title: Coronary vascular responsiveness to 5-hydroxytryptamine before and after infusion of hyperkalemic crystalloid cardioplegic solution in the rat heart. Possible evidence of endothelial damage.
abstract: Using the isolated, Langendorff-perfused rat heart (n = 8 per group), we have studied the effects of 5-hydroxytryptamine and papaverine on coronary flow before and after a 30-minute infusion of hypothermic (20 degrees C), nonoxygenated cardioplegic solution containing potassium in a concentration of either 25 or 40 mmol/L. Before infusion of the 25 mmol/L potassium cardioplegic solution, both 5-hydroxytryptamine (1 x 10(-7) mol/L) and papaverine (5 x 10(-6) mol/L) caused similar increases in flow (+21.2% +/- 1.6% and +22.8% +/- 1.6%, respectively). After cardioplegia, the vasodilatory response to 5-hydroxytryptamine was completely lost and a slight vasoconstriction was observed (-0.2% +/- 1.2%). However, there was no significant change in the response to papaverine, which maintained a +23.7% +/- 1.4% vasodilation. With the cardioplegic solution containing a 40 mmol/L concentration of potassium, the initial responses to 5-hydroxytryptamine and papaverine were again similar (+21.5% +/- 2.5% and +24.1% +/- 3.0%, respectively). After cardioplegia, 5-hydroxytryptamine caused a significant vasoconstriction (-4.3% +/- 1.1%), whereas the response to papaverine was again maintained (+19.1% +/- 2.3%). The results of this study support the concept that hyperkalemic crystalloid cardioplegic solutions cause vascular damage possibly involving the endothelium or its function, which may adversely affect vascular responsiveness.
authors.affiliation: Cardiovascular Research, Rayne Institute, St. Thomas' Hospital, London, England.
authors.forename: C
authors.initials: C
authors.lastname: Saldanha
authors.forename: D J
authors.initials: DJ
authors.lastname: Hearse
mesh_terms: D000818:Animals; D002314:Cardioplegic Solutions / Q000494:pharmacology*; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000187:drug effects; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D010208:Papaverine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D017680:Potassium Compounds; D051381:Rats; D012701:Serotonin / Q000494:pharmacology*
chemical_list: D002314:Cardioplegic Solutions; D017680:Potassium Compounds; C018369:potassium cardioplegic solution; D009569:Nitric Oxide; D012701:Serotonin; D010208:Papaverine; D011188:Potassium