Capillarisation of the myocardium of lama (lama glama)

The heart of 12 adult lamas, one female and 11 males, 2-7 years of age, was studied gross-anatomically (absolute and relative heart weight) and micros copic-anatomically (left and right ventricular wall, left auricle). Compari ng the 9 younger animals (2-3 years old) with the 3 older lamas (5-7 years old) a significant increase of the absolute heart weight and of the number of capillaries per mm(2) and a significant decrease of the intercapillary d istance in the left ventricular wall was found. This results in an increase of capillarity in the studied heart regions ( 5.5 % compared to 6.9 %). Th e simultaneous increase of the capillary-to-myocyte-ratios from 0.9 to 1.1 shows a significant correlation to the cross-sectional area of the myocytes (r = 0.79) and an also significant but negative correlation to the number of myocytes per mm2 (r = - 0.82). In both groups the cross-sectional area o f the myocytes and their diameter differs significantly in the three region s of the heart (left ventricular wall - 214 mu m2 resp. 17.5 mum; right ven tricular wall -156 mum(2) resp. 15.5 mum: left auricle - 96 mum(2) resp. 11 .5 mum). It is to be supposed, that the morphological conditions of the car diac vascular supply of lamas living in an altitude of 4000 m are improving with age.