CALCITONIN-GENE-RELATED PEPTIDE IN MYOCARDIAL-ISCHEMIA AND REPERFUSION IN THE PIG

Objective: In myocardial ischaemia, slow conducting capsaicin-sensitiv e C-fibres are activated. Apart from the mediation of pain, activation of these fibres causes release of various peptides, such as calcitoni n 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 my ocardial ischaemia in vivo. Methods: The left anterior descending coro nary artery (LAD) was occluded during 45 min in 27 anaesthetised open- chest pigs. LAD flow, mean arterial pressure (MAP), heart rate, peak d P/dt, arterial and coronary venous concentration of CGRP was measured prior to ischaemia, and during 4 h of reperfusion. The extent of myoca rdial infarction was measured using staining with triphenyl tetrazoliu m chloride. Results: Retroinfusion of CGRP(100 mu g) into the ischaemi c myocardium was associated with a more pronounced hyperaemia, and sys temic hypotension, during early reperfusion. The infarct size in relat ion to the area at risk was not affected by CGRP or the CGRP antagonis t CGRP(8-37), and averaged 67 +/- 3%. There were no changes in plasma CGRP levels during ischaemia or reperfusion. Conclusion: Exogenously a dministered CGRP can cause systemic hypotension and augments postischa emic coronary flow. In this model, no cardioprotective effect of CGRP could be proven. (C) 1998 Elsevier Science B.V. All rights reserved.