title: Acute circulatory collapse caused by platelet-activating factor (PAF-acether) in dogs.
abstract: Synthetic platelet-activating factor (PAF-acether) was shown to act as a shock inducer when a dose of 9 or 36 nmol . kg-1 was injected i.v. into dogs anesthetized with 30 mg . kg-1 i.v. sodium pentobarbitone. Nine nmol . kg-1 PAF-acether caused portal vein and pulmonary artery hypertension but only transiently; blood TXB2 and 6 keto PGF1 alpha levels rose; there was a lasting fall of 77% in systemic blood pressure, cardiac output fell by 86%, heart rate by 17%, plasma volume by 43%, and femoral artery blood flow by 66%, whereas the hematocrit rose by 33%. A dose of 36 nmol . kg-1 PAF-acether reduced coronary artery blood flow by 56%, diminished myocardial O2 consumption, raised O2 extraction and caused metabolic acidosis leading to death in 2 out of 7 animals. All these changes displayed the typical features of common acute circulatory collapse with distributive and hypovolemic etiologies, suggesting that PAF-acether might be an endogenous mediator in the early and late stages of shock.
mesh_terms: D015121:6-Ketoprostaglandin F1 alpha / Q000097:blood; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D004562:Electrocardiography; D004731:Endotoxins / Q000633:toxicity; D006321:Heart / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D010972:Platelet Activating Factor / Q000633:toxicity*; D012769:Shock / Q000139:chemically induced*; D013929:Thromboxane B2 / Q000097:blood
chemical_list: D004731:Endotoxins; D010972:Platelet Activating Factor; D013929:Thromboxane B2; D015121:6-Ketoprostaglandin F1 alpha