Effect of spaceflight on the subcutaneous venoarteriolar reflex in the human lower leg.

نویسندگان

  • Anders Gabrielsen
  • Peter Norsk
چکیده

Whenever the legs are lowered in humans, a venoarteriolar reflex is activated by the hydrostatic distension of the venules. Through local axon reflexes, the adjacent arterioles are contracted to decrease blood flow and prevent formation of edema. Because the venoarteriolar reflex is activated by gravity, we tested the hypothesis that long-term weightlessness would attenuate it. The reduction in subcutaneous blood flow was measured by the (133)Xe washout technique just proximal to the ankle joint in dependent lower legs of eight supine astronauts, where the knee joint was passively bent by 90 degrees . The measurements were conducted before spaceflight and 3-6 h on landing following 4-6.5 mo in space. Activation of the venoarteriolar reflex reduced subcutaneous blood flow by 37 +/- 9% (P = 0.016) before flight and by 64 +/- 8% (P < 0.001) following landing with no statistical significant difference between the two reductions (P = 0.062). Therefore, our results show that the venoarteriolar reflex is not attenuated by weightlessness and therefore does not need the everyday stimulus of gravity to maintain efficiency.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Sympathetic reflex control of subcutaneous blood flow in tetraplegic man during postural changes.

1. The effect of head-up tilt upon subcutaneous blood flow in the distal arm and leg was studied in 12 patients with complete traumatic spinal cord transection at the cervical level. 2. Blood flow was measured by the local 133Xe washout technique. 3. Leg lowering induced a 47% decrease in blood flow in the distal leg. During head-up tilt (45 degrees) blood flow in the leg decreased by 48%. In t...

متن کامل

Effects of 14 days of head-down tilt bed rest on cutaneous vasoconstrictor responses in humans.

This study tested the hypothesis that head-down tilt bed rest (HDBR) reduces adrenergic and nonadrenergic cutaneous vasoconstrictor responsiveness. Additionally, an exercise countermeasure group was included to identify whether exercise during bed rest might counteract any vasoconstrictor deficits that arose during HDBR. Twenty-two subjects underwent 14 days of strict 6 degrees HDBR. Eight of t...

متن کامل

Effects of Space Flight on the Chemical Constituents and Anti-Inflammatory Activity of Licorice (Glycyrrhiza uralensis Fisch)

   Licorice, the oldest Chinese traditional medicine, is widely used in the treatment of human diseases. Due to the deficiency of wild resource, selecting and breeding becomes a key issue to expanding the supply of licorice. Spaceflight technology will become a new method for medicinal plants. The aim of this study was to investigate the effect of spaceflight on the components and anti-inflamma...

متن کامل

Effects of Space Flight on the Chemical Constituents and Anti-Inflammatory Activity of Licorice (Glycyrrhiza uralensis Fisch)

   Licorice, the oldest Chinese traditional medicine, is widely used in the treatment of human diseases. Due to the deficiency of wild resource, selecting and breeding becomes a key issue to expanding the supply of licorice. Spaceflight technology will become a new method for medicinal plants. The aim of this study was to investigate the effect of spaceflight on the components and anti-inflamma...

متن کامل

Abnormal baroreceptor-mediated vasodilation of the peripheral circulation in congestive heart failure secondary to idiopathic dilated cardiomyopathy.

BACKGROUND Peripheral edema is a major clinical problem in congestive heart failure (CHF). The function of the edema-protective baroreceptor-mediated and local nervous vasoconstrictor reflexes of the lower leg during orthostasis in moderate and severe CHF has largely been unexplored. METHODS AND RESULTS Baroreceptor-mediated and local nervous regulation of subcutaneous blood flow of the lower...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Journal of applied physiology

دوره 103 3  شماره 

صفحات  -

تاریخ انتشار 2007