[Calcitonin gene-related peptide and thrombolysis]

After thrombolytic therapy with urokinase (UK) plasmaimmunoreactive calcitonin gene-related peptide (CGRP-ir) in patients with acute myocardial infarction (AMI) was increased rapidly, and 2 hours after treatment with UK the plasma CGRP-ir reached peak value which was 5 times higher than that before thrombolytic therapy. Fourteen hours after therapy with UK the plasma CGRP-ir gradually decreased to the initial level before treatment. In rat model with abdominal aorta thrombosis induced by FeCl3-injured vascular endothelium, it was found that change in plasma CGRP-ir of the rats after treatment with UK was similar to that of AMI patients, and that administration of CGRP alone had no recanalization effect on the thrombotic blood vessel. However, treatment with CGRP synergically potentiated the UK-induced vascular recanalization in a dose-dependent manner. And antagonist of CGRP (CGRP8-37) significantly attenuated the recanalization action of UK. The results suggest that release of CGRP by tissues could play an endogenous protective role in thrombolytic therapy with UK, and exogenous administration of CGRP might be useful clinically as an assistant of vascular recanalization.