AJP - Cell Physiology, Vol 252, Issue 1 C97-104, Copyright © 1987 by American Physiological Society
Cardiac hypertrophy in chick embryos induced by hypothermia
C. Boehm, T. R. Johnson, J. D. Caston and R. J. Przybylski
A decrease in incubation temperature from 38 to 32 degrees C elicits a
decrease in chicken embyro size and weight with concomitant heart
enlargement if done after day 10 of incubation. When assayed at day 18 of
incubation with the hypothermia started on day 11 or 14, evidence is
presented that the heart enlargement is an hypertrophy with no detectable
hyperplasia. Supporting data are presented for various physical parameters
showing increases in heart wet and dry weight, volume, area, wall
thickness, and cell size. There was little difference in DNA content and
nuclear [3H]thymidine labeling index between hearts of control and
hypothermic embryos. Hearts of hypothermic embryos showed a slight increase
in water content and considerable increases in RNA, protein, and glycogen
content per unit DNA. The average size of polysomes isolated from
hypothermic hearts was larger than that of polysomes isolated from
controls. Microscopic studies showed no obvious increase in amount of
capillary beds, connective tissue, and myocardial cells. Annulate lamellae
were found only in myocardial cells of hypothermic embryos in sparse
amounts and low frequency but always associated with large deposits of
glycogen.
