| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Departments of Physiology and Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75235
Chronic
microgravity may modify adaptations of the leg circulation to
gravitational pressures. We measured resting calf compliance and blood flow with venous occlusion plethysmography, and arterial blood pressure with sphygmomanometry, in seven subjects before, during,
and after spaceflight. Calf vascular resistance equaled mean arterial
pressure divided by calf flow. Compliance equaled the slope of the calf
volume change and venous occlusion pressure relationship for thigh cuff
pressures of 20, 40, 60, and 80 mmHg held for 1, 2, 3, and 4 min,
respectively, with 1-min breaks between occlusions. Calf blood flow
decreased 41% in microgravity (to 1.15 ± 0.16 ml · 100 ml
1 · min1) relative to 1-G supine
conditions (1.94 ± 0.19 ml · 100 ml1 · min1, P = 0.01), and arterial pressure tended to increase (P = 0.05), such that calf vascular resistance doubled in microgravity
(preflight: 43 ± 4 units; in-flight: 83 ± 13 units;
P < 0.001) yet returned to preflight levels after
flight. Calf compliance remained unchanged in microgravity but tended
to increase during the first week postflight (P > 0.2). Calf vasoconstriction in microgravity qualitatively agrees with
the "upright set-point" hypothesis: the circulation seeks
conditions approximating upright posture on Earth. No calf hemodynamic
result exhibited obvious mechanistic implications for postflight
orthostatic intolerance.
weightlessness; gravity; leg; vascular resistance; blood flow; venous compliance
This article has been cited by other articles:
|
|
 |
|
  M. Kooijman, D. H. J. Thijssen, P. C. E. de Groot, M. W. P. Bleeker, H. J. M. van Kuppevelt, D. J. Green, G. A. Rongen, P. Smits, and M. T. E. Hopman Flow-mediated dilatation in the superficial femoral artery is nitric oxide mediated in humans J. Physiol., February 15, 2008; 586(4): 1137 - 1145. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. E. Watenpaugh, D. D. O'Leary, S. M. Schneider, S. M. C. Lee, B. R. Macias, K. Tanaka, R. L. Hughson, and A. R. Hargens Lower body negative pressure exercise plus brief postexercise lower body negative pressure improve post-bed rest orthostatic tolerance J Appl Physiol, December 1, 2007; 103(6): 1964 - 1972. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Gabrielsen and P. Norsk Effect of spaceflight on the subcutaneous venoarteriolar reflex in the human lower leg J Appl Physiol, September 1, 2007; 103(3): 959 - 962. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. M. Baevsky, V. M. Baranov, I. I. Funtova, A. Diedrich, A. V. Pashenko, A. G. Chernikova, J. Drescher, J. Jordan, and J. Tank Autonomic cardiovascular and respiratory control during prolonged spaceflights aboard the International Space Station J Appl Physiol, July 1, 2007; 103(1): 156 - 161. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Norsk, M. Damgaard, L. Petersen, M. Gybel, B. Pump, A. Gabrielsen, and N. J. Christensen Vasorelaxation in Space Hypertension, January 1, 2006; 47(1): 69 - 73. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Hesse, H. Siedler, S. P. Luntz, B. M. Arendt, R. Goerlich, R. Fricker, M. Heer, and W. E. Haefeli Modulation of endothelial and smooth muscle function by bed rest and hypoenergetic, low-fat nutrition J Appl Physiol, December 1, 2005; 99(6): 2196 - 2203. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. J. Mueller, C. M. Foley, and E. M. Hasser Hindlimb unloading alters nitric oxide and autonomic control of resting arterial pressure in conscious rats Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2005; 289(1): R140 - R147. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. W. P. Bleeker, P. C. E. De Groot, F. Poelkens, G. A. Rongen, P. Smits, and M. T. E. Hopman Vascular adaptation to 4 wk of deconditioning by unilateral lower limb suspension Am J Physiol Heart Circ Physiol, April 1, 2005; 288(4): H1747 - H1755. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. W. P. Bleeker, P. C. E. De Groot, J. A. Pawelczyk, M. T. E. Hopman, and B. D. Levine Effects of 18 days of bed rest on leg and arm venous properties J Appl Physiol, March 1, 2004; 96(3): 840 - 847. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Stewart, M. S. Medow, L. D. Montgomery, and K. McLeod Decreased skeletal muscle pump activity in patients with postural tachycardia syndrome and low peripheral blood flow Am J Physiol Heart Circ Physiol, March 1, 2004; 286(3): H1216 - H1222. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Freeman, V. Lirofonis, W. B. Farquhar, and M. Risk Limb venous compliance in patients with idiopathic orthostatic intolerance and postural tachycardia J Appl Physiol, August 1, 2002; 93(2): 636 - 644. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. G. Schrage, C. R. Woodman, and M. H. Laughlin Mechanisms of flow and ACh-induced dilation in rat soleus arterioles are altered by hindlimb unweighting J Appl Physiol, March 1, 2002; 92(3): 901 - 911. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L.-F. Zhang Vascular adaptation to microgravity: what have we learned? J Appl Physiol, December 1, 2001; 91(6): 2415 - 2430. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
