title: Role of potassium concentration in cardioplegic solutions in mediating endothelial damage.
abstract: We studied the effect of potassium concentration in cardioplegic solutions on endothelial function by examining its influence on 5-hydroxytryptamine- (5-HT) and nitroglycerin-induced vasodilation in the isolated rat heart. Forty-eight rat hearts were perfused on a modified Langendorff preparation. After a baseline record of increase in coronary flow induced by 10(-7) M 5-HT and 10 micrograms/mL nitroglycerin, the hearts were perfused for 30 or 60 minutes with either St. Thomas' solution or Bretschneider solution containing 20 mmol/L of potassium or for 30 minutes with either solution containing 30 mmol/L of potassium (n = 8 in each). Initially, 5-HT and nitroglycerin caused a 39.0% +/- 3.3% and 39.7% +/- 2.8% increase in coronary flow, respectively. After 30 or 60 minutes' perfusion with St. Thomas' solution containing 20 mmol/L of potassium, there was little change in the response to 5-HT or nitroglycerin (5-HT, 43.1% +/- 4.1%; nitroglycerin, 38% +/- 3.2%). Similarly, perfusion with Bretschneider solution (20 mmol/L K+) for 30 or 60 minutes did not alter the degree of vasodilation (5-HT, 39.2% +/- 2.9%; nitroglycerin, 38.0% +/- 3.3%). However, perfusion with St. Thomas' solution containing 30 mmol/L of potassium for 30 minutes abolished the endothelial-dependent 5-HT-induced vasodilation (5-HT, -1.6% +/- 1.4%; nitroglycerin, 36.9% +/- 2.2%). Perfusion with Bretschneider solution (30 mmol/L K+) gave similar results (5-HT, -2.1% +/- 1.2%; nitroglycerin, 36.4% +/- 1.7%). We conclude that the concentration of potassium in cardioplegic solutions plays a critical role in causing functional endothelial damage.
authors.affiliation: National Heart and Lung Institute, London, United Kingdom.
authors.forename: P S
authors.initials: PS
authors.lastname: Mankad
authors.forename: A H
authors.initials: AH
authors.lastname: Chester
authors.forename: M H
authors.initials: MH
authors.lastname: Yacoub
mesh_terms: D000818:Animals; D002314:Cardioplegic Solutions / Q000009:adverse effects*; D003326:Coronary Circulation / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D005996:Nitroglycerin / Q000494:pharmacology; D011188:Potassium / Q000009:adverse effects*; D051381:Rats; D012701:Serotonin / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects
chemical_list: D002314:Cardioplegic Solutions; D012701:Serotonin; D005996:Nitroglycerin; D011188:Potassium