EXPOSURE-TIME DEPENDENCE OF THE THRESHOLD FOR ULTRASONICALLY INDUCED MURINE LUNG HEMORRHAGE

Although the extent of suprathreshold damage to murine lung that resul ts from exposure to pulsed ultrasound increases with time, the thresho ld level for lung hemorrhage is relatively insensitive to total exposu re time, Adult mice were exposed for 20 s and 3 min to 2.3-MHz ultraso und (10-mu s pulses, 100-Hz pulse repetition frequency) at peak positi ve pressures ranging up to 3 MPa, Threshold pressures for the two expo sure times, 1.6 MPa and 1.4 MPa, respectively, are the same within the statistical significance of the measurements.