Objective: In myocardial ischaemia, slow conducting capsaicin-sensitive C-fibres are activated. Apart from the mediation of pain, Ž . activation of these fibres causes release of various peptides, such as calcitonin gene-related peptide CGRP , which is a potent vasodilator. The aim of this study was to investigate the role of CGRP in the context of myocardial ischaemia in vivo. Methods: The left anterior Ž . descending coronary artery LAD was occluded during 45 min in 27 anaesthetised open-chest pigs. LAD flow, mean arterial pressure Ž . MAP , heart rate, peak d Prdt, arterial and coronary venous concentration of CGRP was measured prior to ischaemia, and during 4 h of reperfusion. The extent of myocardial infarction was measured using staining with triphenyl tetrazolium chloride. Results: Retroinfusion Ž . of CGRP 100 mg into the ischaemic myocardium was associated with a more pronounced hyperaemia, and systemic hypotension, during Ž . early reperfusion. The infarct size in relation to the area at risk was not affected by CGRP or the CGRP antagonist CGRP 8-37 , and averaged 67 " 3%. There were no changes in plasma CGRP levels during ischaemia or reperfusion. Conclusion: Exogenously administered CGRP can cause systemic hypotension and augments postischaemic coronary flow. In this model, no cardioprotective effect of CGRP could be proven. q