Reduction of cerebrovascular reactivity during hypercapnia

The effects on cerebral blood flow of alpha- or beta-adrenergic receptor stimulation of cerebral vessels were examined in 13 unanesthetized goats before and during hypercapnia produced by inhalation of 10% CO2 in air. This procedure increased the PCO2 from 34 to 52 and was accompanied by a fall in pH from 7.39 to 7.26. Electrical stimulation of the cervical sympathetic nerve and injections of norepinephrine and tyramine into the internal maxillary artery produced reductions in cerebral blood flow that were abolished or reduced in hypercapnia. The increase in cerebral blood flow in response to beta-adrenergic stimulation with isoproterenol was also reduced. Hypercapnia caused a similar depression of the constrictor and dilatory effects of the nonadrenergic drugs vasopressin and diazoxide. The results show a decreased response of cerebral vessels to adrenergic and nonadrenergic stimuli in hypercapnia. The findings do not suggest any difference between the refractoriness of cerebral vessels in hypercapnia and that described in other vascular beds.

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The Effect of Stimulation of the Cervical Sympathetic Chain on Retinal Oxygen Tension and on Uveal, Retinal and Cerebral Blood Flow in Cats

Acta Physiologica Scandinavica ◽

10.1111/j.1748-1716.1973.tb05436.x ◽

1973 ◽

Vol 88 (1) ◽

pp. 84-94 ◽

Cited By ~ 132

Author(s):

Albert Alm ◽

Anders Bill

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Oxygen Tension ◽

Sympathetic Chain ◽

Cervical Sympathetic Chain ◽

Cervical Sympathetic ◽

Stimulation Of

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Cerebral blood flow and behavior during brain stimulation in the goat

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1977.232.5.h495 ◽

1977 ◽

Vol 232 (5) ◽

pp. H495-H499

Author(s):

M. Manrique ◽

E. Alborch ◽

J. M. Delgado

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Blood Flow ◽

Cerebral Blood Flow ◽

Arterial Blood Pressure ◽

Maxillary Artery ◽

Internal Maxillary Artery ◽

Arterial Blood ◽

And Behavior ◽

Stimulation Of

Cerebral blood flow, heart rate, arterial blood pressure, and behavior were studied in conscious goats during electrical stimulation of the diencephalon and mesencephalon. Stimulation of the subthalamic area produced a considerable increase in ipsilateral cerebral blood flow and heart rate, accompanied by either a small or a large increase in systemic arterial blood pressure. Cardiovascular effects were associated with changes in alertness. The increase in cerebral blood flow was partially abolished by previous administration of atropine directly into the internal maxillary artery. Stimulation of the mesencephalic reticular formation caused a marked increase in blood pressure with no change or with some decrease in cerebral blood flow. After administration of phentolamine into the internal maxillary artery, stimulation produced increase in cerebral blood flow. The behavioral response consisted of restlessness and attempted flight. These results suggest the existence of cholinergic vasodilator and adrenergic vasoconstrictor pathways to cerebral blood vessels that may be stimulated electrically.

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Effects of stimulation of cervical sympathetic trunks on the local cortical cerebral blood flow measured by laser doppler flowmetry in the rat

Neuroscience Research Supplements ◽

10.1016/0921-8696(90)90101-8 ◽

1990 ◽

Vol 15 ◽

pp. S23

Author(s):

Yuka Saeki ◽

Akio Sato ◽

Yuko Sato ◽

Andrzej Trzebski

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Laser Doppler Flowmetry ◽

Laser Doppler ◽

Doppler Flowmetry ◽

Cortical Cerebral Blood Flow ◽

Cervical Sympathetic ◽

Stimulation Of

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Effects of stimulation of cervical sympathetic trunks with various frequencies on the local cortical cerebral blood flow measured by laser doppler flowmetry in the rat.

The Japanese Journal of Physiology ◽

10.2170/jjphysiol.40.15 ◽

1990 ◽

Vol 40 (1) ◽

pp. 15-32 ◽

Cited By ~ 28

Author(s):

Yuka SAEKI ◽

Akio SATO ◽

Yuko SATO ◽

Andrzej TRZEBSKI

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Laser Doppler Flowmetry ◽

Laser Doppler ◽

Doppler Flowmetry ◽

Cortical Cerebral Blood Flow ◽

Cervical Sympathetic ◽

Stimulation Of

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Cerebral blood flow during fastigial pressor response in cats

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1990.258.3.h729 ◽

1990 ◽

Vol 258 (3) ◽

pp. H729-H733

Author(s):

J. L. Williams ◽

M. A. Murray ◽

K. A. Schalk ◽

D. D. Heistad

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Arterial Pressure ◽

Severe Hypertension ◽

Pressor Response ◽

Sympathetic Nerves ◽

Fastigial Nucleus ◽

Acute Hypertension ◽

Cervical Sympathetic ◽

Stimulation Of

We tested the hypotheses that electrical stimulation of the fastigial nucleus increases cerebral blood flow by a dilator mechanism, impairs autoregulation during increases in arterial pressure, and attenuates increases in cerebral blood flow during acute hypertension by activation of sympathetic nerves. Cerebral blood flow was measured with microspheres in anesthetized cats during control and moderate or severe hypertension produced by stimulation of the rostral fastigial nucleus. Cervical sympathetic nerves to one cerebral hemisphere were cut to compare responses in the innervated and denervated hemispheres. Fastigial stimulation at a level that raised arterial pressure from 94 +/- 10 (mean +/- SE) to 133 +/- 6 mmHg had no significant effect on cerebral blood flow. Autoregulation was preserved because cerebral vascular resistance increased approximately 40% during the fastigial pressure response. When mean arterial pressure was raised to 189 +/- 9 mmHg by stimulation of the fastigial nucleus, cerebral blood flow increased similarly in the denervated hemisphere and the hemisphere with intact sympathetic nerves. We conclude that stimulation of the fastigial nucleus in cats does not have a direct dilator effect on cerebral vessels, does not impair autoregulation during moderate hypertension, and does not attenuate increases in cerebral blood flow during severe hypertension by activation of sympathetic pathways.

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