Protection of the blood-brain barrier by hypercapnia during acute hypertension

Journal Article · Fri Aug 01 04:00:00 EDT 1986 · Am. J. Physiol.; (United States)

OSTI ID:6281218

Baumbach, G L; Mayhan, W G; Heistad, D D

The purpose of this study was to examine effects of hypercapnia on susceptibility of the blood-brain barrier to disruption during acute hypertension. Two methods were used to test the hypothesis that cerebral vasodilation during hypercapnia increases disruption of the blood-brain barrier. First, permeability of the blood-brain barrier was measured in anesthetized cats with SVI-labeled serum albumin. Severe hypertension markedly increased permeability of the blood-brain barrier during normocapnia, but not during hypercapnia. The protective effect of hypercapnia was not dependent on sympathetic nerves. Second, in anesthetized rats, permeability of the barrier was quantitated by clearance of fluorescent dextran. Disruption of the blood-brain barrier during hypertension was decreased by hypercapnia. Because disruption of the blood-brain barrier occurred primarily in pial venules, the authors also measured pial venular diameter and pressure. Acute hypertension increased pial venular pressure and diameter in normocapnic rats. Hypercapnia alone increased pial venular pressure and pial venular diameter, and acute hypertension during hypercapnia further increased venular pressure. The magnitude of increase in pial venular pressure during acute hypertension was significantly less in hypercapnic than in normocapnic rats. They conclude that hypercapnia protects the blood-brain barrier. Possible mechanisms of this effect include attenuation of the incremental increase in pial venular pressure by hypercapnia or a direct effect on the blood-brain barrier not related to venous pressure.

• Research Organization: Univ. of Iowa College of Medicine, Iowa City
• OSTI ID: 6281218
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 251:2; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALBUMINS
ANESTHESIA
ANIMALS
BETA DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BLOOD PRESSURE
BLOOD-BRAIN BARRIER
CARDIOVASCULAR AGENTS
CARDIOVASCULAR DISEASES
CATS
DAYS LIVING RADIOISOTOPES
DISEASES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
HYPERTENSION
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPES
MAMMALS
MEMBRANE TRANSPORT
NERVES
NERVOUS SYSTEM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PERMEABILITY
PHYSIOLOGY
PROTEINS
RADIOISOTOPES
SYMPTOMS
VASCULAR DISEASES
VASODILATION
VASODILATORS
VERTEBRATES