title: Geometry of capillary networks in volume overloaded rat heart.
abstract: Volume overload cardiac hypertrophy was induced in male Sprague-Dawley rats by experimental aortocaval fistula. This procedure resulted in considerable increases in left ventricular mass (70%) by 21-23 days. Our objective was to study the effect of volume overload on the geometry of coronary capillaries in the left ventricular midmyocardium. Tissue sections were stained according to a protocol that distinguished arteriolar (AC) and venular (VC) capillary regions by color. Morphometric data were then collected and compared between AC and VC regions. In sham-operated controls (CON; n = 8), the tissue area (capillary domain) supplied by a single capillary decreased from AC to VC regions (AC = 505 +/- 5 microns 2: VC = 452 +/- 7 microns 2; P less than 0.01; mean +/- SE). In volume overloaded hearts (VOL; n = 8), only VC domain areas were reduced from control values (P less than 0.01) and the differences between AC and VC regions were preserved (AC = 480 +/- 5 microns 2; VC = 395 +/- 6 microns 2; P less than 0.01). Minimal capillary length was significantly longer in volume overloaded hearts (VOL = 723 +/- 18; CON = 581 +/- 20 microns; P less than 0.01). In the control group, AC segment length was longer than VC segment length (AC = 93 +/- 2 microns: VC = 74 +/- 2 microns; P less than 0.01). In volume overload, AC segment length was also longer than VC segment length, but the divergence between AC and VC regions was increased (AC = 108 +/- 3 microns; VC = 71 +/- 2 microns; P less than 0.01). These changes in capillary geometry may be secondary to specific changes in the arrangement and dimension of myocytes in the left ventricular wall following volume overload hypertrophy.
authors.affiliation: Department of Physiology, Faculty of Medicine, University of Ottawa, Ontario, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Batra
authors.forename: K
authors.initials: K
authors.lastname: Rakusan
mesh_terms: D000818:Animals; D002196:Capillaries / Q000503:physiopathology*; D002306:Cardiac Volume; D006332:Cardiomegaly / Q000503:physiopathology*; D008297:Male; D008433:Mathematics; D008833:Microcirculation; D051381:Rats; D011919:Rats, Inbred Strains