Particle-Induced Coronary Vasoconstriction in the Rat Heart: Pharmacological Investigation of Underlying Mechanisms.

(the thoracic and cardiovascular surgeon - 1986, 34: 316-325)

Summary: An isolated perfused rat heart preparation has been used in an attempt to define the mechanisms underlying the coronary vasoconstriction associated with the intraarterial infusion of cardioplegic solutions containing contaminant particles. Coronary infusion of commercially available intravenous solutions, compounded to create the St. Thomas cardioplegic solution, resulted in a 40.3±1.9% decline in coronary flow rte at the end of a 20 minute period of infusion. Filtration of the solution through a 0.8 micron filter reduced this decline in flow rate to 23.4±2.3% of its control value. Inclusionof the 5HT2 receptor antagonist ketanserin (1.0 nanomoles/I), in the unfiltered cardioplegic solution, afforded the same protection as filtration. Inclusion of 5HT (0.1 micromole/I) in a filterad cardioplegic solution resulted in a reduction of coronary flow (49.7±1.9%) greater than that seen with the unfiltered solution. Studies with antagonists of the histamine receptor (mepyramine and cimetidine) and agonists and antagonists of adrenergic receptors suggested that, although involved in the control of vascular tone, these receptor siystems are unlikely to be involved in the process of particle-induced vasocontriction. Arguments are presented that 5HT and its receptors may play a critical role and the hypothesis is advanced that particle-induced focal endothelial injury may be the primary lesion in a complex sequence of events leating to induction of transient vasoconstriction.