|Budget Amount *help
¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1991 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1990 : ¥1,100,000 (Direct Cost : ¥1,100,000)
We examined anatomically the hearts, lungs, and great vessels of 269 WKY/NCrj rats at three fetal and three neonatal stages. Severe pulmonary valve thickening was present in 16 and ventricular septal defects with overriding of the aorta in 15 of the 90 near-term fetuses and in 10 and nine, respectively, of the 79 neonates at 2-4 d of age. These abnormalities occurred together (tetralogy of Fallot) in seven of the near-term fetuses and in five of the neonates. A narrow pulmonary outflow tract was present in 55% of the fetuses and in 56% of the neonates. The wall of the pulmonary arterial branch was abnormally thick in 19% of the fetuses and in 26% of the neonates, most of which did not have septal defects. In about 80% of the fetuses, the middle latitudinal muscle bundle of the ventricular septum was not-continuous with the left ventricular free wall, but rather with the right ; after birth, it was discontinuous with both free walls. The heart wag abnormally heavy in 49% of the 79 neona
tes. In about half of the heavy hearts, there were no septal defects or pulmonary valvular and arterial lesions. There were double aortic arches in four and right aortic arches in six of the total WKY fetuses and neonates ; the ductus arteriosus was abnormally small in 47% and the aorta was large in 51% of the nearterm fetuses. This constellation of congenital heart disease is genetic in origin, but altered by hemodynamics late in fetal life.
We examined 78 fetuses on d 21 of gestation (G21) and 83 neonates on d 2 after birth (A2), which were first generation offsping of WKY rats mated with normal Wistar rats (Fl). In addition, we examined six groups of fetuses on d 19 of gestation (Gl9) : 65 Wistar rats, 111 WKY rats, 85 Fl, 100 Fl x Fl, 92Fl x Wistar, and 97 Fl x WKY progeny. These results suggest that cardiovascular anomalies of WKY rati are transmitted as autosomal recessive or incomplete autosomal dominant traits with an incomplete penetrance and variable expressivity or as polygenic traits. Chromosomal analysis of 31 WKY fetuses revealed no abberations specifically related to the development of cardiovascular malformations.
A high-frequency transducer was used to determine the optimal parameters for visualizing the heart in 40 normal Wistar, 15 SHR, and 10 aorta-banded rats. The rats were 5 to 30 weeks old and weighed between 105 and 705 grams. Two-dimensional and M-mode views of the ventricles, atria, valves, and great arteries were obtained by placing the transducer beneath the rats through the left or right parasternal window in either the prone or the right decubitus positions, respectively. Echocardiography is useful for obtaining anatomical evaluation and quantitative measurements in the hearts of the rats.