Evidence for increased cardiac compliance during exposure to simulated microgravity

Steven C. Koenig, Victor A. Convertino, John W. Fanton, Craig A. Reister, F. Andrew Gaffney, David Ludwig, Vladimir P. Krotov, Eugene V. Trambovetsky, Rickey D. Latham

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

We measured hemodynamic responses during 4 days of head-down tilt (HDT) and during graded lower body negative pressure (LBNP) in invasively instrumented rhesus monkeys to test the hypotheses that exposure to simulated microgravity increases cardiac compliance and that decreased stroke volume, cardiac output, and orthostatic tolerance are associated with reduced left ventricular peak dP/dt. Six monkeys underwent two 4-day (96 h) experimental conditions separated by 9 days of ambulatory activities in a crossover counterbalance design: 1) continuous exposure to 10°HDT and 2) ~12-14 h per day of 80°head-up tilt and 10-12 h supine (control condition). Each animal underwent measurements of central venous pressure (CVP), left ventricular and aortic pressures, stroke volume, esophageal pressure (EsP), plasma volume, α1- and β1-adrenergic responsiveness, and tolerance to LBNP. HDT induced a hypovolemic and hypoadrenergic state with reduced LBNP tolerance compared with the control condition. Decreased LBNP tolerance with HDT was associated with reduced stroke volume, cardiac output, and peak dP/dt. Compared with the control condition, a 34% reduction in CVP (P = 0.010) and no change in left ventricular end-diastolic area during HDT was associated with increased ventricular compliance (P = 0.0053). Increased cardiac compliance could not be explained by reduced intrathoracic pressure since EsP was unaltered by HDT. Our data provide the first direct evidence that increased cardiac compliance was associated with headward fluid shifts similar to those induced by exposure to spaceflight and that reduced orthostatic tolerance was associated with lower cardiac contractility.

Original languageEnglish
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume275
Issue number4 44-4
StatePublished - Oct 1 1998
Externally publishedYes

Fingerprint

Head-Down Tilt
Weightlessness
Lower Body Negative Pressure
Compliance
Stroke Volume
Central Venous Pressure
Pressure
Cardiac Output
Fluid Shifts
Space Flight
Hypovolemia
Plasma Volume
Ventricular Pressure
Macaca mulatta
Adrenergic Agents
Cross-Over Studies
Haplorhini
Arterial Pressure
Hemodynamics

Keywords

  • Adrenergic function
  • Blood pressure
  • Central venous pressure
  • Head-down tilt

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

Koenig, S. C., Convertino, V. A., Fanton, J. W., Reister, C. A., Gaffney, F. A., Ludwig, D., ... Latham, R. D. (1998). Evidence for increased cardiac compliance during exposure to simulated microgravity. American Journal of Physiology - Regulatory Integrative and Comparative Physiology, 275(4 44-4).

Evidence for increased cardiac compliance during exposure to simulated microgravity. / Koenig, Steven C.; Convertino, Victor A.; Fanton, John W.; Reister, Craig A.; Gaffney, F. Andrew; Ludwig, David; Krotov, Vladimir P.; Trambovetsky, Eugene V.; Latham, Rickey D.

In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 275, No. 4 44-4, 01.10.1998.

Research output: Contribution to journalArticle

Koenig, SC, Convertino, VA, Fanton, JW, Reister, CA, Gaffney, FA, Ludwig, D, Krotov, VP, Trambovetsky, EV & Latham, RD 1998, 'Evidence for increased cardiac compliance during exposure to simulated microgravity', American Journal of Physiology - Regulatory Integrative and Comparative Physiology, vol. 275, no. 4 44-4.
Koenig, Steven C. ; Convertino, Victor A. ; Fanton, John W. ; Reister, Craig A. ; Gaffney, F. Andrew ; Ludwig, David ; Krotov, Vladimir P. ; Trambovetsky, Eugene V. ; Latham, Rickey D. / Evidence for increased cardiac compliance during exposure to simulated microgravity. In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology. 1998 ; Vol. 275, No. 4 44-4.
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