Calcium antagonists and the ischaemic myocardium.

We have investigated whether Ca2+ antagonists reduce the amount of noradrenaline (NA) lost from the myocardium during periods of ischaemia and reperfusion. Hearts obtained from adult, male, normotensive Sprague-Dawley rats were perfused at 37 degrees C before being made globally ischaemic for 15 or 60 min and assayed for catecholamines. Some of these hearts were reperfused. Aerobic perfusion for 90 min failed to cause a significant loss of left ventricular NA. Ischaemia for 15 min followed by reperfusion for 15 min, and ischaemia for 60 min with or without reperfusion caused a significant loss of NA. The loss of NA caused by 15 min ischaemia and reperfusion was abolished or attenuated by verapamil, nifedipine, nitrendipine, nisoldipine and diltiazem.