Proliferative activity of myocardial capillary wall cells in dipyridamole--treated rats.

The hearts of rats treated with dipyridamole were studied by light microscope autoradiography and measurement of tissue radioactivity after intravenous injection of 3H-thymidine. Total tissue radioactivity was significantly increased in the hearts of the dipyridamole-treated animals. Only capillary wall cells were labelled in the autoradiograms. The observations indicate a proliferation of capillary wall cells, suggesting a neoformation of myocardial capillaries during dipyridamole treatment.