Postural cardiovascular reflexes: Comparison of responses of forearm and calf resistance vessels

Louis Kofi Essandoh, D. A. Duprez, J. T. Shepherd

Research output: Contribution to journalArticle

Abstract

Simultaneous measurements were made of changes in vascular resistance in the forearm and calf in response to moving from supine to sitting or to head-down tilt. The subjects were healthy male volunteers, 21-63 yr. Blood flows were measured by venous occlusion plethysmography using mercury-in-Silastic strain-gauges. The gauges were maintained at the same level relative to the heart during the postural changes. Arterial blood pressure was measured by auscultation; heart rate was counted from the plethysmograms. Changing from supine to sitting caused a decrease in forearm blood flow from 4.13 ± 0.14 to 2.16 ± 0.19 ml·100 ml-1·min-1. Corresponding calf flows were 4.21 ± 0.32 and 4.40 ± 0.59 ml·100 ml-1·min-1. There was no change in mean arterial blood pressure, and heart rate increased by 8.0 ± 1.5 beats/min. Arrest of the circulation of both legs with occlusion cuffs on the thighs before sitting, to prevent pooling of blood in them, reduced the degree of forearm vasoconstriction. Neck suction (40 Torr) during sitting, to oppose the decrease in transmural pressure at the carotid sinuses, inhibited the vasoconstriction. During a 30°head-down tilt, there was a dilatation of forearm but not of calf resistance vessels. A Valsalva maneuver caused a similar constriction of both vascular beds. Thus, when changes in vascular resistance in forearm and calf are compared, the major reflex adjustments to changes in posture take place in the forearm.

Original languageEnglish (US)
Pages (from-to)1801-1805
Number of pages5
JournalJournal of Applied Physiology
Volume63
Issue number5
StatePublished - 1987
Externally publishedYes

Fingerprint

Forearm
Reflex
Arterial Pressure
Vasoconstriction
Vascular Resistance
Heart Rate
Head-Down Tilt
Social Adjustment
Auscultation
Valsalva Maneuver
Carotid Sinus
Plethysmography
Suction
Thigh
Mercury
Posture
Constriction
Blood Vessels
Dilatation
Leg

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Postural cardiovascular reflexes : Comparison of responses of forearm and calf resistance vessels. / Essandoh, Louis Kofi; Duprez, D. A.; Shepherd, J. T.

In: Journal of Applied Physiology, Vol. 63, No. 5, 1987, p. 1801-1805.

Research output: Contribution to journalArticle

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