Coronary and systemic 6-ketoprostaglandin F1 alpha and thromboxane B2 during myocardial ischemia in dog.

The left anterior descending coronary artery (LAD) of five dogs was ligated, and blood was withdrawn from the great cardiac vein, left marginal cardiac vein, femoral vein, and aorta. After ligation, immunoreactive 6-ketoprostaglandin (PG) F1 alpha rose from less than 0.1 to a mean value of 1.2 pmol/ml plasma in the great cardiac vein (GCV) and 0.88 pmol/ml in the left marginal vein, with no change in peripheral circulation. Immunoreactive thromboxane (TX) B2 remained below 0.075 pmol/ml throughout the experiments. LAD of 11 dogs was stenosed 60-80% with consequent cyclical reductions in blood flow. 6-Keto-PGF1 alpha in GCV rose in seven dogs (range 0.5-2.2 pmol/ml) and remained unchanged in four. No change was observed in peripheral plasma levels of 6-keto-PGF1 alpha. In these experimental conditions TXB2 remained below 0.075 pmol/ml. Lactate concentrations rose in both experimental conditions in GCV but not in peripheral circulation or in the left marginal vein. This study confirms a link between cardiac ischemia and increased coronary prostacyclin release, but we were unable to detect a similar correlation with TXB2 in plasma.