CAPILLARY DENSITY AND LEUKOCYTE ADHESION IN HAMSTERS WITH HEREDITARY CARDIOMYOPATHY

The aim of this study was to characterize microvascular networks in ch eek pouch of cardiomyopathic Syrian hamster (CM) (Bio 14.6), which is an interesting model of idiopathic cardiomyopathy and congestive heart failure. Microcirculation was visualized by fluorescence microscopy. Diameter and length of arterioles, classified according to centrifugal ordering scheme, were measured. A computational method was arranged t o determine the density of arterioles and capillaries (total vessel le ngth per unit area, cm-l), fractal dimension of capillaries, and the a ssociated Voronoi tesselation. Furthermore, leukocyte adhesion to venu les and arteriolar reactivity to drugs were studied. Increase in the n umber of terminal arterioles and capillary rarefication characterized CM microvasculature compared with that of age-matched controls (58 +/- 7 versus 25 +/- 5 cm(-1), and 128 +/- 15 versus 240 +/- 10 cm(-1), re spectively). Fractal dimension of capillaries was reduced in CM compar ed with controls (1.40 +/- 0.10 versus 1.85 +/- 0.09) and associated w ith increased avascular spaces, as shown by Voronoi tesselation result s. Leukocyte adhesion to venules increased significantly in CM. In CM responsiveness of arterioles to nitric oxide inhibition and propranolo l was slighter but more marked to norepinephrine and angiotensin II co mpared with that of control hamsters. In conclusion, the different geo metry, increased leukocyte adhesion, and altered arterial responsivene ss may contribute to now disturbances in the microcirculation of CM ha msters. (C) 1998 Academic Press.