Central hemodynamics in a baboon model during microgravity induced by parabolic flight

• Published in: Advances in space research Vol. 14; no. 8; pp. 349 - 358
• Main Authors: Latham, R.D., Fanton, J.W., Vernalis, M.N., Gaffney, F.A., Crisman, R.P.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.1994
• Subjects: Animals; Blood Volume - drug effects; Cardiovascular Physiological Phenomena; Central Venous Pressure - physiology; Furosemide - pharmacology; Hemodynamics - physiology; Male; Papio - physiology; Sodium Chloride - pharmacology; Space Flight; Space life sciences; Supine Position; Weightlessness; NASA Discipline Cardiopulmonary; NASA Discipline Number 00-00; NASA Program Flight; NASA Program Space Physiology and Countermeasures; NASA Discipline Number 14-10; Non-NASA Center
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/0273-1177(94)90422-7

We developed a chronically instrumented nonhuman primate model (baboon) to evaluate the central cardiovascular responses to transient microgravity induced by parabolic flight. Instrumentation provided simultaneous recording of high fidelity (Ao) and pulmonary artery (PA) pressures, right and left ventricular and atrial pressures, Ao and PA blood flow velocities and vessel dimensions, ECG and pleural pressures. Four daily flights in 1991 and five in 1992 were flown with forty parabola per flight. Animals flown in 1991 were not controlled for volume status. Animals flown in 1992 were studied in one of three conditions: 1) volume depleted by furosemide (DH), 2) volume expanded by saline infusion (VE), and 3) euvolemic (EU, no intervention, used for echo only). Mean right atrial pressures (RAP) during 1991 flights had a variable early microgravity response: increases in n=3 and decrease in n=3 (supine) and increases in n=5, decreases in n=2 (upright). In 1992 flights, DH, upright and supine, changed −10 ± 4.1 mmHg, −3.2 ± 2.2 mmHg, respectively (p<.05) compared to the pull-up phase. In contrast, VE changed (from pull-up to microgravity) +13 ± 1.5 mmHg and +4.25 ± 2.9 mmHg (upright and supine, respectively, p <.05). EU increased with microgravity +6.9 ± .9 mmHg (upright only). LAP responses were similar, but more variable. Finally, heart chamber areas paralleled pressure changes. Thus, right and left heart filling pressure changes with sudden entry into microgravity conditions were dependent on initial circulatory volume status and somewhat modified by position (supine vs upright).