title: Tolerance of epicardial coronary endothelium and smooth muscle to hyperkalemia.
abstract: Results of previous studies have suggested that high K+ concentrations in cardioplegic solutions may be detrimental to coronary endothelium in perfused hearts, as determined from changes in the coronary flow rate, but the direct functional changes in endothelium secondary to hyperkalemia have not been fully studied. To determine the effect of the K+ concentration in a physiologic solution (Krebs') and in St. Thomas' cardioplegic solution, and the effect of exposure time on endothelium and smooth muscle, porcine coronary artery rings were set up in organ baths under a physiologic pressure. The effect of exposure to Krebs' solution containing 5.9 or 50 mmol/L K+ or to St. Thomas' solution containing 16 or 50 mmol/L K+, for either 2 hours (group I) or 4 hours (group II), was examined. The solutions were continuously aerated with 95% oxygen and 5% carbon dioxide to exclude the effects of ischemia and hypoxia. The rings were then washed and contracted with K+ (25 mmol/L). The ability to release endothelium-derived relaxing factor (EDRF) in response to an EDRF stimulus (substance P) was used as an index of endothelial function. Smooth muscle function was evaluated in terms of the K(+)-induced contraction force and the relaxation induced with glyceryl trinitrate, in addition to the maximal substance P-induced relaxation. The maximal relaxation induced by substance P did not decrease by incubation with 50 mmol/L K+ in any group (p > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: G W
authors.initials: GW
authors.lastname: He
authors.forename: C Q
authors.initials: CQ
authors.lastname: Yang
authors.forename: G J
authors.initials: GJ
authors.lastname: Wilson
authors.forename: I M
authors.initials: IM
authors.lastname: Rebeyka
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000009:adverse effects; D002122:Calcium Chloride / Q000009:adverse effects; D002314:Cardioplegic Solutions / Q000009:adverse effects*; D003331:Coronary Vessels / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D007552:Isotonic Solutions / Q000009:adverse effects; D008274:Magnesium / Q000009:adverse effects; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism; D005996:Nitroglycerin / Q000494:pharmacology; D011188:Potassium / Q000008:administration & dosage / Q000009:adverse effects*; D011189:Potassium Chloride / Q000009:adverse effects; D012965:Sodium Chloride / Q000009:adverse effects; D013373:Substance P / Q000494:pharmacology; D013552:Swine
chemical_list: D001639:Bicarbonates; D002314:Cardioplegic Solutions; D007552:Isotonic Solutions; C051865:Krebs-Ringer solution; C041711:St. Thomas' Hospital cardioplegic solution; D009569:Nitric Oxide; D013373:Substance P; D012965:Sodium Chloride; D011189:Potassium Chloride; D005996:Nitroglycerin; D008274:Magnesium; D002122:Calcium Chloride; D011188:Potassium