TY - JOUR

T1 - Angiotensin converting enzyme inhibition and the upper limit of cerebral blood flow autoregulation

T2 - effect of sympathetic stimulation

AU - Waldemar, G

AU - Paulson, O B

AU - Barry, D I

AU - Knudsen, G M

PY - 1989/6

Y1 - 1989/6

N2 - The effect of stimulation of the cervical sympathetic ganglia on the upper limit of cerebral blood flow (CBF) autoregulation was studied in normotensive Wistar-Kyoto rats (WKY) and in spontaneously hypertensive rats (SHR) following intravenous administration of the angiotensin converting enzyme inhibitor captopril (10 mg/kg). CBF was measured using the intracarotid 133Xe injection method in halothane/nitrous oxide anaesthetized WKY and SHR. Arterial blood pressure was raised stepwise by the intravenous infusion of noradrenaline. Toward the end of the study, Evans blue was injected and the brains examined for gross blood-brain barrier breakdown. In SHR, sympathetic stimulation reextended the upper limit of CBF autoregulation, which was at a mean arterial blood pressure level of 120-139 mm Hg in the control group of eight SHR and above 170 mm Hg in the stimulated group of nine SHR. In the group of nine WKY subjected to sympathetic stimulation, the upper limit of CBF autoregulation was reached at a mean arterial blood pressure level of 110-129 mm Hg as opposed to 90-109 mm Hg in a previous unstimulated group of WKY. In the two groups subjected to sympathetic stimulation, there was no extravasation of Evans blue in any of the brains. In the control group of SHR, in which there had been marked increases in CBF, three out of eight brains had foci with extravasation of the dye. It is concluded that in normotensive and in hypertensive rats sympathetic stimulation attenuates the downward shift of the upper limit of CBF autoregulation, which is known to accompany intravenous administration of captopril.

AB - The effect of stimulation of the cervical sympathetic ganglia on the upper limit of cerebral blood flow (CBF) autoregulation was studied in normotensive Wistar-Kyoto rats (WKY) and in spontaneously hypertensive rats (SHR) following intravenous administration of the angiotensin converting enzyme inhibitor captopril (10 mg/kg). CBF was measured using the intracarotid 133Xe injection method in halothane/nitrous oxide anaesthetized WKY and SHR. Arterial blood pressure was raised stepwise by the intravenous infusion of noradrenaline. Toward the end of the study, Evans blue was injected and the brains examined for gross blood-brain barrier breakdown. In SHR, sympathetic stimulation reextended the upper limit of CBF autoregulation, which was at a mean arterial blood pressure level of 120-139 mm Hg in the control group of eight SHR and above 170 mm Hg in the stimulated group of nine SHR. In the group of nine WKY subjected to sympathetic stimulation, the upper limit of CBF autoregulation was reached at a mean arterial blood pressure level of 110-129 mm Hg as opposed to 90-109 mm Hg in a previous unstimulated group of WKY. In the two groups subjected to sympathetic stimulation, there was no extravasation of Evans blue in any of the brains. In the control group of SHR, in which there had been marked increases in CBF, three out of eight brains had foci with extravasation of the dye. It is concluded that in normotensive and in hypertensive rats sympathetic stimulation attenuates the downward shift of the upper limit of CBF autoregulation, which is known to accompany intravenous administration of captopril.

KW - Animals

KW - Captopril/pharmacology

KW - Cerebrovascular Circulation/drug effects

KW - Electric Stimulation

KW - Ganglia, Sympathetic/physiology

KW - Homeostasis/drug effects

KW - Hypertension/drug therapy

KW - Male

KW - Rats

KW - Rats, Inbred SHR

KW - Rats, Inbred WKY

KW - Sympathetic Nervous System/physiology

U2 - 10.1161/01.res.64.6.1197

DO - 10.1161/01.res.64.6.1197

M3 - Journal article

C2 - 2655965

VL - 64

SP - 1197

EP - 1204

JO - Circulation Research

JF - Circulation Research

SN - 0009-7330

IS - 6

ER -