title: Inhibition of hypoxic pulmonary vasoconstriction by dipyridamole is not platelet mediated.
abstract: Dipyridamole, which is known to alter platelet function, has also been shown to reduce hypoxic pulmonary vasoconstriction. This latter effect could result from dipyridamole either acting on a platelet-mediated system, or acting directly on pulmonary vascular smooth muscle. To investigate these two possibilities, normal dogs were compared with dogs rendered thrombocytopenic by a platelet antiserum. Compared with the hypoxic pressor response before drug treatment, the hypoxic response following dipyridamole was only 32% as great in the normal dogs and only 38% as great in the thrombocytopenic dogs. Thus, dipyridamole was no less effective in reducing the hypoxic pressor response in the virtual absence of platelets. This supports a direct effect of dipyridamole on pulmonary vascular smooth muscle, which could be mediated by an increase in adenosine levels.
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000276:immunology / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects; D004176:Dipyridamole / Q000494:pharmacology*; D004285:Dogs; D005260:Female; D000860:Hypoxia / Q000150:complications / Q000503:physiopathology*; D007106:Immune Sera / Q000494:pharmacology; D008168:Lung / Q000098:blood supply* / Q000187:drug effects; D008297:Male; D013921:Thrombocytopenia / Q000150:complications / Q000503:physiopathology; D014655:Vascular Resistance / Q000187:drug effects*
chemical_list: D007106:Immune Sera; D004176:Dipyridamole