Mechanisms regulating neurohypophysial blood flow and function during isotonic volume expansion

M. N. Diringer, D. A. Wilson, Daniel F Hanley, Katherine Chih-Ching Wu, Paul W Ladenson, R. J. Traystman

Research output: Contribution to journalArticle

Abstract

Regional cerebral and neurohypophysial blood flow responses to isotonic extracellular fluid volume expansion were studied in pentobarbital-anesthetized dogs using radiolabeled microspheres. Measurements were made at baseline and after increasing pulmonary capillary wedge pressure by 8 ± 2 mmHg. Plasma arginine vasopressin (AVP) decreased by 50%, and neural lobe blood flow (NLBF) decreased by 47%. Blood flow through median eminence and other brain regions was unchanged. We investigated potential mechanisms responsible for the NLBF changes. Following control vagotomy, AVP concentration increased during the first hour and then returned to control values for hours 2 and 3, whereas NLBF was unchanged for the first hour and fell after 2 and 3 h. Vagus section abolished the decrease in NLBF but not the AVP response to volume expansion. The contribution of left atrial and pulmonary baroreceptors to this response was tested by inflation of a balloon in the left atria to produce a 13 ± 1 mmHg rise in atrial pressure. This led to a 20% reduction in NLBF, a 35% reduction in AVP concentration, and a 270% increase in plasma atrial natriuretic factor (ANF). However, ANF release does not account for the NLBF changes, since intravenous ANF infusion had no effect on NLBF or AVP concentration. These data suggest that the NLBF response to volume expansion is mediated by the vagus with input from multiple cardiopulmonary baroreceptors.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume262
Issue number1 31-1
StatePublished - 1992

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Posterior Pituitary Gland
Arginine Vasopressin
Atrial Natriuretic Factor
Pressoreceptors
Cerebrovascular Circulation
Median Eminence
Pulmonary Wedge Pressure
Atrial Pressure
Vagotomy
Extracellular Fluid
Economic Inflation
Pentobarbital
Heart Atria
Microspheres
Dogs
Lung
Brain

Keywords

  • Arginine vasopressin
  • Atrial distension
  • Atrial natriuretic factor
  • Baroreceptors
  • Pituitary blood flow

ASJC Scopus subject areas

  • Physiology

Cite this

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title = "Mechanisms regulating neurohypophysial blood flow and function during isotonic volume expansion",
abstract = "Regional cerebral and neurohypophysial blood flow responses to isotonic extracellular fluid volume expansion were studied in pentobarbital-anesthetized dogs using radiolabeled microspheres. Measurements were made at baseline and after increasing pulmonary capillary wedge pressure by 8 ± 2 mmHg. Plasma arginine vasopressin (AVP) decreased by 50{\%}, and neural lobe blood flow (NLBF) decreased by 47{\%}. Blood flow through median eminence and other brain regions was unchanged. We investigated potential mechanisms responsible for the NLBF changes. Following control vagotomy, AVP concentration increased during the first hour and then returned to control values for hours 2 and 3, whereas NLBF was unchanged for the first hour and fell after 2 and 3 h. Vagus section abolished the decrease in NLBF but not the AVP response to volume expansion. The contribution of left atrial and pulmonary baroreceptors to this response was tested by inflation of a balloon in the left atria to produce a 13 ± 1 mmHg rise in atrial pressure. This led to a 20{\%} reduction in NLBF, a 35{\%} reduction in AVP concentration, and a 270{\%} increase in plasma atrial natriuretic factor (ANF). However, ANF release does not account for the NLBF changes, since intravenous ANF infusion had no effect on NLBF or AVP concentration. These data suggest that the NLBF response to volume expansion is mediated by the vagus with input from multiple cardiopulmonary baroreceptors.",
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T1 - Mechanisms regulating neurohypophysial blood flow and function during isotonic volume expansion

AU - Diringer, M. N.

AU - Wilson, D. A.

AU - Hanley, Daniel F

AU - Wu, Katherine Chih-Ching

AU - Ladenson, Paul W

AU - Traystman, R. J.

PY - 1992

Y1 - 1992

N2 - Regional cerebral and neurohypophysial blood flow responses to isotonic extracellular fluid volume expansion were studied in pentobarbital-anesthetized dogs using radiolabeled microspheres. Measurements were made at baseline and after increasing pulmonary capillary wedge pressure by 8 ± 2 mmHg. Plasma arginine vasopressin (AVP) decreased by 50%, and neural lobe blood flow (NLBF) decreased by 47%. Blood flow through median eminence and other brain regions was unchanged. We investigated potential mechanisms responsible for the NLBF changes. Following control vagotomy, AVP concentration increased during the first hour and then returned to control values for hours 2 and 3, whereas NLBF was unchanged for the first hour and fell after 2 and 3 h. Vagus section abolished the decrease in NLBF but not the AVP response to volume expansion. The contribution of left atrial and pulmonary baroreceptors to this response was tested by inflation of a balloon in the left atria to produce a 13 ± 1 mmHg rise in atrial pressure. This led to a 20% reduction in NLBF, a 35% reduction in AVP concentration, and a 270% increase in plasma atrial natriuretic factor (ANF). However, ANF release does not account for the NLBF changes, since intravenous ANF infusion had no effect on NLBF or AVP concentration. These data suggest that the NLBF response to volume expansion is mediated by the vagus with input from multiple cardiopulmonary baroreceptors.

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