MYOCARDIAL CAPILLARY DENSITY AND MUSCLE-FIBER SIZE IN RATS BORN AND RAISED AT SIMULATED HIGH-ALTITUDE

  • 1 January 1979
    • journal article
    • research article
    • Vol. 60  (2) , 225-230
Abstract
Rats were born in a hypobaric chamber at a pressure of 500 mmHg and kept there at 460 mmHg for 5, 9 or 13 wk. The myocardial capillary bed was labeled by perfusion with India ink. The density of myocardial capillaries and the area of cross-section of myofibers was estimated from histological sections. In the left ventricle there was a steady reduction in capillary density with increasing age which was similar in test and control rats. There was also an increase in myofiber size which was similar in test and controls. Hypoxia did not induce capillary proliferation or a reduction in myofiber diameter in the left ventricle and this is reflected in a constant capillary:fiber ratio. In the right ventricle, ventricular hypertrophy in the hypoxic rats induced a striking reduction in capillary density due to a 2-fold increase in myofiber size. There was some degree of capillary proliferation, probably a consequence of hypertrophy rather than the direct influence of hypoxia.