Fluorescence microscopic morphometry of functioning blood vessels and adrenergic nerves in myocardium

The purpose of this study was to quantify the percent volume of actively functioning blood vessels in five dogs subjected to ligation of the left anterior descending artery and to localize catecholamine-containing nerve terminals in the same tissue blocks. Radioactive microspheres were injected to determine the extent of flow reduction in the ischemic zone. After 1 or 3 hr of occlusion, thioflavin-S (0.125 ml/Kg of a 4% solution) was injected intravenously 15 sec prior to removal of the heart. Tissue samples were reacted with paraformaldehyde to visualize catecholamine-containing nerve terminals prior to embedding in paraffin. The percent volume of blood vessels labeled with thioflavin-S was quantitated in tissue sections using a point-counting technique in which a small dot from a video screen was projected through an image-projecting tube and moved by computer control over the image of the fluorescent tissue. In the nonischemic zone, the mean blood flow determined by the microsphere technique was 1.29 ml/min/g +/- 0.48 (SD), and the mean volume percent of thioflavin-labeled vessels was 12.67 +/- 3.30. In the ischemic and border zone areas, there was wide range of flow reduction, and there was a significant correlation between the blood flow measured with microspheres and the percent volume of thioflavin-labeled blood vessels (R = 0.80, P less than 0.001). In the nonischemic zone, both blood vessels and catecholamine-containing nerve terminals were visible; however, in the ischemic zone, few labeled vessels were seen, although nerve terminals were often present.(ABSTRACT TRUNCATED AT 250 WORDS)