A sensitive in vivo platelet function test in rats based on intravenously injected collagenase.

The transient decrease of the platelet concentration in the flowing blood after intravenous injection of collagenase was used as a measure for the effectiveness of the platelet-vessel wall interactions in rats. The decrease of the concentration in circulating platelets was regarded as an expression of the in vivo platelet function. The influence of acetylsalicylic acid, imidazole, indomethacin, ketanserin, RA 233, and dipyridamole on this test was investigated in anaesthetized rats. All tested drugs showed an effect on the extent of the platelet concentration decrease after the collagenase injection compared to the control values, but no drug was significantly effective. This test could prove to be a valuable tool for testing the efficiency of antithrombotic drugs in vivo.