Abstract
Erythrol tetranitrate and mannitol hexanitrate,† since their introduction by Bradbury, 1 have been used to some extent in the prophylactic treatment of patients with angina pectoris; and glycerol trinitrate has received extensive study both experimentally 2 and clinically. 3 This study was undertaken to determine the comparative effects of these 3 drugs on the coronary flow through the isolated rabbit heart.
Method. A modified Langendorf preparation of young and vigorous rabbit hearts was used. The hearts were perfused with Locke' solution containing 1% dog serum, 4 and 0.1% glycine 5 and adjusted to a pH of 7.4. A constant perfusion pressure of 0 cm of water and a constant temperature of 32°C were maintained the experiment. The effects of solutions (a) of 40% erythrol tetranitrate and (b) of glycerol trinitrate in glycerine were compared to those produced by a fine suspension of 40% mannital hexanitrate† in glycerine. Since there was no sharp drop in the coronary flow after the addition of the suspension it was believed that there was no demonstrable plugging of the capillaries. One milliliter of each of these solutions was injected over a period of 3 minutes into the perfusion fluid just above the heart. Only 3 drug tests were made on each heart; however, glycerine controls were run at the beginning and end of each experiment (Fig. 1). Since the activity of the heart and the rate of coronary flow gradually decreased both during these experiments and during control runs in which no drug was added, a base line was drawn along this fall. Comparative values for the 3 drugs were obtained by estimating with a planimeter the area of the increase above the base line following each drug.
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