Regional neurohypophysial and hypothalamic blood flow in rats during hypercapnia

Journal Article · Mon Aug 01 04:00:00 EDT 1988 · Am. J. Physiol.; (United States)

OSTI ID:6801644

Bryan, Jr, R M; Myers, C L; Page, R B

Regional cerebral blood flow (rCBF) was measured in the neurohypophysis and hypothalamus in normocapnic and hypercapnic rats using (/sup 14/C)isopropyliodoamphetamine. Rats were surgically prepared using nitrous oxide and halothane and placed in plaster restraining casts. Hypercapnia was produced by increasing the fractional concentration of inspired CO/sub 2/ (FICO/sub 2/). rCBF in normocapnic rats was higher in the paraventricular nucleus, supraoptic nucleus, median eminence, and neural lobe than rates previously measured by use of diffusible tracers. During hypercapnia blood flow increased linearly with arterial PCO/sub 2/ (PACO/sub 2/) in all regions except the median eminence and neural lobe, which were not affected by hypercapnia. When rats were pretreated with phentolamine (1 mg/kg) to block the alpha-adrenergic receptors, blood flow in the median eminence and neural lobe increased significantly during hypercapnia. We conclude that blood flow in the cell bodies of the paraventricular nucleus and supraoptic nucleus is regulated differently during hypercapnia than blood flow in the nerve terminals in the median eminence and neural lobe. Furthermore, vasodilation produced by increased CO/sub 2/ is offset by alpha-receptor stimulation in the median eminence and neural lobe.

• Research Organization: Pennsylvania State Univ., Hershey (USA)
• OSTI ID: 6801644
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 255; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMPHETAMINES
ANALEPTICS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BLOOD FLOW
BODY
BRAIN
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CENTRAL NERVOUS SYSTEM
CENTRAL NERVOUS SYSTEM AGENTS
CHALCOGENIDES
DRUGS
LABELLED COMPOUNDS
MAMMALS
NERVES
NERVOUS SYSTEM
ORGANS
OXIDES
OXYGEN COMPOUNDS
PARTIAL PRESSURE
RATS
RODENTS
SYMPATHOMIMETICS
VASODILATION
VERTEBRATES