Inability of chronic chemical sympathectomy to induce coronary collateral growth or development: studies in the rat heart in vivo.

The influence of chronic chemical sympathectomy on the extent of coronary collateral flow delivered to a zone of regional ischaemia following an acute coronary artery occlusion was examined in the rat. Male rats were randomly assigned to either 6-hydroxydopamine treated or vehicle treated groups (n = 20 in each group). Drug treated animals were injected with 6-hydroxydopamine intravenously as follows: day 1, 10 mg.kg-1; day 2, 50 mg.kg-1; days 7, 8, 14, 15, 21, 28, 35 and 42, 100 mg.kg-1. Control animals were injected in a similar manner with vehicle solution. On day 43, animals were anaesthetised, and their hearts were excised and perfused in the Langendorff mode at a perfusion pressure of 10 kPa. After 5 min the left main coronary artery was ligated and after a further 5 min, 153Gd labelled microspheres (10 microCi, 15 microns diameter) were infused via a side arm on the aortic cannula. This was followed within 3 min by the infusion of 3H-desmethylimipramine (5 microCi) via the same route. Disulphine blue dye was injected via the side arm within 1 min of the desmethylimipramine injection so as to delineate the perfused from the ischaemic region. The hearts were frozen in liquid nitrogen and freeze dried. The dried hearts were separated into ischaemic and non-ischaemic tissue on the basis of the blue dye coloration. The weighed samples were assessed for gamma and beta activity and the ratio of radioactive counts.g-1 in the ischaemic tissue to that of the non-ischaemic tissue was taken as an index of relative coronary collateral flow.(ABSTRACT TRUNCATED AT 250 WORDS)