A Study On Cardiovascular Effects And Underlying Mechanisms Of Infrasound

Infrasound existing widely in nature has already aroused the interests of environmental and military scientists in many countries for its characters of less attenuation during propagation, inaudibility and broad harm in some cases. In the studies of environmental hygienics, it is indicated that infrasound pervades the circumstances of industry, architecture and traffic, which is one of the most important factors of environmental pollution. Military scientists believed that infrasound could be produced by airplane, cannon, missile and radar. Furthermore, more and more attention has been paying to the roles of the infrasound weapons (as a kind of new concept weapon) for the future wars.The primary effect of infrasound on humans appears to be annoyance. To achieve a given amount of annoyance, low frequencies were found to require greater sound pressurethan higher frequencies; Small changes in sound pressure level could then possibly cause significantly large changes in annoyance in the infrasound region. There is no agreement about the biological activity of infrasound. Reported effects include those on the inner ear, vertigo, imbalance, etc;intolerable sensations, incapacitation, disorientation, nausea, vomiting, and bowel spasm; and resonance in inner organs, such as the heart.With the development of science and technology, man-made infrasonic sources increase largely and the potential harm of the infrasound to human is increasing, so that some countries begin to take serious looks at the studies on infrasonic bioeffects, especially on human. The basic principle of the infrasound exposed to organism is that infrasound causes biological resonance and a series of bioeffects directly. Infrasound exposure results in damnification to the whole organism, organs, tissues and cells, the damnification extent depends on the parameters of infrasound. Cardiovascular system is relatively important in the studies of infrasonic bioeffects, but the mechanisms have not been still clear, and further investigation should be carried out. In China, there are some reports only about changes of blood pressure and pulse caused by infrasound, but the systematic study on cardiovascular infrasonic bioeffects is absent. Therefore, it is important to develop the investigation for theory and praxis. Our experiments established the bases for studies of infrasonic bioeffects and its defence. This thesis is composed of three parts:Part I : The Changes of Heart Rate and Blood Pressureof the Rats Exposed to the Infrasound with Different Parameters.Purpose: To observe and explore the changes of heart rate (HR) and mean arterial pressure (MAP) of the rats exposed to infrasound.Methods: By intubatton to jugular vein and femoral of rats exposed to the infrasound with different parameters, the changes of HR and BP were observed through RM-6280 physiological record and analysis instrument.Results: 1. Rats exposed to the infrasound of 8Hz 90dB: The HR of the rats in 1d group increased significantly while the HR of the rats in 7, 14, 21 and 28d groups did not increase significantly. Rats exposed to the infrasound of 8Hz 130dB: The HR of the rats in 1d group increased significantly, but there was no significant change of the HR in 14, 21 and 28d groups. Compared with the groups exposed to the infrasound of 8Hz, 90dB, the increase of HR in 1d group was more significant.2. Rat exposed to the infrasound of 8Hz 90dB: The left ventricular systolic pressure (LVSP) of the rats in 7d group increased significantly, whereas LVSP in 1,14,21and 28d groups furthre increased. Rats exposed to the infrasound of 8Hz, 130dB: The LVSP of the rats in 1d group did not change significantly , while LVSP in 7d group increased significantly and LVSP in 14, 21 and 28d groups further increased. Compared with the groups exposed to the infrasound of 8Hz, 90dB, the LVSP in 7, 14 , 21and 28d groups increased significantly and LVSP in1d groups increased mostly.3. Rats exposed to the infrasound of 8Hz 90dB: The leftventricle diastolic pressure (LVDP) of the rat...