Echocardiography Differentiates Lethally Irradiated Whole-Body From Partial-Body Exposed Rats

Figure 1. Radiation exposure (RE) affects percent survival of whole body (WB) and two leg shielded (2LS) groups. The WB group meets the euthanasia criteria on average by 10 days post-RE, while the 2LS group survives past the thirty-day time point. N = 6-7.

Figure 2. Acute effects of radiation exposure (RE) on cardiac function (8-9 days post exposure). (Top row measurements using echocardiography). (A) Stroke volume significantly decreased in the whole body (WB) irradiated group compared to both baseline and two legs shielded (2LS) group. (B) Cardiac output significantly decreased in the WB compared to the two legs shielded (2LS), but not the baseline and group. (Bottom row measurements using MRI). (C) While relative stroke volume in the WB was significantly lower than baseline, it was not different from 2LS. (D) Relative cardiac output was significantly reduced in the WB group. N = 5–12, *p < 0.05, **p < 0.01, ***p < 0.001.

Figure 3. Acute effects of radiation exposure (RE) on pulmonary artery function. (A,B) Six days post RE, the velocity time integral (VTI) and pulmonary artery acceleration time (PAAT) were significantly decreased in the whole body (WB) irradiated group compared to baseline but only the PAAT was different from the 2-leg shielded (2LS) group. (C,D) Ten days post RE, VTI and PAAT were significantly decreased in the WB compared to baseline and 2LS groups. N = 4–7, *p < 0.05, **p < 0.01.

Figure 4. Radiation exposure (RE) of the whole body (WB), but not partial body (2LS), alters red blood cell rheology. (A,B) At 9 days post exposure, viscosity was measured at two shear rates 45s−1 and 25s−1, (venous and arterial circulation) and were significantly lower in the WB compared to baseline and 2LS animals, but not between the 2LS and baseline. (C) Percentage of dense red blood cells, a measure of “useless” erythrocytes, increased significantly in the WB compared to both baseline and 2LS, but 2LS was not different from baseline. (D) Free hemoglobin (total - cellular) adjusted for reduced erythropoiesis by dividing by total Hb was significantly higher in WB compared to baseline. N = 3–5, *p < 0.05, **p < 0.01, ****p < 0.0001.

Figure 5. Radiation exposure (RE) affects rheological values. (A) At 9 days post exposure percent of hematocrit was significantly lower in whole body (WB) irradiated compared to baseline and two leg shielded (2LS) animals. The 2LS hematocrit was also significantly lower than baseline. (B,C) Red blood cell membrane deformability index and Reticulocyte hemoglobin content (CHr), a measure of the amount of hemoglobin in reticulocytes, both demonstrated a significant decline in WB compared to 2LS. N = 3–5, **p < 0.01, ***p < 0.001, ****p < 0.0001.