hansen, {Christian K} and Secher, {Niels H}",

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doi = "10.1152/japplphysiol.01206.2009",

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T1 - Phenylephrine decreases frontal lobe oxygenation at rest but not during moderately intense exercise

AU - Brassard, Patrice

AU - Seifert, Thomas

AU - Wissenberg, Mads

AU - Jensen, Peter M

AU - Hansen, Christian K

AU - Secher, Niels H

AU - Brassard, Patrice

AU - Seifert, Thomas

AU - Wissenberg, Mads

AU - Jensen, Peter M.

AU - Hansen, Christian K

AU - Secher, Niels H

PY - 2010/6/1

Y1 - 2010/6/1

N2 - Whether sympathetic activity influences cerebral blood flow (CBF) and oxygenation remains controversial. The influence of sympathetic activity on CBF and oxygenation was evaluated by the effect of phenylephrine on middle cerebral artery (MCA) mean flow velocity (Vmean) and the nearinfrared spectroscopy-derived frontal lobe oxygenation. (ScO2) at rest and during exercise. At rest, nine healthy male subjects received bolus injections of phenylephrine (0.1, 0.25, and 0.4 mg), and changes in mean arterial pressure (MAP), MCA Vmean, internal jugular venous O2 saturation (SjvO2), ScO2, and arterial PCO2 (Pa CO2) were measured and the cerebral metabolic rate for O2 (CMRO2) was calculated. In randomized order, a bolus of saline or 0.3 mg of phenylephrine was then injected during semisupine cycling, eliciting a low (∼110 beats/ min) or a high (∼150 beats/min) heart rate. At rest, MAP and MCA Vmean, increased ∼20% (P < 0.001) and ∼10% (P < 0.001 for 0.25 mg of phenylephrine and P < 0.05 for 0.4 mg of phenylephrine), respectively. ScO2 then decreased ∼7% (P < 0.001). Phenylephrine had no effect on SjvO2, PaCO2, or CMRO2. MAP increased after the administration of phenylephrine during low-intensity exercise (∼15%), but this was attenuated (∼10%) during high-intensity exercise (P < 0.001). The reduction in ScO2 after administration of phenylephrine was attenuated during low-intensity exercise (-5%, P < 0.001) and abolished during high-intensity exercise (-3%, P = not significant), where PaCO2 decreased 7% (P < 0.05) and CMR O2 increased 17% (P < 0.05). These results suggest that the administration of phenylephrine reduced ScO2 but that the increased cerebral metabolism needed for moderately intense exercise eliminated that effect.

AB - Whether sympathetic activity influences cerebral blood flow (CBF) and oxygenation remains controversial. The influence of sympathetic activity on CBF and oxygenation was evaluated by the effect of phenylephrine on middle cerebral artery (MCA) mean flow velocity (Vmean) and the nearinfrared spectroscopy-derived frontal lobe oxygenation. (ScO2) at rest and during exercise. At rest, nine healthy male subjects received bolus injections of phenylephrine (0.1, 0.25, and 0.4 mg), and changes in mean arterial pressure (MAP), MCA Vmean, internal jugular venous O2 saturation (SjvO2), ScO2, and arterial PCO2 (Pa CO2) were measured and the cerebral metabolic rate for O2 (CMRO2) was calculated. In randomized order, a bolus of saline or 0.3 mg of phenylephrine was then injected during semisupine cycling, eliciting a low (∼110 beats/ min) or a high (∼150 beats/min) heart rate. At rest, MAP and MCA Vmean, increased ∼20% (P < 0.001) and ∼10% (P < 0.001 for 0.25 mg of phenylephrine and P < 0.05 for 0.4 mg of phenylephrine), respectively. ScO2 then decreased ∼7% (P < 0.001). Phenylephrine had no effect on SjvO2, PaCO2, or CMRO2. MAP increased after the administration of phenylephrine during low-intensity exercise (∼15%), but this was attenuated (∼10%) during high-intensity exercise (P < 0.001). The reduction in ScO2 after administration of phenylephrine was attenuated during low-intensity exercise (-5%, P < 0.001) and abolished during high-intensity exercise (-3%, P = not significant), where PaCO2 decreased 7% (P < 0.05) and CMR O2 increased 17% (P < 0.05). These results suggest that the administration of phenylephrine reduced ScO2 but that the increased cerebral metabolism needed for moderately intense exercise eliminated that effect.

U2 - 10.1152/japplphysiol.01206.2009

DO - 10.1152/japplphysiol.01206.2009

M3 - Journal article

C2 - 20223999

SN - 8750-7587

VL - 108

SP - 1472

EP - 1478

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

IS - 6

ER -

Phenylephrine decreases frontal lobe oxygenation at rest but not during moderately intense exercise

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