| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, Texas, USA
2 Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, Texas, USA; The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
* To whom correspondence should be addressed. E-mail: BenjaminLevine{at}TexasHealth.org.
Women have a greater incidence of orthostatic intolerance than men. We hypothesized that this difference is related to hemodynamic effects on the regulation of cardiac filling rather than to a reduced responsiveness of vascular resistance during orthostatic stress. We constructed Frank-Starling curves from pulmonary capillary wedge pressure (PCWP) and stroke volume (SV) as well as stroke index during lower body negative pressure (LBNP) and rapid saline infusion in 10 healthy, sedentary women (29.6 ± 1.9 yrs, mean ± SE) and 13 control men (25.5 ± 1.4 yrs). Orthostatic tolerance was determined by progressive LBNP to presyncope with continuous hemodynamic monitoring including PCWP and right atrial pressure. We found that LBNP tolerance was significantly lower in females than males (626.8 ± 55.0 vs. 927.7 ± 53.0 mmHg x min, P< 0.01). Women had a steeper maximal slope of their Frank-Starling curves than men whether expressed as SV (12.5 ± 2.0 vs. 7.1 ± 1.5 ml/mmHg, P< 0.05) or normalized as stroke index (6.31 ± 0.8 vs. 4.29 ± 0.6 ml/m2/mmHg, P< 0.05). During progressive LBNP, PCWP dropped quickly at low levels of LBNP, then more slowly and reached a plateau at high levels of LBNP near presyncope in all subjects. At presyncope, SV was 35% and stroke index was 29% lower for the females compared with the males (both P< 0.05). Coincident with the smaller SV, females had higher heart rates (P< 0.05), but similar mean arterial pressures compared with males at the onset of presyncope. Vascular resistance was similar and plasma norepinephrine concentration did not differ between the genders. These results suggest that lower orthostatic tolerance in women is associated with a decreased cardiac filling rather than a reduced responsiveness of vascular resistance during an orthostatic challenge. Thus, cardiac mechanics and the Frank-Starling relationship may be important mechanisms underlying the gender difference in orthostatic tolerance.
This article has been cited by other articles:
|
|
 |
|
  J. S. Floras and S. Mak Muscle sympathetic nerve activity in women and men following acute myocardial infarction: a meaningful difference? Eur. Heart J., July 2, 2009; 30(14): 1692 - 1694. [Full Text] [PDF]
|
|
|
|
 |
|
 Q. Fu, K. Okazaki, S. Shibata, R. P. Shook, T. B. VanGunday, M. M. Galbreath, M. F. Reelick, and B. D. Levine Menstrual cycle effects on sympathetic neural responses to upright tilt J. Physiol., May 1, 2009; 587(9): 2019 - 2031. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. M. Keller, D. A. Low, J. E. Wingo, R. M. Brothers, J. Hastings, S. L. Davis, and C. G. Crandall Acute volume expansion preserves orthostatic tolerance during whole-body heat stress in humans J. Physiol., March 1, 2009; 587(5): 1131 - 1139. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. E. J. Lott, C. Hogeman, M. Herr, M. Bhagat, and L. I. Sinoway Sex differences in limb vasoconstriction responses to increases in transmural pressures Am J Physiol Heart Circ Physiol, January 1, 2009; 296(1): H186 - H194. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Lindenberger, H. Olsen, and T. Lanne Lower capacitance response and capillary fluid absorption in women to defend central blood volume in response to acute hypovolemic circulatory stress Am J Physiol Heart Circ Physiol, August 1, 2008; 295(2): H867 - H873. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. A. Dorfman, B. D. Rosen, M. A. Perhonen, T. Tillery, R. McColl, R. M. Peshock, and B. D. Levine Diastolic suction is impaired by bed rest: MRI tagging studies of diastolic untwisting J Appl Physiol, April 1, 2008; 104(4): 1037 - 1044. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. E. Wilson, C. Tollund, C. C. Yoshiga, E. A. Dawson, P. Nissen, N. H. Secher, and C. G. Crandall Effects of heat and cold stress on central vascular pressure relationships during orthostasis in humans J. Physiol., November 15, 2007; 585(1): 279 - 285. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. C. Tuday and D. E. Berkowitz Microgravity and cardiac atrophy: no sex discrimination J Appl Physiol, July 1, 2007; 103(1): 1 - 2. [Full Text] [PDF]
|
|
|
|
|
|
T. A. Dorfman, B. D. Levine, T. Tillery, R. M. Peshock, J. L. Hastings, S. M. Schneider, B. R. Macias, G. Biolo, and A. R. Hargens Cardiac atrophy in women following bed rest J Appl Physiol, July 1, 2007; 103(1): 8 - 16. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. H. Huxley Sex and the cardiovascular system: the intriguing tale of how women and men regulate cardiovascular function differently Advan Physiol Educ, March 1, 2007; 31(1): 17 - 22. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Lindenberger and T. Lanne Sex-related effects on venous compliance and capillary filtration in the lower limb Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2007; 292(2): R852 - R859. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. P. Kenny, J. E. Murrin, W. S. Journeay, and F. D. Reardon Differences in the postexercise threshold for cutaneous active vasodilation between men and women Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2006; 290(1): R172 - R179. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Cui, S. Durand, B. D. Levine, and C. G. Crandall Effect of skin surface cooling on central venous pressure during orthostatic challenge Am J Physiol Heart Circ Physiol, December 1, 2005; 289(6): H2429 - H2433. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. s. Journeay, F. D. Reardon, N. H. McInnis, and G. P. Kenny Nonthermoregulatory control of cutaneous vascular conductance and sweating during recovery from dynamic exercise in women J Appl Physiol, November 1, 2005; 99(5): 1816 - 1821. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. M. Foley, P. J. Mueller, E. M. Hasser, and C. M. Heesch Hindlimb unloading and female gender attenuate baroreflex-mediated sympathoexcitation Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2005; 289(5): R1440 - R1447. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. R. Meendering, B. N. Torgrimson, B. L. Houghton, J. R. Halliwill, and C. T. Minson Menstrual cycle and sex affect hemodynamic responses to combined orthostatic and heat stress Am J Physiol Heart Circ Physiol, August 1, 2005; 289(2): H631 - H642. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Q. Fu, S. Witkowski, K. Okazaki, and B. D. Levine Effects of gender and hypovolemia on sympathetic neural responses to orthostatic stress Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2005; 289(1): R109 - R116. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. H. Huxley, J. Wang, and S. P. Whitt Sexual dimorphism in the permeability response of coronary microvessels to adenosine Am J Physiol Heart Circ Physiol, April 1, 2005; 288(4): H2006 - H2013. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
