Coronary Flow and Myocardial Biochemical Responses to High Sustained +Gz Acceleration.
TEXAS UNIV MEDICAL BRANCH AT GALVESTON MARINE BIOMEDICAL INST
Pagination or Media Count:
In order to determine directly the myocardial response to Gz acceleration, miniature swine were used as the experimental subjects. All of the unanesthetized instrumented subjects were exposed to multiple Gz acceleration levels for 60-120 seconds 3, 5, 7, 9, 11 Gz on the USAF School of Aerospace Medicine human centrifuge. Other subjects were exposed to a single acceleration level 9 Gz for 120 seconds and the hearts removed for biochemical analyses 1-2 hours later. Mitochondria and a lysosomal fraction were isolated from the left ventricle of all animals. Left circumflex coronary artery flow LCCF, heart rate HR, left ventricular pressure LVP, and the rate of rise of LVP P were measured in the instrumental animals. LVP and HR increased at all levels of acceleration studied while P increased initially but would decline later. LCCF decreased at all levels of acceleration stress. The mitochondrial ADPO ratio and the RCIRespiratory Control Index were unchanged but the QO2Oxygen uptake and calcium uptake were increased at 9 Gz. Free acid phosphatase increased at the same level of acceleration.
- Stress Physiology